24.3.3 Recommendations for Open Channel Innitialization

Once you have selected either the Open Channel Flow or the Open Channel Wave BC option in the Multiphase Model dialog box, then the Open Channel Initialization Method drop-down list appears in the Solution Initialization task page.

Solution Initialization

Figure 24.3.4: The Solution Initialization Task Page

Select an inlet zone from the Compute from drop-down list. You can now make your selection from the Open Channel Initialization Method drop-down list. If only the Open Channel Flow option was enabled, then you only have a choice of None or Flat. If you enabled Open Channel Wave BC, then your choices are None, Flat, or Wavy. The default initialization method is None.

If you initialize the solution using None, it has no effect as it does not use any open channel information from the selected zone. The Open Channel Initialization Method comes into effect when you select either Flat or Wavy.

This initialization is only valid for pressure-inlets and mass-flow inlets for open channel flow and velocity inlets for open channel wave boundary conditions. If the selected inlet zone does not have either open channel flow or open channel wave boundary conditions, ANSYS FLUENT will report an error message after you initialize the flow with open channel intialization method of Flat or Wavy.

Initialization will result in the volume fraction, X, Y, and Z velocities, and pressure being patched in the domain. The volume fraction will be patched in the domain based on the free surface level of the selected zone from the Compute from list. The velocities in the domain will be patched assuming the constant value provided for the velocity magnitude in the selected zone.

If you specify a profile for the velocity magnitude or direction vectors, the initialization will select the value for the velocity magnitude and direction vectors from only one face. Therefore the initialization may be inaccurate. However, generally, open channel inputs for velocity magnitude and direction vectors are constant.

The pressure which is patched is the hydrostatic pressure based on the free surface level specified in the selected zone.