Inflow and outflow numerical simulation using least-square moving particle semi-implicit method on GPU

The implementation of the inlet and outlet boundaries is a key issue in the particle method. The boundary implementation at the inlet applicable to the original MPS method is difficult to be applied to the LSMPS method with higher accuracy. Advanced inlet and outlet boundary implementations are proposed in this study, including inlet boundaries with velocity profile, static pressure, total pressure, and deleted particle detection method for outlet boundary. Three pipe flow cases are used to verify the accuracy of inlet boundaries. For the velocity inlet boundary, the calculation of velocity near the central axis of the pipe has an average error of 0.17%. For the static pressure inlet boundary, the average error of pressure calculation near the central axis is 1.80%. For the total pressure inlet boundary, the numerical final velocity of water in the pipe has a 3.02% error compared with the theoretical result. A reservoir with two inlets and one outlet is used to verify the applicability of the above implementation in a 3D engineering case with five different inlet velocities. The results show that for different velocity inlets, the simulations obtain different filling times, and for velocity and pressure distributions near the outlet in accordance with the theoretical situation. The implementation proposed in this study can be used for practical engineering problems.