Engineering › Aerospace Engineering

Aerodynamics and Fluid Dynamics Research

Works Count: 39844

Wikipedia

Description

This cluster of papers focuses on the aerodynamic characteristics, crosswind effects, turbulent wakes, and drag reduction techniques for high-speed trains and vehicles. It includes research on ground effect, flow structures, and feedback control to improve the performance and stability of trains in various wind conditions.

Keywords

Aerodynamics; High-Speed Trains; Crosswind; Turbulent Wake; Ground Effect; Wind Tunnel; Flow Structures; Drag Reduction; Vehicle Dynamics; Railway Bridges

Flow and Turbulence Structure in the Wake of a Simplified Car Model

2003-03-03

H. Lienhart , Stefan Becker

A comprehensive study using LDA (Laser Doppler Anemometry), HWA (Hot-Wire Anemometry) and static pressure measurements was performed in order to investigate the flow and turbulence structure around a simplified car … A comprehensive study using LDA (Laser Doppler Anemometry), HWA (Hot-Wire Anemometry) and static pressure measurements was performed in order to investigate the flow and turbulence structure around a simplified car model.The aim was to supply a detailed data set acquired under well defined boundary conditions to be used as reference data for numerical simulations in general and the validation and verification of refined turbulence models in particular. Because of the fact that the losses in the detached wake region make the major contribution to the aerodynamic drag and the prediction accuracy of the wake is a quite selective criteria for the turbulence models the study focused to the wake behind a simplified car model.

Some Salient Features Of The Time-Averaged Ground Vehicle Wake

1984-02-01

Shehzad Ahmed , G. Ramm , G. Faltin

For a basic ground vehicle type of bluff body, the time averaged wake structure is analysed. At a model length based reynolds number of 4.29 million, detailed pressure measurements, wake … For a basic ground vehicle type of bluff body, the time averaged wake structure is analysed. At a model length based reynolds number of 4.29 million, detailed pressure measurements, wake survey and force measurements were done in a wind tunnel. Some flow visualisation results were also obtained. Geometric parameter varied was base slant angle. A drag breakdown revealed that almost 85% of body drag is pressure drag. Most of this drag is generated at the rear end. Wake flow exhibits a triple deck system of horseshoe vortices. Strength, existence and merging of these vortices depend upon the base slant angle. Characteristic features of the wake flow for the low drag and high drag configurations is described. Relevance of these phenomena to real ground vehicle flow is addressed.

Multivariate interpolation for fluid-structure-interaction problems using radial basis functions

2001-02-01

Armin Beckert , Holger Wendland

High-Lift Aerodynamics

1975-06-01

A. M. O. Smith

Comprehensive Design of Axisymmetric Wind Tunnel Contractions

1975-06-01

Thomas Morel

Design charts for wind tunnel contractions are developed using an inviscid, incompressible flow analysis. A contour formed of two cubic arcs joined smoothly together was found to be a good … Design charts for wind tunnel contractions are developed using an inviscid, incompressible flow analysis. A contour formed of two cubic arcs joined smoothly together was found to be a good choice for a wall shape. Therefore, it was selected as the basis for a one-parameter family of wall shapes, which was then investigated in detail. The design chart parameters are the maximum wall pressure coefficients at the inlet (as an indicator of the danger of separation at the inlet end) and at the exit (which is related to the exit velocity nonuniformity). For any choice of these two parameters the charts yield the shape parameter and the nozzle length for this particular family of shapes. The charts may be used to design nozzles with no local separation at the inlet, and with any desired exit velocity uniformity. When the two pressure coefficients are chosen so that separation at both ends is just avoided, the exit boundary layer thickness should be near its minimum.

Laminar Flow and Convective Transport Processes

1993-01-01

L. Gary Leal

Computational study of flow around a simplified car body

2007-08-08

Emmanuel Guilmineau

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The Physiology and Medicine of Diving and Compressed Air Work.

1970-01-01

Peter B. Bennett , David H. Elliott

Vortex Shedding From a Circular Cylinder of Finite Length Placed on a Ground Plane

1992-12-01

Shiki Okamoto , Yukisada Sunabashiri

This paper describes a study of changes in the vortex formation and the turbulent wake from a circular cylinder with a finite aspect ratio, placed on a ground plane. The … This paper describes a study of changes in the vortex formation and the turbulent wake from a circular cylinder with a finite aspect ratio, placed on a ground plane. The experiment was carried out in an N.P.L. blow down type wind-tunnel, with a working section of 500 mm × 500 mm × 2,000 mm, and between the Reynolds number 2.5 × 104 and 4.7 × 104. The surface-pressure distributions on the circular cylinder were measured and the drag coefficient was determined from these measurements. Vortices of two kinds generated in the flow-field around the cylinder were observed. The power spectrum, auto-correlation, space-correlation, velocity defects, and turbulent intensities in the turbulent wake behind a circular cylinder were also measured. It was found that the flow pattern changed rapidly above aspect ratio H/D = 4, with vortex shedding changing from symmetric “arch” type to antisymmetric “Karman” type.

