Numerical analysis for wake flow field of Ahmed model based on a nonlinear-LRN/DES turbulence model
International Journal of Numerical Methods for Heat & Fluid Flow
ISSN: 0961-5539
Article publication date: 16 December 2021
Issue publication date: 28 March 2022
Abstract
Purpose
This paper aims to propose a precise turbulence model for automobile aerodynamics simulation, which can predict flow separation and reattachment phenomena more accurately.
Design/methodology/approach
As the results of wake flow simulation with commonly used turbulence models are unsatisfactory, by introducing a nonlinear Reynolds stress term and combining the detached Eddy simulation (DES) model, this paper proposes a nonlinear-low-Reynolds number (LRN)/DES turbulence model. The turbulence model is verified in a backward-facing step case and applied in the flow field analysis of the Ahmed model. Several widely applied turbulence models are compared with the nonlinear-LRN/DES model and the experimental data of the above cases.
Findings
Compared with the experimental data and several turbulence models, the nonlinear-LRN/DES model gives better agreement with the experiment and can predict the automobile wake flow structures and aerodynamic characteristics more accurately.
Research limitations/implications
The nonlinear-LRN/DES model proposed in this paper suffers from separation delays when simulating the separation flows above the rear slant of the Ahmed body. Therefore, more factors need to be considered to further improve the accuracy of the model.
Practical implications
This paper proposes a turbulence model that can more accurately simulate the wake flow field structure of automobiles, which is valuable for improving the calculation accuracy of the aerodynamic characteristics of automobiles.
Originality/value
Based on the nonlinear eddy viscosity method and the scale resolved simulation, a nonlinear-LRN/DES turbulence model including the nonlinear Reynolds stress terms for separation and reattachment prediction, as well as the wake vortex structure prediction is first proposed.
Keywords
Acknowledgements
The author(s) disclosed receipt of the following financial support for the research, authorship and/or publication of this article: This work was supported by the National Natural Science Foundation of China (no. 51975197) and the Science Research Foundation from the Education Department of Hunan Province, China (grant no. 16b148).
Citation
Zheng, L.D., Yang, Y., Qiang, G.L. and Gu, Z. (2022), "Numerical analysis for wake flow field of Ahmed model based on a nonlinear-LRN/DES turbulence model", International Journal of Numerical Methods for Heat & Fluid Flow, Vol. 32 No. 4, pp. 1348-1374. https://doi.org/10.1108/HFF-06-2021-0438
Publisher
:Emerald Publishing Limited
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