Step 10: Setup and Solution for the Eulerian Model

  The mixture model is a simplification of the Eulerian model and is valid only when bubble velocity is in the same direction as water velocity. This assumption can be violated in the recirculation pattern. The Eulerian model is expected to make a more realistic prediction in this case. You will use the solution obtained using the mixture model as an initial condition for the calculation using the Eulerian model.

1.   Select the Eulerian multiphase model.

Models Multiphase Edit...

(a)   Select Eulerian in the Model list.

(b)   Click OK to close the Multiphase Model dialog box.

2.   Specify the drag law to be used for computing the interphase momentum transfer.

Phases Interaction...

(a)   Retain the default selection of schiller-naumann from the Drag Coefficient drop-down list.

(b)   Click OK to close the Phase Interaction dialog box.

Note:   For this problem, there are no parameters to be set for the individual phases other than those that you specified when you set up the phases for the mixture model calculation. If you use the Eulerian model for a flow involving a granular secondary phase, you will need to set additional parameters. There are also other options in the Phase Interaction dialog box that may be relevant for other applications.

For details on setting up an Eulerian multiphase calculation, see this section in the separate User's Guide.

3.   Select the multiphase turbulence model.

Models Viscous Edit...

(a)   Retain the default selection of Mixture in the Turbulence Multiphase Model list.

(b)   Click OK to close the Viscous Model dialog box.

  The mixture turbulence model is applicable when phases separate, for stratified (or nearly stratified) multiphase flows, and when the density ratio between phases is close to 1. In these cases, using mixture properties and mixture velocities is sufficient to capture important features of the turbulent flow.

For more information on turbulence models for the Eulerian multiphase model, see this chapter in the separate User's Guide.

4.   Change the solution parameters.

Solution Methods

(a)   Select Multiphase Coupled from the Scheme drop-down list.

5.   Change the solution controls.

Solution Controls

(a)   Enter 40 for Courant Number.

(b)   Enter 0.5 for both Momentum and Pressure in the Explicit Relaxation Factors group box.

(c)   Retain the value of 0.4 for Volume Fraction in the Under-Relaxation Factors group box.

6.   Continue the solution by requesting 1200 additional iterations.

Run Calculation

7.   Save the case and data files ( tee2.cas.gz and tee2.dat.gz).

File $\rightarrow$ Write $\rightarrow$ Case & Data...