Numerical Simulation of Cavitating Flows using Overset Mesh

Abstract

Modeling cavitation phenomenon can be a challenging prospect for numerical solvers because the available cavitation models require a fine-tuning of model parameters and a good quality mesh in cavitating zones. Cavitation often occurs in complex geometries such as nozzle injection systems, marine propellers or gear pumps and creating a good quality mesh in such geometries need high skill and enough time. Overset mesh simplifies the overall meshing process in complex geometries by allowing separately generated good quality component meshes, which later overlap on each other to form actual flow domain. The aim of this study is to validate the accuracy of the overset method for cavitating flow problems using a multi-phase RANS flow solver and a homogeneous mixture model. Cavitating flow inside a circular throttle injection system is validated against experiment where mass flow rates at the outlet are compared at different inlet pressures. Flow past a fully submerged wedge-shaped hydrofoil is analysed for different cavitation numbers and multiple angles of attack, where cavity shapes for both overset and non-overset meshes are compared with experimental images. Furthermore, supercavitation phenomenon for the flow past a circular disk is investigated where cavity length and cavity radius are validated against the empirical correlations proposed by different authors. This study also highlights the best practices for Schnerr-Sauer and Zwart-Gerber-Belamri cavitation models available in ANSYS Fluent with overset mesh.

Investigation of Inclusion Removal at Steel–Slag Interface toward a Small‐Scale Criterion for Particle Separation

“…As particle motion and the ambient flow should be symmetric regarding the axis that is through the sphere center and in the direction of motion, the physical configuration is simulated based on a simplified axisymmetric computational domain with wall‐boundary restriction on the other sides. A dynamic mesh technique—the overset grid [ 40 ] —is used to enable the particle motion, and meanwhile, it is able to maintain good mesh quality and provide more accurate calculations of surface tension effects throughout the process. As displayed in Figure 2b, the whole mesh consists of two parts: the large gray area which is the background mesh and represents the fluid domain and the component mesh around the particle surface.…”

Transient Cavitation and Friction-Induced Heating Effects of Diesel Fuel during the Needle Valve Early Opening Stages for Discharge Pressures up to 450 MPa

“…An overset method was used for resolving challenging problems like a bullet fling through the muzzle flow field [55]. Khaware et al [56] validated the accuracy of the overset method for cavitating flow problems using a multi-phase RANS flow solver and HEM in [56]. Koci et al [57] used the dynamic Cartesian cut-cell mesh moving method in the CONVERGE ® v2.3 CFD package for simulating the fuel injector nozzle flow using the finite volume methodology combined with the VoF method for simulating the multiphase flow.…”