Mesh rupturing: A technique for geometry insertion and significant mesh movement

Many CFD simulations can require geometry motion that must be handled by both solver and meshing techniques. When the motion is small the interior mesh can be morphed with a variety of techniques such as elliptic or algebraic smoothing methods. If the motion is considered large these methods may fail and other techniques are employed to handle the displacing geometry. One option uses overset meshes while another remeshes the domain. These methods often employ non-conservative interpolation of flow solution variables between di?erent meshes. These interpolations, conservative or not, may have a significant impact on the accuracy of the time-dependent simulation. This paper describes a new grid technique that allows for significant geometry movement while maintaining a mesh that requires no interpolation between grids. In 2D this is done by identifying an existing line of points or segments in a background mesh and duplicating the segments. The duplicated points are projected onto either side of the geometry and the interior mesh is smoothed. As the geometry moves the splitting operation is repeated as new edges in front of the geometry are split and slide onto the geometry while edges near the back slide o? the geometry and are reconnected. This grid rupturing technique is described in detail and results from example problems are shown. The focus of the paper is on the grid methodology with some discussion on the corresponding flow solution techniques.