On computational fluid dynamics modelling of crosswind effects for high-speed rolling stock

Diedrichs, Ben

doi:10.1243/095440903769012902

Cited by 61 publications

(52 citation statements)

References 20 publications

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“…Some other researchers have investigated the flow structures numerically to obtain a better understanding of the flow behaviour. Reynolds-Averaged Navier-Stokes (RANS) equations, time varying RANS (URANS) (Diedrichs, 2003;Durst, Khier and Breuer, 2000) and large-eddy simulation (LES) (Hemida, Krajnović and Davidson, 2005) were used. Since the cross-wind instability is a consequence of the unsteadiness of the flow field around the train, accurate time-dependent solution is necessary.…”

Section: Introductionmentioning

confidence: 99%

Exploring Flow Structures Around a Simplified ICE2 Train Subjected to A 30° Side Wind Using LES

Hemida

Krajnović

2009

Engineering Applications of Computational Fluid Mechanics

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Large-eddy simulation (LES) is conducted to investigate the flow around a simplified ICE2 train under side wind conditions at 30° yaw angle. The Reynolds number based on the height of the train and the free stream velocity is 2×10 5 . Two computations on two different meshes with different numbers of nodes are made to check the effect of the mesh resolution on the results. The fine and the coarse meshes give similar results meaning that the results are mesh independent. The results are also verified against available experimental data. Good agreement is obtained between the LES results and the experimental data. The LES results show that two flow regimes exist in the wake. The first flow regime consists of steady vortex lines in the upper part of the wake flow. It changes into unsteady shedding after a distance of about five train heights from their onset on the surface of the train. The second flow regime is the unsteady movement of the lower part of the wake vortices. They attach and detach from the surface of the train in a regular fashion. The time-averaged flow and the instantaneous flow around the ICE2 train at 30° yaw angle are explored.

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Section: Introductionmentioning

confidence: 99%

Exploring Flow Structures Around a Simplified ICE2 Train Subjected to A 30° Side Wind Using LES

Hemida

Krajnović

2009

Engineering Applications of Computational Fluid Mechanics

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“…A 100% variation of lift due to bogies and front spoiler, computed by CFD, is reported in [RRW04]. Finally, in [Die03] the effect of relative ground motion is estimated by CFD to reach 20%.…”

Section: Statistics Of the Aerodynamic Coefficientsmentioning

confidence: 97%

“…Even neglecting the flow in the underbelly region, which is extremely complex because of the presence of bogies etc., satisfying results are still missing and work is in progress, [Die03].…”

Section: Numerical Techniquesmentioning

confidence: 99%

Reliability based analysis of the crosswind stability of railway vehicles

Carrarini

2007

Journal of Wind Engineering and Industrial Aerodynamics

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“…Experimental studies have been undertaken, for instance, by Hemida & Baker [3,4] and by Haff et al [5]. Numerical studies with RANS based models have been reported by Diedrichs [6] and Khier et al [7]. Hemida & Krajnovic [8,9] used the large eddy simulation (LES) approach to study the influence of varying yaw angle and nose shape on flow structures around a simplified train model without inter-cap gaps and wheel bogies.…”

Section: Introductionmentioning

confidence: 99%

Comparison of Industrial and Scientific CFD Approaches for predicting Cross Wind Stability of the NGT2 Model Train Geometry

Fragner¹,

Weinman²,

Deiterding³

et al. 2015

Int J Railw Tech

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Safety assessments of cross-wind influence on high-speed train operation require a detailed investigation of the aerodynamic forces acting on a vehicle. European norm 14067-6 permits the derivation of required integral force and moment coefficients by experiments as well as by numerical simulation. Utilizing the DLR's Next Generation Train 2 model geometry, we have performed a case study comparing simulations with varying turbulence modeling assumptions. Because of its relevance for actual design, a focus lies on steady RANS computations, but more expensive unsteady RANS (URANS) and delayed detached eddy simulations (DDES) have also been carried out for comparison. Validation data for the exact same model configuration and moderate Reynolds numbers 250,000 and 450,000 is provided by side wind tunnel experiments. Particular emphasis is laid on simulating a yaw angle of 30• , for which a major vortex system on the leeward side of the train leads to sizeable uncertainties in predicted integral coefficients. At small to intermediate wind angles the flow remains attached and absolute errors in integral quantities decline with decreasing yaw angles. However, a consistent relative difference to the experimental results greater than 10% raises doubts about the general reliability of CFD methods, that are not capable of capturing laminar-turbulent transition, which is observed for scaled models in industry type wind tunnel experiments.1

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On computational fluid dynamics modelling of crosswind effects for high-speed rolling stock

Cited by 61 publications

References 20 publications

Exploring Flow Structures Around a Simplified ICE2 Train Subjected to A 30° Side Wind Using LES

Exploring Flow Structures Around a Simplified ICE2 Train Subjected to A 30° Side Wind Using LES

Reliability based analysis of the crosswind stability of railway vehicles

Comparison of Industrial and Scientific CFD Approaches for predicting Cross Wind Stability of the NGT2 Model Train Geometry

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