26.1.1 Choosing the Solver

To choose one of the solvers, you will use the General task page (Figure  26.1.1).

General

Figure 26.1.1: The General Task Page

To use the pressure-based solver, retain the default selection of Pressure-Based under Solver.

To use the density-based solver, select Density-Based under Solver.

After you have defined your model and specified which solver you want to use, you are ready to run the solver. The following steps outline a general procedure you can follow:

1.   (pressure-based solver only) Select the pressure-velocity coupling method (see Section  26.3.1).

2.   Choose the spatial discretization scheme and, for the pressure-based solver, the pressure interpolation scheme (see Section  26.2).

3.   (pressure-based solver only) Select the porous media velocity method (see
Section  7.2.3).

4.   Select how you want the derivatives to be evaluated by choosing a gradient option (see this section in the separate Theory Guide).

5.   Set the under-relaxation factors (see Section  26.3.2).

6.   (density-based explicit formulation only) Set up the FAS multigrid (see Section  26.4.4).

7.   Make any additional modifications to the solver settings that are suggested in the chapters or sections that describe the models you are using.

8.   Enable the appropriate solution monitors (see Section  26.13).

9.   Initialize the solution (see Section  26.9).

10.   Start calculating (see Section  26.11 for steady-state calculations, or Section  26.12 for time-dependent calculations).

11.   If you have convergence trouble, try one of the methods discussed in
Section  26.18.

The default settings for the first three items listed above are suitable for most problems and need not be changed. The following sections outline how these and other solution parameters can be changed, and when you may wish to change them.