Abstract
In the present work, large eddy simulation coupled with immersed boundary (LES-IB) method is applied to simulate a backward facing step (BFS) flow, which is a canonical fluid dynamics problem involving flow separation, recirculation and reattachment that are common in many practical applications. The computed reattachment length, a primary parameter to evaluate the overall performance of the numerical method, shows promising accuracy in the present work compared to the alternative numerical simulations. Based on the mean velocity profiles at four representative locations, there is fairly well quantitative agreement among the present LES-IB, DNS and the experiment. The results reveal that the reverse flow in the reattachment region leads to little over-prediction of the reattachment length compared to the DNS result. Furthermore, second-order statistics are in good agreement with the reference data in spite of discrepancies in the recirculation and reattachment region owing to complex flow structure, verifying the accuracy of the present method. In addition, the instantaneous flow fields are also analyzed to show the capability of the present LES-IB method in vortex-capture, and one may see the transient process of flow separation based on the analysis of Lagrangian coherent structure (LCS).
| Original language | English (US) |
|---|---|
| Journal | Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science |
| DOIs | |
| State | Accepted/In press - 2020 |
Bibliographical note
Funding Information:In the present work, large eddy simulation coupled with immersed boundary (LES-IB) method is applied to simulate a backward facing step (BFS) flow, which is a canonical fluid dynamics problem involving flow separation, recirculation and reattachment that are common in many practical applications. The computed reattachment length, a primary parameter to evaluate the overall performance of the numerical method, shows promising accuracy in the present work compared to the alternative numerical simulations. Based on the mean velocity profiles at four representative locations, there is fairly well quantitative agreement among the present LES-IB, DNS and the experiment. The results reveal that the reverse flow in the reattachment region leads to little over-prediction of the reattachment length compared to the DNS result. Furthermore, second-order statistics are in good agreement with the reference data in spite of discrepancies in the recirculation and reattachment region owing to complex flow structure, verifying the accuracy of the present method. In addition, the instantaneous flow fields are also analyzed to show the capability of the present LES-IB method in vortex-capture, and one may see the transient process of flow separation based on the analysis of Lagrangian coherent structure (LCS). Backward facing step (BFS) flow immersed boundary (IB) method flow separation level-set method Lagrangian coherent structure (LCS) Tsinghua National Laboratory for Information Science and Technology https://doi.org/10.13039/501100004407 Beijing Natural Science Foundation 3182014 the National Natural Science Foundation of China 51776102 91852103 National Key R&D Program of China 2018YFB0606101 edited-state corrected-proof typesetter ts2
Funding Information:
The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was financially supported by National Key R&D Program of China (2018YFB0606101), the National Natural Science Foundation of China (Nos 91852103 and 51776102), Beijing Natural Science Foundation (3182014) and Tsinghua National Laboratory for Information Science and Technology. Dandan Yang also acknowledges China Scholarship Council for sponsoring her visit to the University of Minnesota.
Publisher Copyright:
© IMechE 2020.
Keywords
- Backward facing step (BFS) flow
- Lagrangian coherent structure (LCS)
- flow separation
- immersed boundary (IB) method
- level-set method