Introduction of a New Realistic Generic Car Model for Aerodynamic Investigations

2012-04-13

Angelina I. Heft , Thomas Indinger , Nikolaus A. Adams

Small Airway Dimensions in Smokers with Obstruction to Airflow

1990-09-01

Carol H. Bosken , B. R. Wiggs , Peter D. Paré +1 more

The obstruction to airflow that develops in some cigarette smokers is thought to be related to inflammation of small airways. However, the mechanism by which inflammation leads to obstruction has … The obstruction to airflow that develops in some cigarette smokers is thought to be related to inflammation of small airways. However, the mechanism by which inflammation leads to obstruction has not been elucidated. We performed morphometry to determine if the airways of patients with obstruction were thicker than normal. Sixty smokers were selected from those undergoing resectional lung surgery. They were grouped according to their FEV1/FVC ratio (FEV1% control = 77%, FEV1 obstructed = 55%) and matched for age, sex, and height. Wall area (mm2), perimeter (mm), and diameter (mm) were measured by a modification of the technique of James and coworkers (7). The relaxed luminal diameter (mm) and wall thickness (mm) were calculated from these values. A pathology score for inflammation and fibrosis was assigned to each patient, and the percentage of the wall made up of muscle, epithelium, and connective tissue was determined by point counting. Two hundred airways, 90% of which were membranous bronchioles, were measured in each group. The mean-measured luminal diameter in the controls was 0.81 mm and in the obstructed patients 0.70 mm (p ⩽ 0.05). The regression lines relating wall thickness to calculated luminal diameter showed that the airways of the obstructed patients were thicker throughout the size range measured (p ⩽ 0.005). The muscle, epithelium, and connective tissue were all increased in the obstructed patients (p ⩽ 0.001). In addition, the wall thickness correlated with the pathology score (r = 0.6074, p ⩽ 0.002). We conclude that part of the increased resistance to airflow that is found in smokers is related to narrowed small airways that have thickened walls.

Pressure probes for fluid measurement

1975-01-01

SH Chue

The flow around a surface-mounted cube in uniform and turbulent streams

1977-02-22

Ian P. Castro , Alan Robins

An experimental investigation of the flow around surface-mounted cubes in both uniform, irrotational and sheared, turbulent flows is described. The shear flow was a simulated atmospheric boundary layer with a … An experimental investigation of the flow around surface-mounted cubes in both uniform, irrotational and sheared, turbulent flows is described. The shear flow was a simulated atmospheric boundary layer with a height ten times the body dimension. Measurements of body surface pressures and mean and fluctuating velocities within the wake are presented. In the latter case a pulsed-wire anemometer was used extensively since the turbulent intensities were much too high for effective use of more standard instrumentation. The clear effects of upstream turbulence and shear on the wake flow are described, comparisons with the somewhat sparse measurements of previous workers are made and the relevance of recent theoretical attempts to describe the flow, as opposed to numerical calculation techniques to predict it, is briefly discussed.

Closure Profiles in Cooling Systems

1986-01-01

M. H. DODSON

Flow Around a Simplified Car, Part 1: Large Eddy Simulation

2005-05-12

Siniša Krajnović , Lars Davidson

Large eddy simulations (LES) were made of flows around a generic ground vehicle with sharp edges at the rear end (an Ahmed body with a 25° angle of the rear … Large eddy simulations (LES) were made of flows around a generic ground vehicle with sharp edges at the rear end (an Ahmed body with a 25° angle of the rear slanted surface). Separation of the flow at the rear results in large regions with recirculating flow. As the separation is determined by the geometry, the Reynolds number effects are minimized. Resolution requirements of this recirculating flow are smaller than those in LES of wall attached flows. These two consequences of the geometry of the body are used to predict the experimental flow at relatively high Reynolds number. Recommendations are presented for the preparation and realization of LES for vehicle flows. Comparison of the LES results with the experimental data shows good agreement.

Development of DDES and IDDES Formulations for the k-ω Shear Stress Transport Model

2011-11-21

M. S. Gritskevich , A V Garbaruk , Jochen Schütze +1 more

Wing-in-ground effect vehicles

2006-05-01

Kirill V. Rozhdestvensky

Internal combustion engine cold-start efficiency: A review of the problem, causes and potential solutions

2014-04-03

Andrew Roberts , Richard Brooks , P.H. Shipway

Legislation on vehicle emissions continues to become more stringent in an effort to minimise the impact of internal combustion engines on the environment. One area of significant concern in this … Legislation on vehicle emissions continues to become more stringent in an effort to minimise the impact of internal combustion engines on the environment. One area of significant concern in this respect is that of the cold-start; the thermal efficiency of the internal combustion engine is significantly lower at cold-start than when the vehicle reaches steady state temperatures owing to sub-optimal lubricant and component temperatures. The drive for thermal efficiency (of both the internal combustion engine and of the vehicle as a whole) has led to a variety of solutions being trialled to assess their merits and effects on other vehicle systems during this warm-up phase (and implemented where appropriate). The approaches have a common theme of attempting to reduce energy losses so that systems and components reach their intended operating temperature range as soon as possible after engine start. In the case of the engine, this is primarily focused on the lubricant system. Lubricant viscosity is highly sensitive to temperature and the increased viscosity at low temperatures results in higher frictional and pumping losses than would be observed at the target operating temperature. The approaches used to tackle the problem include the use of phase change materials (to reduce the cool-down rate during a period following engine running) [1], [2] and the use of thermal barrier coatings in an attempt to insulate the cylinder bore and prevent heat loss (thus increasing the amount of energy utilised as brake work [3]). A range of system alterations have also been trialled including diversion systems on the lubricant circuit to reduce thermal losses. Presented here is a critical review of the research into vehicle thermal management during the cold-start phase which has been driven by a desire to improve both engine and overall vehicle engine efficiency. The review includes both system developments and material selection issues and the role the two fields have to play in tackling this critical issue.

