Multi-Phase: Eulerian Flow in a Moving Wall Cylinder

Description

This project simulates Eulerian two-phase flow in a moving-wall cylinder using ANSYS Fluent, investigated through CFD analysis. The system consists of two fluids: water as the primary fluid, together with a secondary fluid (with a density of 2610 kg/m³ and a viscosity of 0.0026 kg/m·s).

The two-phase flow enters the chamber in the shape of a hollow cylinder. Water enters the system at a velocity of 0.629 m/s with a volume fraction of 0.67, while the secondary fluid enters at 0.099 m/s with a volume fraction of 0.23, under a relative pressure of 1,379,000 Pa.

The 3D geometry was created in Design Modeler. It consists of two concentric cylinders — an outer and an inner cylinder — with the two-phase fluid flowing through the annular space between the outer and inner walls; the inlet and outlet take the form of hollow circles. Meshing was performed in ANSYS Meshing using an unstructured grid, producing 11,880 elements.

Methodology

The Eulerian multiphase model is used to represent the flow of the two fluids through the system, treating each phase as an interpenetrating continuum with its own set of governing equations. The outer wall of the cylinder is stationary, while the inner wall is a moving wall rotating about the central axis of the cylinder at 30 rpm.

The model employs the standard k-omega turbulence model with the shear-flow correction option, together with the dispersed turbulence model for the multiphase flow.

Conclusion

This study investigates the effect of the rotating inner wall on the Eulerian multiphase turbulent flow.

On completion of the solution, two- and three-dimensional contours were obtained for pressure (for the mixture), velocity (for both the water phase and the secondary-fluid phase), the volume fraction of water and of the secondary fluid, and the path lines of each phase.

The two-dimensional contours are presented in two planes: the YZ section and the XY section. The YZ section is defined along the central axis of the cylinder, while the XY section is taken perpendicular to the central axis at distances of 4, 9, and 13.716 m (the outlet) from the inlet — allowing the development of the two-phase flow to be tracked along the length of the cylinder.