Numerical Simulation of the casting method Macrosegregation

The invention relates to a method for macrosegregation numerical simulation of a casting, aiming at solving the problems of long computation time, low precision and unsuitability for predication of castings with large size or complex shapes in the traditional macrosegregation. The method comprises the following steps of: performing mesh generation on a selected dendritic crystal growth microcosmic computation field; computing dendritic crystal growth shapes during alloy solidification under different maximum nucleation densities from a microcosmic scale, and outputting a solid phase fraction-average dendritic crystal solid phase feature diameter curve; performing macro-scale mesh generation on the casting; computing a mass, momentum, energy and composition conservation equation from a macrocosmic scale; computing a solid phase fraction by using a Newton downhill method; and computing a pasty zone permeability model from a macrocosmic scale by adopting a linear interpolation technologybased on the solid phase fraction-average dendritic crystal solid phase feature diameter curve under a given nucleation density. The method disclosed by the invention is suitable for macrosegregationnumerical simulation in sand casting and metal mold casting of various sizes and complex shapes.