Measurements of the cross wind forces on trains

2004-04-26

Chris Baker , John E. Jones , F. Lopez-Calleja +1 more

The flow around high speed trains

2009-12-24

Chris Baker

Crosswind action on rail vehicles: Wind tunnel experimental analyses

2008-04-09

M. Bocciolone , Federico Cheli , Roberto Corradi +2 more

Atmospheric Winds and Their Implications for Microair Vehicles

2006-11-01

Simon Watkins , Juliette Milbank , Benjamin Loxton +1 more

Major challenges to low speed microllight are the transient and time-averaged velocities arising from the atmospheric boundary layer, particularly turbulence a few meters above the ground. In this paper, prior … Major challenges to low speed microllight are the transient and time-averaged velocities arising from the atmospheric boundary layer, particularly turbulence a few meters above the ground. In this paper, prior work on the temporal and spatial characteristics of the atmospheric boundary layer, close to the ground, and the relative turbulence as perceived by a moving craft, are considered. New measurements are described that document the time-, averaged and transient velocities at a height of 4 in above the ground. These were made using a bank of four multihole pressure probes laterally separated by 150 and 50 mm on a mast above a test car. Transient How pitch angles were investigated and it was found that the overall variation with lateral separation decreased relatively slowly with reducing separation, but that both this and the pitch angle coherence may be described nondimensionally. As the slow decrease in pitch variation with lateral spacing implies that the roll inputs arising from vertical fluctuations would increase with reducing span, it is speculated that increasingly active and authoritative control systems are required.

A<scp>ERODYNAMICS OF</scp> H<scp>IGH</scp>-S<scp>PEED</scp> T<scp>RAINS</scp>

2001-01-01

Joseph A. Schetz

▪ Abstract This review highlights the differences between the aerodynamics of high-speed trains and other types of transportation vehicles. The emphasis is on modern, high-speed trains, including magnetic levitation (Maglev) … ▪ Abstract This review highlights the differences between the aerodynamics of high-speed trains and other types of transportation vehicles. The emphasis is on modern, high-speed trains, including magnetic levitation (Maglev) trains. Some of the key differences are derived from the fact that trains operate near the ground or a track, have much greater length-to-diameter ratios than other vehicles, pass close to each other and to trackside structures, are more subject to crosswinds, and operate in tunnels with entry and exit events. The coverage includes experimental techniques and results and analytical and numerical methods, concentrating on the most recent information available.

An experimental flow with zero skin friction throughout its region of pressure rise

1959-01-01

B. S. Stratford

A flow has been produced having effectively zero skin friction throughout its region of pressure rise, which extended for a distance of 3 ft. No fundamental difficulty was encountered in … A flow has been produced having effectively zero skin friction throughout its region of pressure rise, which extended for a distance of 3 ft. No fundamental difficulty was encountered in establishing the flow and it had, moreover, a good margin of stability. The dynamic head in the zero skin friction boundary layer was found to be linear at the wall (i.e. u ∞ y½), as predicted theoretically in the previous paper (Stratford 1959).The flow appears to achieve any specified pressure rise in the shortest possible distance and with probably the least possible dissipation of energy for a given initial boundary layer. Thus an aerofoil which could utilize it immediately after transition from laminar flow would be expected to have a very low drag. A design pressure distribution (besides having the usual safety margin against stall) should have a slightly more gradual start to the pressure rise than in the present experiment, as small errors close to the discontinuity can cause difficulty.

A robust upwind discretization method for advection, diffusion and source terms

1993-01-01

Barry Koren

Aerodynamics of high-speed railway train

2002-08-01

R.S. Raghunathan , H.-D Kim , Toshiaki Setoguchi

Turbulence modeling for high speed flows

1992-01-06

T. J. Coakley , P. G. Huang

An investigation of turbulence models for high speed flows is presented. The flows consist of simple 2D flows over flat plates and complex shock-wave boundary-layer interaction flows over ramps and … An investigation of turbulence models for high speed flows is presented. The flows consist of simple 2D flows over flat plates and complex shock-wave boundary-layer interaction flows over ramps and wedges. The flows are typical of those encountered by high speed vehicles such as the NASP. The turbulence models investigated include various two-equation models which, as a class, are considered to be well suited to the design of high speed vehicles. A description and discussion of the specific models is given and includes both baseline or uncorrected models, and model corrections which are needed to improve predictions of complex flows. It is found that most of the models studied are able to give good predictions of the flat plate flows, and some of the models are able to predict some of the complex flows, but none of them are able to accurately predict all of the complex flows. Recommendations for future model improvements are discussed.

Panel Methods in Computational Fluid Dynamics

1990-01-01

John L. Hess

in the field of computational fluid dynamics that the more generally the physics of the flow is modeled by a method, the less general is the boundary geometry to which … in the field of computational fluid dynamics that the more generally the physics of the flow is modeled by a method, the less general is the boundary geometry to which the method is applicable. Part of the difficulty lies in the stringent requirements on the calculational grid in the field of flow. According to the above observation, the simp lest meaningful flow physics- that of invi scid, in compressible potential flow should be applicable to the most general geometries. Indeed, as is well known, this problem can be formulated as a linear integral equation over the boundary, thus eliminating the need for a field grid and allowi ng the possibility that a potential-flow method formulated in this way can be capable 'of obtaining flow solutions about completely arbitrary con figurations. Happily, this generality substantially can be achieved in prac tice, although with more analytical and programming effort than most publications on the subject are prepared to admit. At the same time, the predictions of such methods have been found to agree well with experiment over a surprisingly large range of flow conditions. Even when their results fail to give the proper experi mental values, they are frequently useful in predicting the incremental effect of a proposed design change or in ordering various designs in terms of effectiveness. This perhaps fortuitous agreement with real flow, combined with their geometric generality, has made numeri cal potential-flow methods indispensable design tools in many fields. For example, in the author's company a major design calculation (e.g. flow

Aerodynamics of a Single Element Wing in Ground Effect

2000-11-01

Jonathan Zerihan , Xin Zhang

A study was performed of a cambered, double-element, high-lift wing operating in ground effect. The effect of ground proximity and flap setting has been quantified in terms of aerodynamic performance … A study was performed of a cambered, double-element, high-lift wing operating in ground effect. The effect of ground proximity and flap setting has been quantified in terms of aerodynamic performance and off-surface flowfield characteristics. Measurements include surface pressure taps, force, surface streaklines, and laser doppier anemometry (LDA). It was found from the Haw visualization that the flow is three-dimensional (3D) towards the wing tip with the main element generating most of the downforce, but retains quasi-2D features near the centre of the wing. However, at large heights the downforce increases asymptotically with a reduction in height, Then there is either a plateau, in the case of a low flap angle, or a reduction in down-force, in the case of a large flap angle. The downforce then increases again until it reaches a maximum, and then reduces at a height near the ground. The maximum downforce is dictated by gains in downforce from lower surface suction increases and losses in downforce due to upper surface pressure losses and lower surface suction losses, with a reduction in height. For the high flap angle, there is a sharp reduction just beyond the maximum, due to the boundary layer separating, and a resultant loss of circulation on. the main element.

