Application of improved multiresolution technique for the MPS method to fluid lubrication

In this study, we improve a multiresolution method to reduce the computation time of fluid lubrication simulation based on a particle method by applying an implicit algorithm for viscosity calculation. The present method is based on the moving particle simulation (MPS) method and the overlapping particle technique (OPT), which is a multiresolution method for particle methods under unsteady states. The MPS method is used to solve the Navier–Stokes equation. The OPT is used to reduce the number of required particles and reduce the computation time. We improve the OPT by applying an implicit method for viscosity calculation to eliminate restrictions regarding time increment due to the diffusion number. In addition, we enable the particle size to be changed significantly between subdomains in the OPT. To validate the proposed method, we simulate the fluid lubrication of line contact in two dimensions until the flow reached a steady state. Consequently, it is shown that the pressure obtained using the proposed method agrees well with that obtained using the Reynolds equation. The computation time of a particle simulation using the improved multiresolution method is significantly shorter than that of a single-resolution simulation. In addition, the effects of particle size and subdomain size are validated in the fluid lubrication simulation using the OPT.