Gaurav Tomar (IIsc de Bangalor, Inde) - Smooth Particle Hydrodynamics for Free Surface Flows and Fluid Structure Interactions

Smoothed Particle Hydrodynamics (SPH) is a meshless particle based Lagrangian numerical method that has been in development for the past three decades. Commensurate with the exponential growth in computational power, SPH has been increasingly applied to solve problems of greater complexity in fluid mechanics, solid mechanics, interfacial flows, astrophysics and in interdisciplinary problems like fluid-structure interaction, granular flows, fracture mechanics, solidification etc.
Incompressible Smoothed Particle Hydrodynamics (ISPH), a variant of SPH, solves for a pressure field to achieve incompressibility as opposed to the original SPH method, which uses a stiff equation of state to achieve the same. ISPH is known to reduce spurious pressure fluctuations and also computational time. In this talk, several new improvements on the existing ISPH algorithm to simulate free surface flows will be presented. We will also discuss the various challenges encountered in implementing the ISPH algorithm in a computer program. We employ the proposed ISPH free surface algorithm to simulate water entry of projectiles. The flow features and energy transfer due to entry of solid bodies of different shapes, density and initial spin into water have been studied.

By performing a theoretical analysis, we demonstrate that although SPH is known to be inherently mass conserving, due to finite timestep updates, it does not conserve volume. This is equally applicable to other meshfree particle based methods as well. We propose a novel deformation-gradient based algorithm for better volume conservation. Finally, we will show that combining the ISPH algorithm proposed in this study with the weakly compressible SPH, simulations involving compressible-incompressible two fluid systems can also be performed.