Framework of vehicle–bridge–wind dynamic analysis

2004-04-26

C.S. Cai , Suren Chen

Aerodynamics of Road Vehicles

1987-01-01

AERODYNAMICS OF RACE CARS

2005-12-17

Joseph Katz

Race car performance depends on elements such as the engine, tires, suspension, road, aerodynamics, and of course the driver. In recent years, however, vehicle aerodynamics gained increased attention, mainly due … Race car performance depends on elements such as the engine, tires, suspension, road, aerodynamics, and of course the driver. In recent years, however, vehicle aerodynamics gained increased attention, mainly due to the utilization of the negative lift (downforce) principle, yielding several important performance improvements. This review briefly explains the significance of the aerodynamic downforce and how it improves race car performance. After this short introduction various methods to generate downforce such as inverted wings, diffusers, and vortex generators are discussed. Due to the complex geometry of these vehicles, the aerodynamic interaction between the various body components is significant, resulting in vortex flows and lifting surface shapes unlike traditional airplane wings. Typical design tools such as wind tunnel testing, computational fluid dynamics, and track testing, and their relevance to race car development, are discussed as well. In spite of the tremendous progress of these design tools (due to better instrumentation, communication, and computational power), the fluid dynamic phenomenon is still highly nonlinear, and predicting the effect of a particular modification is not always trouble free. Several examples covering a wide range of vehicle shapes (e.g., from stock cars to open-wheel race cars) are presented to demonstrate this nonlinear nature of the flow field.

Adaptation of Eddy-Viscosity Turbulence Models to Unsteady Separated Flow Behind Vehicles

2004-01-01

Florian Menter , M. Kuntz

Low Reynolds Number Aerodynamics

1989-01-01

Review of research on high-speed railway aerodynamics in China

2019-07-01

Hong-qi Tian

Abstract High-speed railway aerodynamics is the key basic science for solving the bottleneck problem of high-speed railway development. This paper systematically summarizes the aerodynamic research relating to China’s high-speed railway … Abstract High-speed railway aerodynamics is the key basic science for solving the bottleneck problem of high-speed railway development. This paper systematically summarizes the aerodynamic research relating to China’s high-speed railway network. Seven key research advances are comprehensively discussed, including train aerodynamic drag-reduction technology, train aerodynamic noise-reduction technology, train ventilation technology, train crossing aerodynamics, train/tunnel aerodynamics, train/climate environment aerodynamics, and train/human body aerodynamics. Seven types of railway aerodynamic test platform built by Central South University are introduced. Five major systems for a high-speed railway network—the aerodynamics theoretical system, the aerodynamic shape (train, tunnel, and so on) design system, the aerodynamics evaluation system, the 3D protection system for operational safety of the high-speed railway network, and the high-speed railway aerodynamic test/computation/analysis platform system—are also introduced. Finally, eight future development directions for the field of railway aerodynamics are proposed. For over 30 years, railway aerodynamics has been an important supporting element in the development of China’s high-speed railway network, which has also promoted the development of high-speed railway aerodynamics throughout the world.

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Calculation of Nonlifting Potential Flow About Arbitrary Three-Dimensional Bodies

1964-09-01

John L. Hess , A. M. O. Smith

A general method is described for calculating, with the aid of an electronic computer, the incompressible potential flow about arbitrary, nonlifting, three-dimensional bodies. The method utilizes a source density distribution … A general method is described for calculating, with the aid of an electronic computer, the incompressible potential flow about arbitrary, nonlifting, three-dimensional bodies. The method utilizes a source density distribution on the surface of the body and solves for the distribution necessary to make the normal component of fluid velocity zero on the boundary. Plane quadrilateral surface elements are used to approximate the body surface, and the integral equation for the source density is replaced by a set of linear algebraic equations for the values of the source density on the quadrilateral elements. When this set of equations has been solved, the flow velocity both on and off the body surface is calculated. After the basic ideas and equations have been derived end discussed, the accuracy of the method is exhibited by means of comparisons with analytic solutions, and its usefulness is shown by comparing calculated pressure distributions with experimental data. Some of the design problems to which the method has been applied are also presented, to indicate the variety of flow situations that can be calculated by this approach.

Aerodynamics of Wind Turbines

2015-06-10

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Supersonic base flow experiments in the near-wake of a cylindrical afterbody

1993-07-06

J. L. Herrin , J. C. Dutton

98/03125 Fitting wind speed distributions: a case study

1998-07-01

Wind Tunnel Aerodynamic Tests of Six Airfoils for Use on Small Wind Turbines

2004-01-05

Michael S. Selig , Bryan D. McGranahan

Aerodynamics of Road Vehicles

1993-01-01

W Hucho , G Sovran

Aerodynamics of a Lifting System in Extreme Ground Effect

2000-01-01

Kirill V. Rozhdestvensky

Computational Analysis of Wind-Induced Driving Safety Under Wind–Rain Coupling Effect Based on Field Measurements

