Enhanced Dirichlet boundary condition in MPS method for free-surface flow with negative pressure

To enhance the computational accuracy and stability of the moving particle semi-implicit (MPS) method in simulating complex free-surface flow with negative pressure, an enhanced Dirichlet boundary condition (EDBC) for meshless particle methods is proposed. The method is based on the establishment of a virtual boundary using second-order linear fitting, and the Dirichlet boundary assignment is corrected according to the deviation vector from the virtual boundary to the free-surface particle. Some methods to reduce the fitting error are proposed to avoid surface destruction caused by introducing errors. The method is numerically verified using the hydrostatic pressure problem, Torricelli's experiment, and rotating square patch simulation. Furthermore, an inverted tank flow experiment is conducted to verify the accuracy and stability of the method. The results show that the proposed method exhibits significant stability in dealing with complex free-surface flow under negative pressure.