Converting a Tetrahedral Mesh to a Prism-Tetrahedral Hybrid Mesh for FEM Accuracy and Efficiency Soji Yamakawa and Kenji Shimada GOAL Converting a tetrahedral mesh into a prism-tetrahedral mixed mesh. A prism-tetrahedral hybrid mesh yields a more accurate FEM solution with less computational time than a tetrahedral mesh. APPROACH The proposed method progressively inserts layers of prism elements in sweepable sub-volumes starting from a given cross section. Prism-Layer Insertion Input Tetrahedral Mesh 5,994 nodes 25,013 elements After 4 Layers are Inserted Final Prism+Tet Mesh 5,858 nodes 18,319 tet elements 1,960 prism elements 20,279 elements in total No more prism layer can be inserted without violating a prescribed quality threshold Frontal Plane Cutting Plane (Initial Frontal Plane) Cross Section Undo-able Data Structure Apply sequence of edge-collapse, local transformation, and smoothing operations to remove nodes that obstructs a new prism layer A new prism layer is inserted if: (1) All nodes obstructing the new layer insertion are removed, and (2) No element violates the quality threshold. Undo-able data structure overcomes the order-dependency problem of the mesh-modifying operations. If an element violates the quality threshold, the modifications must be retracted, and the proposed method tries a different sequence of mesh-modifying operations Effect of the Prism-Layer Insertion Error Tetrahedral Mesh Prism-Tet Hybrid Mesh 0.00000 0.00400 0.00800 0.01200 20000 40000 60000 80000 100000 # of elements Convergence of the Error Between Two Outlet Fluxes CFD Analysis of an Air-Conditioner Duct CFD Solution converges (reaches as accurate as it can) faster with a prism-tet hybrid mesh than a tetrahedral mesh. Structural Analysis of a Leg-Bone