2025-06-24

Dandan Xia , Chen Chen , Yanan Hu +3 more | Vehicles

Extreme events such as tropical cyclones frequently occur in coastal areas in China. With high wind speeds and rainfall during such extreme events, the vehicles on sea-crossing bridges may face … Extreme events such as tropical cyclones frequently occur in coastal areas in China. With high wind speeds and rainfall during such extreme events, the vehicles on sea-crossing bridges may face severe instability problems. In this study, the dynamics of vehicles on a cross-sea bridge under the wind–rain coupling effect were analyzed based on field measurement data using computational fluid dynamics (CFD). Wind field parameters of the coastal area in China were obtained using wind speed data from measurement towers. Based on CFD, the sliding grid method was applied to establish an aerodynamic analysis model of a container truck moving on a bridge under wind and rain conditions. The discrete phase model based on the Euler–Lagrange method was used to investigate the influence of rain and obtain the aerodynamic characteristics of the truck under the coupled wind and rain effects. Based on the computational analysis results, considering the turbulence intensity, the yaw angle peaks of the tractor and trailer increased by 5.2% and 3.8%, respectively, and the lateral displacement of the truck’s center of mass increased by 9.8%. Rainfall may cause the vehicle to have a higher response, resulting in a high risk of skidding. The results show that skidding occurs for the considered container truck when rainfall is at 9.8%. These results can provide parameters for traffic control strategies under such extreme climate events in coastal areas.

Gap effects on the aerodynamic characteristics and flow patterns of a long-span rail-cum-road bridge girder with three separated boxes

2025-06-24

Yize Ran , Wen‐Li Chen , Hui Li +1 more | Journal of Wind Engineering and Industrial Aerodynamics

Investigation of Driving Safety on Desert Highways Under Crosswind Direction Disturbances

2025-06-23

Z.M. Zhang , Songli Chen , Wei Zhang | Vehicles

Desert highways, with open terrain and minimal wind barriers, expose high-speed vehicles to significant stability risks from combined crosswinds and sand accumulation. This study uses numerical simulation to assess the … Desert highways, with open terrain and minimal wind barriers, expose high-speed vehicles to significant stability risks from combined crosswinds and sand accumulation. This study uses numerical simulation to assess the effects of varying wind direction angles and sand thicknesses on vehicle stability across different models. Five dynamic indicators—lateral displacement, yaw angle, aerodynamic sideslip angle, lateral acceleration, and roll angle—are analyzed. The results show that a 120° wind angle causes the most pronounced parameter changes, while stability is lowest at 150°, where critical thresholds are reached within 0.75 s and danger thresholds by 2.25 s. Rapid wind speed variations further degrade stability. Compared to small SUVs, mid-size SUVs perform worse under identical conditions. A comprehensive stability evaluation function is proposed to quantify the combined impact of wind angle and surface friction, providing a new approach for safety assessment on sand-covered desert roads.

Experimental investigation of a high Reynolds number turbulent wake generated by a vehicle-like bluff body

2025-06-23

NULL AUTHOR_ID | Physical Review Fluids

Vortex ring induced by a disk translating toward or away from a wall

2025-06-20

NULL AUTHOR_ID | Physical Review Fluids

Video-Analysis and Knowledge on Rewind

2025-06-18

Ajit Singh , Christian Meier zu Verl , René Tuma | Routledge eBooks

Video analysis and knowledge on rewind

2025-06-18

Ajit Singh , René Tuma , Christian Meier zu Verl | Routledge eBooks

Fluid-Structure-Interaction in Butterfly Valves for Hydropower: A Numerical and Experimental Study

2025-06-18

Manuel Berger , Lukas Zingerle , Christian Mayerl +2 more | Results in Engineering

High precision Numerical Simulation of Passenger Cars Based on Numerical Wind Tunnel

2025-06-17

Yan Ma , Ying Li , Jing Zhao +7 more | Research Square (Research Square)

<title>Abstract</title> This study investigates the high-precision numerical simulation technology of passenger cars based on a numerical wind tunnel, develops a virtual numerical wind tunnel model based on the existing vehicle … <title>Abstract</title> This study investigates the high-precision numerical simulation technology of passenger cars based on a numerical wind tunnel, develops a virtual numerical wind tunnel model based on the existing vehicle wind tunnel in China, and simulates the flow field characteristics in the actual wind tunnel by choosing the appropriate mesh strategy and boundary conditions. The realizable k-ɛ, shear stress transport (SST) k-ω, and SST detached eddy simulation turbulence models are used to simulate numerically the aerodynamic drag and lift of the real vehicle. These simulated values are compared with the actual wind tunnel test values. Results show that the numerical wind tunnel can successfully simulate the flow field characteristics in the wind tunnel, such as turbulence degree, airflow deflection angle, pressure gradient, and boundary layer displacement thickness. Moreover, the simulation accuracy of the numerical wind tunnel is higher than that of the traditional rectangular open-domain simulation. This study confirms the capability of the numerical wind tunnel in simulating the flow field characteristics in wind tunnels, thereby improving the numerical simulation accuracy and providing a new perspective for the numerical simulation study of automotive aerodynamics.

