Grid Generation Issues in the CFD Modelling of Two-Phase Flow in a Pipe

Abstract

The grid generation issues found in the 3D simulation of two-phase flow in a pipe using Computational Fluid Dynamics (CFD) are discussed in this paper. Special attention is given to the effect of the element type and structure of the mesh. The simulations were carried out using the commercial software package STAR-CCM+, which is designed for numerical simulation of continuum mechanics problems. The model consisted of a cylindrical vertical pipe. Different mesh structures were employed in the computational domain. The condition of two-phase flow was simulated with the Volume of Fluid (VOF) model, taking into consideration turbulence effects using the k-e model. The results showed that there is a strong dependency of the flow behaviour on the mesh employed. The best result was obtained with the grid known as butterfly grid, while the cylindrical mesh produced misleading results. The simulation was validated against experimental results.

Comparison of experimental and Computational Fluid Dynamics (CFD) studies of slug flow in a vertical riser

“…The details of this experimental facility may be found in Azzopardi et al [7] and [8][9][10]. In brief: the experimental test section of the facility consists of a transparent acrylic pipe of 6 m length and 0.067 m internal diameter.…”

“…Hence, a full 3-Dimensional flow domain, as shown in Figure 1, was considered based on the fact that the flow simulated has been found to be axisymmetric according to the conclusions of the previous experimental studies of Azzopardi et al [7] and [10] and In the present work, three The model riser flow geometry was built and meshed with Star-CD, then imported into Star-CCM+, where the computation and post-processing of the results were performed. The geometries of the mesh employed is the butterfly grid (O-grid), which has been successfully employed by [10], and [15][16]. Figure 3 shows the mesh for the riser used for the CFD simulation.…”

Computational fluid dynamics assessment of subcooled flow boiling in internal-combustion engine-like conditions at low flow velocities with a volume-of-fluid model and a two-fluid model

“…No account is thus given for the interaction between phases, and the velocity, pressure and temperature fields are the same for both phases. The flow equations are solved with a pressure-based segregated solver [14], and making use of a high resolution interface capturing scheme (HRIC) based on a compressive interface capturing scheme for arbitrary meshes (CISCAM) [15]. The boundary layer was modelled with hexahedral layers whose width is properly chosen according to the wall treatment adopted.…”

A Lagrangian-Lagrangian Model for Two-Phase Bubbly Flow around Circular Cylinder

“…Therefore, the velocity of bubble can be computed by solving the force balance over the individual bubble. (24) where, m B is the bubble mass, is the bubble velocity and are the forces due to drag, lift, buoyancy, virtual mass and pressure, respectively. The trajectory of bubbles can be determined from the bubble velocities as (25)…”

“…The other advantage of RVM relative to other flow simulation methods is that it is a mesh-free method. This characteristic solves a number of issues which exist in common CFD approaches for mesh generation [24]. Based on the algorithm of RVM, a specific number of vortices are generated and tracked based on a Lagrangian approach in each time step.…”