Numerical investigation of two-dimensional axisymmetric and three-dimensional flow simulations over a benchmark underwater vehicle

Two-dimensional (2D) axisymmetric simulation is an efficient and time-saving computational fluid dynamics (CFD) technique when the body is axisymmetric, and the flow is along the length of the body. In the present paper, this technique is used to investigate turbulent flow around the bare hull configuration of the Defense Advanced Research Project Agency submarine model. Verification and validation of the results are done at three levels. The values of the total resistance, the distribution of the wall shear stress and the pressure on the surface, and the velocity profiles at various distances from the nose are compared with results obtained by using three-dimensional (3D) simulations and experimental results from the literature. The uncertainty in CFD results due to meshing is reported using Richardson Extrapolation. It is shown that the errors are minor, and the savings in computer memory and computation time are tremendous using 2D axisymmetric simulations. Good CFD practices essential for 2D axisymmetric simulations are also presented in this article, which will be helpful for the CFD community to conduct numerical investigations on any other axisymmetric bare hull bodies, such as torpedoes, missiles, submarines, and autonomous underwater vehicles in the future. Finally, the components of drag, coefficient of pressure, and wall shear stress at the highest speed (9.26 m/s) are also obtained using 2D axisymmetric simulation, which has not been previously reported in any other literature. The level of rigor in the 2D axisymmetric simulation reported here is rarely seen in recent literature.