Suitability of preconditioning numerical method on NS equations for Compressible and imcompressible flows

A preconditioning method is introduced to the NS solver based on the dual-time iteration for calculating steady compressible flows. The eigenvalues of discrete equations may be balanced in this method. The stiffness of mpressible NS solver can be reduced for low-speed flow and the capability of the solver may be increased for low-speed flow. y comparing the Numerical results for the flow around cy the cylinder at Re=20, 40 with the experimental data, a good reement was obtained with a discrepancy of about 5%.