Drag Prediction on NASA Common Research Model Using Automatic Hexahedra Grid-Generation Method

To shorten the time to simulate fluid flows, we develop a fast automatic grid-generation tool, HexaGrid, that produces Cartesian grids with body-fitted layers. The objective of the present study is to apply automatic grid generation to the drag prediction of the NASA Common Research Model. First, we generate a grid following the 4th Drag Prediction Workshop gridding guidelines as far as possible and discuss the capabilities and limitations of the automatic method. Then, we validate the computational-fluid-dynamics results computed with the grid by comparison with other solvers and grid generators. The HexaGrid results agree well with the other results, with the differences in predicted drag being less than five counts except at the stall angle. Additionally, we compare separated flows at the stall angle. The separation lines and C-p distribution are found to be greatly affected by grid topology.