An Improved Algorithm Based On SIMPLE Algorithm

In this thesis,an improved SIMPLE algorithm is proposed to solve the checkerboard pressure fluctuation problem and the low convergence performance of SIMPLE algorithm.Incompressible flow is calculated,the governing equation is discretized by the finite volume method with conservation,and its variables are stored at the center of the grid.In this thesis,we combine the artificial compressibility with the pressure Poisson equation involved in the SIMPLE algorithm;this approach confronts a mass imbalance induced by the corrected velocity fields which can effectively assist the transformation between conservative and non-conservative(primitive)variables.An improved non-linear momentum interpolation dissipation scheme is used to calculate the cell-face velocities in order to form the fictitious mass source for the pressure-correction equation;the cell-face dissipation scheme is capable of eliminating non-physical oscillations due to the pressure-velocity decoupling.In order to verify the effectiveness of the improved algorithm,according to different physical parameters,a comparative assessment is carried out based on the buoyancy-driven square cavity flow,buoyancy-driven flow in a concentric annulus,viscosity-driven square cavity flow,simple pipe flow,backward-facing step flow and flow around an NACA0012 airfoil in collocated grid.Numerical experiments of buoyancy-driven flow,namely,natural convection in the square cavity and natural convection in an annular cavity;they are simulated using both SIMPLE and improved algorithms.The calculated speed of the improved algorithm is compared with the literature value.Afterward,convergence histories of these two algorithms are compared.Both algorithms also compute other test cases entitled the viscosity-driven cavity flow,simple pipe flow and backward step flow.Predicted velocity profiles are compared with literature data;both algorithms show favorable agreement with benchmark data and results are physically consistent.Finally,the flow around an NACA0012 airfoil is numerically analyzed and the pressure coefficient from the literature is compared with calculated results in this thesis.The pressure coefficient and streamline are calculated at different angles of attack;results are analyzed and compared.Of course,the improved algorithm allows large CFL(Courant,Friedrichs,Lewy)numbers to be used in the calculation.