The accurate prediction of flow phenomena using computational methods requires an appropriate modeling of the flow at the domain boundaries. Poinsot and Lele~(20) developed an approach to determine accurate conditions at the boundaries based on a characteristic analysis of the governing flow equations, referred to as the NSCBC (Navier-Stokes Characteristic Boundary Conditions) method. The derivation of the characteristic relations used within the NSCBC approach depends on the equations to be solved. The present paper focuses on the derivation of accurate boundary conditions based on the NSCBC approach for the recently developed CPM22 (Compressible Projection Method) approach, which is a pressure-based solution procedure for low and high Mach number flow phenomena. The implementation of the characteristic boundary conditions requires the pressure correction equation to be solved at the boundaries. Besides the temporal derivative of the pressure and the right hand side terms of the pressure correction equation, the pressure Laplacian needs to be calculated at the boundaries. This important issue is being addressed to within the present paper. After this, the derived boundary conditions are verified by means of a reflective and partially non-reflective behavior of the acoustic waves at the in-and outflow boundaries of a one-dimensional duct.
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