Solver: Models

Multiphase Flows

Multiple phases (fluids) are solved simultaneously with the coupled solver, providing substantial stability and run-time benefits. This ensures that the strong inter-phase coupling is resolved in a robust and efficient manner. Both Eulerian-Eulerian and Eulerian-Lagrangian multiphase are supported. Many years of experience in multiphase modeling are incorporated in ANSYS CFX.

ANSYS CFX Solutions for Multiphase Flows

Bubbly flows:

For flows where bubble size distribution is important, our unique and highly efficient way of simulating multi-sized bubbles includes break-up and coalescence phenomena. This provides you with accurate prediction of interfacial area, which could be important in unit operations such as gas lift reactors and contact tanks.

ANSYS CFX: Modeling Size Distribution for Bubbly Flows

Free surface flows:

ANSYS CFX simulates free-surface flow phenomena such as sloshing or filling. In addition to higher-order differencing schemes for the volume fraction equations, a surface-sharpening algorithm provides greater accuracy of the free surface by significantly reducing numerical diffusion. The code also includes surface tension effects that can be significant in microfluidics, reduced-gravity and capillary flows.

ANSYS CFX for Free Surface Flows
	The free surface capabilities in CFX allow simulation of filling of a gas tank. [Play MPEG-1 / Play RealMedia]

Discrete Particle Transport:

Analysis of many processes requires detailed understanding of the dynamics of discrete gas bubbles, liquid droplets, or solid particles. With ANSYS CFX's particle-transport model, you will gain information on the particle and it’s environment, such as erosion, age, diameter, temperature, and moisture content histories. Specific modules predict the combustion of oil droplets and pulverized coal, including devolatilization, char oxidation and coupling to gas-phase reactions. A spray-particle evaporation model also simulates heat transfer and evaporation processes in pure or multi-component materials.

ANSYS CFX Particle Transport Model
	Lagrangian Particle Tracking analysis of a wet SO2 scrubber modeled with CFX. Courtesy URS Corporation.

Rising or settling small particles or bubbles:

For disperse phases that equilibrate quickly with their surroundings, such as small bubbles or particles rising in tundishes or settling under gravity in clarifiers, use our Algebraic Slip Model. This is very efficient, as each species requires only one additional transport equation - its mass fraction - to be solved. Any number of species can be simulated, and the user can specify any slip velocity relationship.

Interphase Mass Transfer:

A general framework for Interphase Mass Transfer is provided in ANSYS CFX along with robust models for cavitation, condensation, evaporation and boiling.