Numerical investigation of aerodynamic features and flow structure of a high-speed high-temperature superconducting maglev train under crosswind based on reduced-order methods

2025-06-17

Zongpeng Li , Xiaofei Wang , Tian‐Hao Ma +4 more | Journal of Fluids and Structures

Investigation of the Effect of Stagnation Surface and Diffuser Angle on Aerodynamic Performance: A Case Study on Locally Built Isuzu Bus

2025-06-17

Gebremeskel Kahsay Atsbha , Dinku Seyoum Zeleke , Mezid Abdella Hamza +1 more | Research Square (Research Square)

<title>Abstract</title> The ISUZU midi bus is the primary mode of transportation for the majority of Ethiopians. Due to its blunt, rectangular appearance and high drag resistance forces, the bus has … <title>Abstract</title> The ISUZU midi bus is the primary mode of transportation for the majority of Ethiopians. Due to its blunt, rectangular appearance and high drag resistance forces, the bus has poor aerodynamic shapes and uses more fuel. Therefore, the study objective is to reduce the total aerodynamic drag force, which in turn reduces power demand, fuel consumption, and carbon dioxide emissions. As a result, the diffuser angle and bus stagnation surface shape are aerodynamically optimized. Solid Work CAD 2023 is utilized in the development of the model. Eight different car models were developed and analyzed. CFD and ANSYS Fluent 19.2 were used for the analyses. With a 15º diffuser angle in the rear weak zone and a taper in front and an arc segment on both sides in the stagnation surface, the model-6 had the lowest Cd and Fd values, measuring 0.2915 and 225.32N at 70 km/h and 0.3111 and 594.22N at 110 km/h, respectively. At 70 km/h and 110 km/h, respectively, the Cd reduction percentages attained with this model were 51.21% (48.8% due to the frontal effect and 2.41% due to the diffuser angle impact) and 50.79% (48.81% due to the frontal effect and 1.98% because of the diffuser angle impact). Compared to the baseline bus, the coefficient of drag was, on average, 51% lower. In comparison to the baseline model, model six uses 5026.6 W less power at 70 km/h and 18332.03 W less power at 110 km/h. Compared to the baseline model, the modified model six uses 1.45 L/h less gasoline at 70 km/h and 5.28 L/h less fuel at 110 km/h. At 70 km/h and 110 km/h, model six's CO2 decrease is 12.17 tons per year and 44.31 tons per year, respectively, compared to the baseline model.

Thermal Management of Traction Motors in Electrified Vehicles: A Critical Review on Cooling Technologies and Future Directions

2025-06-17

Xinyang Chen | Science and Technology of Engineering Chemistry and Environmental Protection

As sustainable transportation solutions, New Energy Vehicles (NEVs) have gained global prominence amidst escalating energy crises and environmental challenges. The operational stability and energy efficiency of traction motors—critical to NEV … As sustainable transportation solutions, New Energy Vehicles (NEVs) have gained global prominence amidst escalating energy crises and environmental challenges. The operational stability and energy efficiency of traction motors—critical to NEV powertrain performance—are fundamentally dependent on advanced thermal management systems. This paper systematically reviews motor cooling technologies, including air cooling, liquid cooling, and evaporative cooling. Through patent analyses and case studies such as the Audi e-tron GT’s dual-loop liquid cooling system, the study identifies emerging trends in hybrid cooling integration and intelligent thermal regulation. The review concludes that next-generation cooling systems must balance efficiency, reliability, and lightweight design to enhance motor longevity and reduce energy consumption while addressing evolving performance demands in NEV applications [4].

On enhancing anti-overturning performance of a high-speed train with side airfoils in crosswinds

2025-06-16

Juannong Chen , Ao Xu , Tanghong Liu +2 more | Journal of Wind Engineering and Industrial Aerodynamics

Numerical simulation of filter plate influence on flow field uniformity in dust collectors

2025-06-16

Jiayi Li , Shihang Li , Muze Han +6 more | Separation and Purification Technology

Wind Tunnel Investigation of Aeroelasticity on an Elastic Wing Coupled with Propeller Effects

2025-06-16

Changchuan Xie , Yali Shao , Zhitao Zhang +3 more | Advances in transdisciplinary engineering

This paper investigates the aeroelasticity of an elastic wing coupled with propeller effects as compared to rigid counterparts by conducting a wind tunnel experiment specifically tailored for the propeller/wing system, … This paper investigates the aeroelasticity of an elastic wing coupled with propeller effects as compared to rigid counterparts by conducting a wind tunnel experiment specifically tailored for the propeller/wing system, examining the variation in wing deformation and lift contribution rates due to the propeller effects. The empirical data derived from the experiment underscore the necessity of accounting for the characteristics of aeroelasticity in an elastic wing coupled with propeller effects, offering valuable engineering insights for the design and computational simulation of propeller-equipped aircraft.

Examining the Influence of Vehicle Speed on Thermal Comfort and Temperature Control in Vehicle Cabins

2025-06-15

Nurhayati Baharudin , Bukhari Manshoor , Muhammad Mohamed Salleh +3 more | Journal of Advanced Research in Fluid Mechanics and Thermal Sciences

The growing demand for improved vehicle efficiency and rapid cabin temperature regulation, specifically in hot-soaked vehicles, highlights the need to reduce occupant stress and discomfort. This study investigates the relationship … The growing demand for improved vehicle efficiency and rapid cabin temperature regulation, specifically in hot-soaked vehicles, highlights the need to reduce occupant stress and discomfort. This study investigates the relationship between vehicle speed and cabin temperature variation under urban driving conditions, focusing on speeds ranging from 40 to 100 kph. An experimental approach was employed, using thermocouples connected to a data logger to monitor and record temperature across five distinct cabin areas. The results reveal a significant correlation between increased vehicle speed and enhanced cabin cooling efficiency, with a 15 % reduction in average cabin temperature at speeds above 80 kph compared to lower speeds. Additionally, higher speeds resulted in a 20 % decrease in temperature variation across seating areas, indicating more stable and uniform cabin conditions. These findings underscore the potential of optimizing vehicle speed to improve thermal comfort and HVAC efficiency, particularly during urban driving scenarios.

