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An edge-based, three dimensional, characteristic-based upwind Roe/TVD unstructured flow solver with chemical kinetics and turbulence modeling for simulation of in-cylinder flowfields, CRUNCH, has been extended to improve computational efficiency and utilize multiple element types. Solution efficiency is achieved using an implicit GMRES time integration procedure which is capable of advancing the solution with very large CFL numbers. The grid motion is accomplished using an automated scheme wherein layers of cells are introduced and subsequently removed as valves increase/decrease lift and as the piston moves through its stroke. A multi-zone mesh framework allows various portions of the domain to slide past each other in a noncontiguous manner. Detailed simulations have been performed for the Ford Motor Company 4.6 liter, twin valve engine. Swirl, tumble, and cross-tumble histories compare well with prior simulations performed at Ford Motor Company.

An innovative approach for computing in-cylinder flowfields on tetrahedral grids is developed and demonstrated. The primary focus of the preliminary work presented in this paper is the development of an efficient mesh motion scheme for realistic engine geometries. An automated cell layering technique has been devised which embeds/deletes layers of tetrahedral cells as the cylinder flow domain expands/shrinks. The ability to compute in-cylinder flows using this new “multi-zone” concept is demonstrated for a twin-valve gasoline engine.