Abstract:  A common defect of movingparticle semi-implicit method and other mesh free method such as SPH is that the pressure fluctuation is obvious and hard to resolve. A new method was proposed to reduce pressure fluctuation and has good effect. Divergence-free condition representing fluid incompressible is used to calculate pressure smoothly, then time average is used to deal with the calculation. There are two kinds of cases being numerically simulated which are water collapse and ship roll sloshing. Comparing to the original MPS method, the result from the new method is real, so that the new method has good practicability and reliability.

Key words: mesh free method, moving-particle semi-implicit(MPS)method, pressure smooth