Numerical Simulation of Flow in Complex Geometries by Using Smoothed Particle Hydrodynamics

Abstract

Because of its meshless nature, the smoothed particle hydrodynamics (SPH) is ideally suitable for simulating a complex flow with a free surface and moving boundary. In this paper, we used a parallelized SPH to analyze the complex flow in a two-dimensional (2D) model of a twin screw extruder with a narrow clearance. First, in order to validate our SPH algorithm, a “forced revolving moving boundary model” previously presented by us was also used in this work. The simulation results showed good agreement with the experimental results. In addition, the flow in the full-filled 2D twin screw extruder model was simulated by using SPH and FEM, respectively. The results of both SPH and FEM showed excellent agreement. Meanwhile, we studied the squeeze flow in the intermeshing region of the 2D model in both the full-filled state and half-filled state. We found that a larger velocity scale that is far higher than the circumferential screw velocity must be applied to estimate the speed of sound. Furthermore, the effects of viscosity and gravity on the flow in the partially filled 2D twin screw extruder model were analyzed. This work laid the foundation for the accurate analysis of flow in complex geometries by using SPH.

Simulation of non‐Newtonian flows in a partially filled twin‐screw extruder by smoothed particle hydrodynamics

“…In addition, different from the mesh‐based methods, SPH does not need an extra technology in simulating a free surface flow, that is, the algorithm is basically the same for partially filled or fully filled models. In our recent work, [ 23 ] we introduced a free surface flow experiment and validated the SPH algorithm.…”

“…In Eitzlmayer and Khinast's work, [ 20 ] an additional repulsive force is applied in the solid boundary. In our recent work, [ 23 ] we deal with the difficulty by setting a higher sound speed. By some numerical experiments, we finally choose 20 m/s as the final sound speed, both for the Newtonian flow cases and for the non‐Newtonian flow cases.…”

“…In recent years, the application of smoothed particle hydrodynamics (SPH) to simulate complex flows in TSE has attracted more and more interest. [20][21][22][23][24] SPH is a "real" meshfree particle method that is naturally adaptive and straightforward. In simulating complex flows with moving boundaries, a free surface, or multiphase interfaces, no extra technologies are required.…”

“…However, most studies mainly focus on the accuracy, stability, and computational efficiency of the algorithm. [20][21][22][23][24] In order to simplify the problem, the current applying of SPH in extrusion often simplified the fluid to be Newtonian flow. [20][21][22][23][24]28] However, the actual materials in extrusion such as polymers, food, and raw material of drugs are often non-Newtonian fluids.…”

“…[20][21][22][23][24] In order to simplify the problem, the current applying of SPH in extrusion often simplified the fluid to be Newtonian flow. [20][21][22][23][24]28] However, the actual materials in extrusion such as polymers, food, and raw material of drugs are often non-Newtonian fluids. In this work, non-Newtonian flows in TSE using SPH were studied.…”