Simulation of Drag Crisis Phenomena Over a 3D Teardrop-shaped Body

Thi-Hong-Hieu Le ； Tan-Phuoc Huynh ； Dinh-An Nguyen ； Ngoc-Hien Nguyen

《Journal of Aeronautics, Astronautics and Aviation》 55卷2期 Vol.55 No.2 (2023/06) Pp. 105-117

https://doi.org/10.6125/JoAAA.202306_55(2).01

摘要

Drag is a common topic in everyday activities and academic research. Drag crisis, which associates with the transition of boundary layers from laminar to turbulent, is a phenomenon that can gain advantages when increase velocity to the critical value for blunt bodies. Meanwhile, the appearance of laminar separation bubble (LSB) is thought to be the cause of drag crisis. The mechanisms, and structure as well as the influencing factors of laminar separation bubble have also been comprehensively studied. The paper focuses on the numerical approach to simulate three - dimensional (3D) teardrop model for the study of aerodynamic characteristic and LSB mechanisms. Results from the open-source code OpenFOAM are compared to that of the experiments. The 3D simulation results are exploited to analyze the velocity vector field, pressure distribution, turbulent flow field ... in the critical Reynolds regime, in which the drag crisis occurs, from Re = 4×10^4 to Re = 7×10^4. At the same time, the appearance of laminar separation bubble in the critical Reynolds regime is also analyzed. The results highlight the advantages of the transition k-ω SST turbulence model compared to the k-ω SST turbulence model in simulating the drag crisis phenomenon and the footprint of bubble formation.

關鍵字

Teardrop model ； Drag crisis ； Drag coefficient ； Critical Reynolds number ； Laminar separation bubbles

參考文獻

Bearman PW, “On vortex shedding from a circular cylinder in the critical Reynolds number regime,” Journal of Fluid Mechanics, Vol. 37 No. 3, 1969, pp. 577-585.

Rosko A, “Experiments on flow past a cylinder et very high Reynolds number,” Journal of Fluid Mechanics, Vol. 10, No. 2, 1961, pp. 345-356.

Williamson CHK., “Vortex Dynamics In The Cylinder Wake,” Annu. Rev. Fluid. Mech., Vol. 28, 1996, pp. 477-539.

Witts J, “The science of the Tour de France: Training Secrets of the world's best cyclists,” Bloomsbury, 2016.

Phuong D, Miau JJ, Zoghlami A, “An experimental study about the drag crisis phenomenon on teardrop model,” Journal of Aeronautics, Astronautics and Aviation, Vol. 51, No. 2, 2019, pp. 141-158.