Turbulent Flow Simulations of the Common Research Model Using Immersed Boundary Method

Transonic turbulent flows around the NASA Common Research Model are simulated to investigate the capability of the Cartesian-grid-based flow solver UTCart in three-dimensional high-Reynolds-number flow simulations. UTCart consists of an automatic Cartesian grid generator based on an octree structure and a compressible flow solver that uses an immersed boundary method with a turbulent wall function for the wall boundary condition. Using the UTCart grid generator, the medium grid (approximately 50 million cells) around the NASA Common Research Model is generated in 43 min. For the prediction of the drag coefficient at the cruise condition, the difference between the medium-grid result and the grid-converged value is 24 drag counts (8%). For the fine-grid (approximately 97 million cells) result, the difference reduces to 15 drag counts (5%). Although the drag coefficient is slightly overestimated, the componentwise aerodynamic coefficient shows a consistent trend of grid convergence. Furthermore, the qualitative flow features, including flow separation at high angles of attack, agree well with the experimental data and the computational results on conventional body-fitted grids.