Setting ramp parameters

The ramp parameters are available and required only for computation on the unstructured mesh. They don't affect computation on the structured mesh. On the unstructured mesh the ramp technique improves the stability of the solution procedure while the solution procedure slowly approaches the target physical situation.

Ramps allow a successive approximation to real material property values, if you start from scratch and do not want to change the properties in the Materials dialog. You can specify ramps for density, heat capacity and viscosity for an incremental variation of these material properties in pseudo-stationary computation. Usually, the viscosity value is increased in the beginning and then it is gradually reduced. Ramps for density and heat capacity start with a low value and are gradually increased. Again you define convergence criteria to determine when ramp steps shall be performed.

  1. Select Computation > Convection parameters.

    The Convection parameters dialog opens.

  2. Click on the Ramps tab.

    The Ramps tab in the Convection parameters dialog opens:

    Ramps tab in Convection parameter dialog 

    Figure 22. Ramps tab in Convection parameter dialog

  3. Activate the ramp(s) you want to run by clicking on the box in front of the respective ramp.

  4. Set the start factors for density, capacity, and viscosity as well as the multiplying factor.

  5. Ramp steps are performed, when the results are lower than the convergence criteria specified here:

    Set the convergence criteria for Momentum and Temperature.

  6. Click on Apply and Close.

    or

    Click on OK to apply the changes and to close the dialog.

Related Procedures

Setting convection parameters

Related Dialogs

Ramps