Wind speed prediction for trains on bridges using enhanced variational mode decomposition assisted feature extraction and physical auxiliary mechanism

2025-06-15

Zhengfei Zhu , Yuan Jiang , Haicui Wang +1 more | Advances in Bridge Engineering

Abstract The operation safety and stability of trains is closely related with the wind speed. However, given the intricate nature of its characteristics, which encompass linearity, nonlinearity, nonstationarity etc., accurately … Abstract The operation safety and stability of trains is closely related with the wind speed. However, given the intricate nature of its characteristics, which encompass linearity, nonlinearity, nonstationarity etc., accurately predicting the short-term wind speed presents a notable obstacle. To this end, this paper presents a novel forecasting approach using the hybrid of enhanced variational mode decomposition (EVMD), auto-regressive integrated moving average (ARIMA), fully convolutional neural network (FCN), and physical auxiliary mechanism (PAM). This method not only can provide the accurately deterministic prediction, but also can produce the desired probabilistic prediction. Specifically, EVMD is developed based the mode aliasing problem for performing the data decomposition and reconstruction. Then, the combination of ARIMA and FCN is used to perform linear and nonlinear predictions. Finally, PAM is introduced into the above established model for realizing the desired deterministic and probabilistic predictions where the relationship among the wind speed data recorded at various time intervals and the data variability are considered. Numerical examples, utilizing two sets of measured wind speed data, underscore the efficacy and advantage of the developed method. For example, the proposed method can realize the reduction of the average of mean absolute error from 1.08 to 0.73 in comparison with ARIMA-FCN-PAM. Hence, the proposed method stands as a viable and efficient alternative for forecasting the short-term wind speed.

Optimization of Vertical Axis Wind Turbine Systems to Capture Vehicle-Induced Highway Winds

2025-06-14

Aydin Ulus , Stefan Ilie Moldovan | Energies

This study introduces an innovative set of guide vanes that increase the efficiency of Vertical Axis Wind Turbines (VAWT) using winds generated by vehicles traveling on highways. The increase in … This study introduces an innovative set of guide vanes that increase the efficiency of Vertical Axis Wind Turbines (VAWT) using winds generated by vehicles traveling on highways. The increase in efficiency is based on enhancing the airflow interaction as the vehicle moves past the turbine. Initial Computational Fluid Dynamics (CFD) simulations with two guide vanes setups demonstrated a 56.81% increase in power output under wind generated by passenger vehicles. Further design enhancements, incorporating three guide vanes with optimized geometries, led to a 242% improvement in power generation. Additional simulations evaluated the performance under wind conditions generated by larger vehicles, such as buses. The three guide vanes configuration yielded a 102% increase in energy capture efficiency in these scenarios. The findings suggest that vehicle-induced winds—typically an untapped energy source—can be effectively harvested using tailored turbine system designs. By integrating passive flow control strategies such as guide vanes, VAWTs can operate more efficiently in highway environments. This research highlights a novel pathway for enhancing renewable energy systems and supports broader efforts toward sustainable energy development through the utilization of unconventional wind sources. This performance enhancement is primarily due to the aerodynamic redirection of airflow toward the advancing blade and away from the returning blade, reducing drag and improving torque generation.

A Novel Curve-and-Surface Fitting-Based Extrapolation Method for Sub-Idle Component Characteristics of Aeroengines

2025-06-14

Yanyan Cui , Tianhong Zhang , Zhaohui Cen +2 more | Aerospace

The component characteristics of an aeroengine below idle speed are fundamental for start-up process simulations. However, due to experimental limitations, these characteristics must be extrapolated from data above idle speed. … The component characteristics of an aeroengine below idle speed are fundamental for start-up process simulations. However, due to experimental limitations, these characteristics must be extrapolated from data above idle speed. Existing extrapolation methods often suffer from insufficient utilization of available data, reliance on specific prior conditions, and an inability to capture unique operating modes (e.g., the stirring mode and turbine mode of compressor). To address these limitations, this study proposes a novel curve-and-surface fitting-based extrapolation method. The key innovations include: (1) extrapolating sub-idle characteristics through constrained curve/surface fitting of limited above-idle data, preserving their continuous and smooth nature; (2) transforming discontinuous isentropic efficiency into a continuous specific enthalpy change coefficient (SECC), ensuring physically meaningful extrapolation across all operating modes; (3) applying constraints during fitting to guarantee reasonable and smooth extrapolation results. Validation on a micro-turbojet engine demonstrates that the proposed method requires only conventional performance parameters (corrected flow, pressure/expansion ratio, and isentropic efficiency) above idle speed, yet successfully supports ground-starting simulations under varying inlet conditions. The results confirm that the proposed method not only overcomes the limitations of existing approaches but also demonstrates broader applicability in practical aeroengine simulations.

Numerical Study on the Influence of Cooling-Fin Geometry on the Aero-Thermal Behavior of a Rotating Tire

2025-06-14

Kintak Raymond Yu , SangWook Lee | Energies

An excessive temperature rise in vehicle tires during driving can degrade dynamic performance, safety, and fuel efficiency by increasing rolling resistance and softening materials. To mitigate these issues, it is … An excessive temperature rise in vehicle tires during driving can degrade dynamic performance, safety, and fuel efficiency by increasing rolling resistance and softening materials. To mitigate these issues, it is essential to enhance the cooling performance of tires without inducing significant aerodynamic penalties. In this study, we propose the use of sidewall-mounted cooling fins and investigate their aero-thermal effects under both ground-contact and no-ground-contact conditions. Seven fin configurations were tested, with installation angles ranging from −67.5° to 67.5°, with positive angles indicating an orientation opposite to the direction of wheel rotation and negative angles indicating alignment with the direction of rotation. High-fidelity unsteady Reynolds-averaged Navier–Stokes simulations were conducted using the SST k-w turbulence model. The sliding mesh technique was employed to capture the transient flow behavior induced by tire rotation. The results showed that, under no-ground-contact conditions, the 45° configuration achieved a 16.8% increase in convective heat transfer with an increase in drag less than 3%. Under ground-contact conditions, the 22.5° configuration increased heat transfer by over 13% with a minimal aerodynamic penalty (~1.7%). These findings provide valuable guidance for designing passive cooling solutions that improve tire heat dissipation performance without compromising aerodynamic efficiency.

