Open Access

ARTICLE

Shear Flows in the Near-Turbulent Wake Region of High Speed Trains

Liang Ce, Yongchen Pan^*

China Academy of Railway Sciences Co., Ltd., Beijing, 100081, China

* Corresponding Author: Yongchen Pan. Email: .

(This article belongs to this Special Issue: EFD and Heat Transfer II)

Fluid Dynamics & Materials Processing 2020, 16(6), 1115-1128. https://doi.org/10.32604/fdmp.2020.010829

Received 31 March 2020; Accepted 24 August 2020; Issue published 17 December 2020

Abstract

Two flow cases for scaled high speed train models with different length are numerically analyzed in the framework of the improved delayed detachededdy simulation model. Specific attention is paid to the shear flows and related mechanisms in the near turbulent wake created by these moving models. In particular, a comparative analysis is made on the distributions of turbulent kinetic energy (TKE) and turbulence production (TP) in planes perpendicular to the streamwise direction. The numerical results suggest that, in the wake region very close to the tail, significant TKE and TP can be ascribed to the dynamic interaction between powerful eddies and strong shear, which explain why these quantities are sensitive to the shear strength. The shear flows are essentially governed by the boundary layers developing along the streamwise direction on the train surfaces, especially from the under-body region and the side walls. For other positions located in the downstream direction away from the tail, the interaction of vortices with the non-slip ground serves as a mechanism to promote transfer of energy from weak eddies to turbulence through the shear present in planes parallel to the ground.

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