A Conservative Overset Mesh Scheme via Intergrid Boundary Reconnection on Unstructured Meshes

Abstract

A conservative overset mesh scheme has been developed for the simulation of unsteady time-accurate flows around multiple objects in relative motion based on an unstructured mesh methodology. To prevent spurious production of flow and to satisfy the conservation property across the overset mesh block boundary, a new intergrid boundary reconnection technique was developed. At each time step, blank region is created between mesh blocks after hole cutting, and this gap is refilled with new triangular elements generated by interconnecting the vertices distributed along the boundary of the mesh blocks. By executing this procedure, all mesh blocks are connected to each other instantaneously, and the complete flow domain can be calculated as a single-block mesh at each time step. Thus, the conservation property of flow over the global computational domain is automatically satisfied. This method was successfully implemented into a vertex-centered finite-volume flow solver. Several applications were made to validate the numerical behaviors of the present conservative overset mesh scheme. It was found that the present conservative overset mesh scheme coupled with the intergrid boundary reconnection technique is more accurate, efficient, and robust than the conventional non-conservative overset mesh scheme. Nomenclature sL,sR = left and right segment of cell edge ߱ = frequency of oscillation, 2κM∞ κ = reduced frequency M ∞ = freestream Mach number Re = Reynolds number based on the airfoil chord length Cp = pressure coefficient CL = lift coefficient CD = drag coefficient CM = moment coefficient y+ = non-dimensional wall distance X,Y = x and y coordinates of computational domain t * = non-dimensional time α = angle of attack, deg. I.