26.2.5 User Inputs

You can specify the discretization scheme and, for the pressure-based solver, the pressure interpolation scheme in the Solution Methods task page (Figure  26.2.1).

Solution Methods

Figure 26.2.1: The Solution Methods Task Page for the Pressure-Based Segregated Algorithm

For each scalar equation listed under Spatial Discretization ( Momentum, Energy, Turbulent Kinetic Energy, etc. for the pressure-based solver or Turbulent Kinetic Energy, Turbulent Dissipation Rate, etc. for the density-based solver) you can choose First Order Upwind, Second Order Upwind, Power Law, QUICK, Third-Order MUSCL, or (if you are using the LES turbulence model) Bounded Central Differencing (the default) or Central Differencing in the adjacent drop-down list. For the density-based solver, you can choose either First Order Upwind, Second Order Upwind, or Third-Order MUSCL for the Flow equations (which include momentum and energy). Note that the task page shown in Figure  26.2.1 is for the pressure-based solver.

If you are using the pressure-based solver, select the pressure interpolation scheme under Spatial Discretization, in the drop-down list next to Pressure. You can choose Standard, PRESTO!, Linear, Second Order, or Body Force Weighted.

The low order modification of PRESTO! can be applied by disabling the high order terms for the PRESTO! scheme. This is done using the following text command: solve $\rightarrow$ set $\rightarrow$ numerics When asked disable high order terms for PRESTO! pressure scheme?, enter yes. This modification can be used to stabilize the solution process when the pressure-based coupled algorithm is used and when the original PRESTO! scheme fails to converge.

If you are using the pressure-based solver and your flow is compressible (i.e., you are using the ideal gas law for density), select the density interpolation scheme under Spatial Discretization, in the drop-down list next to Density. You can choose First Order Upwind, Second Order Upwind, QUICK or Third-Order MUSCL. (Note that Density will not appear for incompressible flows.)

If you enable the VOF model while using the pressure-based solver, the volume fraction interpolation schemes that are available are Geo-Reconstruct, CICSAM, Modified HRIC, and QUICK.

If you change the settings for the Spatial Discretization, but you then want to return to ANSYS FLUENT's default settings, you can click the Default button.