Comment on ‘Variable viscosity effects on the flow of MHD hybrid nanofluid containing dust particles over a needle with Hall current–a Xue model exploration’

2025-06-13

Asterios Pantokratoras | Communications in Theoretical Physics

Abstract Many serious errors exist in the mentioned Ramzan and Alotaibi (2022, Commun. Theor. Phys. 74 05580) paper [1]. Abstract Many serious errors exist in the mentioned Ramzan and Alotaibi (2022, Commun. Theor. Phys. 74 05580) paper [1].

Aerodynamic and Impact Analysis of SAE BAJA Vehicle

2025-06-12

N. Trinadh Raju | INTERANTIONAL JOURNAL OF SCIENTIFIC RESEARCH IN ENGINEERING AND MANAGEMENT

Abstract This study presents a detailed aerodynamic and impact analysis of an SAE BAJA All- Terrain Vehicle (ATV) using SolidWorks and ANSYS simulation tools. The aerodynamic study aims to optimize … Abstract This study presents a detailed aerodynamic and impact analysis of an SAE BAJA All- Terrain Vehicle (ATV) using SolidWorks and ANSYS simulation tools. The aerodynamic study aims to optimize airflow around the vehicle to reduce drag, enhance fuel efficiency, and improve performance. Computational Fluid Dynamics (CFD) simulations reveal a drag force of approximately 185 N at 60 km/h and identify critical areas contributing to air resistance. The impact analysis evaluates the structural integrity of the roll cage and bumper through Finite Element Analysis (FEA), confirming crashworthiness against frontal and side impacts. Simulation results indicate Von Mises stresses within safe material limits and validate the vehicle's compliance with SAE safety standards. Recommendations include bumper reinforcement and aerodynamic refinements. The integrated computational approach ensures improved performance and driver safety.

Computational Fluid Dynamics Analysis of Aerodynamic Characteristics on Overtaking Vehicles in Crosswind Conditions

2025-06-12

Mohd Yunos Mohd Amirul Syafiq , Izuan Amin Ishak , Mohammad Arafat +4 more | International Journal of Automotive and Mechanical Engineering

Drivers frequently adjust their path due to crosswinds and overtaking, where adjacent vehicles significantly alter airflow. This study uses computational fluid dynamics to analyze the aerodynamic impact of overtaking maneuvers … Drivers frequently adjust their path due to crosswinds and overtaking, where adjacent vehicles significantly alter airflow. This study uses computational fluid dynamics to analyze the aerodynamic impact of overtaking maneuvers on simplified car models (Ahmed Bodies) under crosswind conditions. The investigation focuses on how drag, lift, and side force coefficients change during different overtaking stages at varying crosswind angles (0°, 15°, 30°, and 45°). The study focused on 2 Ahmed Body models, which are overtaking vehicle(A) and overtaking vehicle(B), in 5 different cases: before overtake, initiation of overtake, mid-overtake, completion of overtake, and after overtake. Results show that at a 15° crosswind, Car A has a higher drag coefficient (Cd: 0.3916), reducing performance and stability. At 30°, Car A shows a high lift coefficient (Cl: 0.9881); at 45°, Car B experiences a significant increase in side force coefficient (Cs: 3.1192). This is due to the pressure contour at the front corner of the vehicle surface and the vortex formation on the leeward side of the vehicles as yaw angles rise. Results show that crosswinds significantly increase aerodynamic forces and alter flow structures around vehicles. Specifically, the relative position of vehicles during overtaking greatly influences these forces, affecting vehicle stability.

A study on Wind-Wind energy for Electric Vehicles Charging Station on the Southern Highway of Thailand

2025-06-04

Napass Kangwantrakool , Kittinan Maliwan , Juntakan Taweekun | Journal of Advanced Research Design

This comprehensive research delves into the energy landscape of Southern Thailand. Leveraging sophisticated tools such as WAsP, the study conducts an exhaustive examination of the wind energy potential, taking into … This comprehensive research delves into the energy landscape of Southern Thailand. Leveraging sophisticated tools such as WAsP, the study conducts an exhaustive examination of the wind energy potential, taking into account the intricate geographical and climatic conditions of the region. The research meticulously fulfils its objectives, encompassing the assessment of wind potential based on multifaceted criteria, the development of a comprehensive wind atlas, and an intricate simulation of annual energy production. Moving beyond the technical realm, the study extends its scope to scrutinize the proposed electric vehicle charging stations from an economic perspective. This facet of the research aligns with global sustainability initiatives, adding a practical and applicable dimension to the findings. A notable outcome of the study is the strategic identification of five charging stations in the southern provinces of Thailand, namely Songkhla, Prachuap Khiri Khan, Surat Thani, Chumphon, and Narathiwat. This strategic placement is poised to play a pivotal role in supporting the escalating prevalence of electric vehicles in the region. The research pioneering in its nature, contributing significantly to the ongoing global transition towards renewable energy sources. The findings furnish foundational insights that contribute to both academic discourse and practical applications, not only in southern Thailand but also as a valuable reference for similar endeavours globally. In terms of specific values, the study conducts a detailed analysis of the average mean wind speed, wind power density, and other critical parameters. For instance, the average mean wind speed values for Chumphon, Narathiwat, Prachuap Khiri Khan, Songkhla, and Surat Thani are reported as 2.88 m/s, 4.18 m/s, 3.21 m/s, 5.43 m/s, and 2.16 m/s, respectively. Similarly, the average wind power density values for the mentioned locations are 77 W/m², 225 W/m², 139 W/m², 370 W/m², and 31 W/m², respectively. These metrics, along with other detailed statistical analyses, contribute to a nuanced understanding of the hybrid energy potential in southern Thailand.