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Numerical-Experimental Geometric Optimization of the Ahmed Body and Analyzing Boundary Layer Profiles

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Abstract

The trade-off between the fuel consumption and drag coefficient makes the investigations of drag reduction of utmost importance. In this paper, the rear-end shape optimization of Ahmed body is performed. Before changing the geometry, to identify the suitable simulation method and validate it, the standard Ahmed body is simulated using k − ω shear stress transport (SST) and k-epsilon turbulence models. The slant angle, rear box angle, and rear box length as variables were optimized simultaneously. Optimizations conducted by genetic algorithm (GA) and particle swarm optimization (PSO) methods indicate a 26.3% decrease in the drag coefficient. To ensure the validity of the results, a numerical-experimental study is conducted on the optimized model. Thereafter, the velocity profiles and flow structure in the boundary layers of the original geometry were compared to those of the optimized geometry at different sections. The results indicate that there are points where the velocity profile in the boundary layer can exceed the free stream velocity and return to it again, an overlooked observation in the previous studies. In addition to the streamlines, to better understand the formation of three-dimensional vortexes, the Q-criterion factor is computed and illustrated.

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Acknowledgements

The authors would like to acknowledge the invaluable assistance of Ali Kamali, Razie Aslani, and Navid Ehtiati, graduate students at Sharif University of Technology; Kaveh Ghorbanian, faculty member of Aerospace at Sharif University of Technology; Parisa M. Sharouni, MSc student at TMU; and Ehsan Allah Saadati, CFD expert. Their without-expectation helps are greatly appreciated.

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Authors and Affiliations

  1. Mechanical Engineering, Sharif University of Technology, 11155-1638, Tehran, Iran

    Mohamad Abdolmaleki, Ali Mashhadian, Sorosh Amiri & Hossein Afshin

  2. Vehicle, Fuel, and Environment Research Institute (VFERI), Tehran University, Tehran, Iran

    Vahid Esfahanian

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  1. Mohamad Abdolmaleki
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Correspondence to Hossein Afshin.

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Abdolmaleki, M., Mashhadian, A., Amiri, S. et al. Numerical-Experimental Geometric Optimization of the Ahmed Body and Analyzing Boundary Layer Profiles. J Optim Theory Appl 192, 1–35 (2022). https://doi.org/10.1007/s10957-021-01932-w

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