A new incompressible Navier-Stokes method with general hybrid meshes and its application to flow/structure interactions

Ahn, Hyung Taek
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A new incompressible Navier-Stokes method is developed for unstructured general hybrid meshes which contain all four types of elements in a single computational domain, namely tetrahedra, pyramids, prisms, and hexahedra. Various types of general hybrid meshes are utilized and appropriate numerical flux computation schemes are presented. The artificial compressibility method with a dual time-stepping scheme is used for the time-accurate solution of the incompressible Navier-Stokes equations. The Spalart-Allmaras turbulence model is also presented in the dual time-stepping form and is solved in a strongly coupled manner with the incompressible Navier-Stokes equations. The developed scheme is applied to the study of the inflow turbulence effect on the hydrodynamic forces exerted on a circular cylinder. In order to accommodate possible structural and mesh motion, the method is extended to the arbitrary Lagrangian-Eulerian (ALE) frame of reference. The geometric conservation law is satisfied with the proposed ALE scheme in moving mesh simulations. The developed ALE scheme is applied to the vortex induced vibration of a cylinder. A strong coupling of fluid and structure interaction based on the predictor-corrector method is presented. The superior stability property of the strong coupling is demonstrated by a comparison with the weak coupling. Finally, the developed methods are parallelized for distributed memory machines using partitioned general hybrid meshes and an efficient parallel communication scheme to minimize CPU time.