24.5.8 Including the Immiscible Fluid Model

After you have selected the Eulerian multiphase model (Section  24.5), you can enable the Immiscible Fluid Model ( this section in the separate Theory Guide).

This model is only available with the Eulerian multiphase model. You cannot use this model with the Dense Discrete Phase Model. After selecting this model, VOF sharpening schemes such as Geo-Reconstruct and CICSAM become available for the Eulerian multiphase model. The default scheme with this model is Geo-Reconstruct. You can use the following drag laws with this model: symmetric, anisotropic-drag, user-defined, and none. The Default drag law with this model is symmetric. The anisotropic drag law is only compatible with the Eulerian multiphase model. When including turbulence, only the mixture turbulence model can be used with anisotropic drag.

The immiscible fluid model for the Eulerian multiphase allows you to use the sharpening schemes Geo-Reconstruct and CICSAM with the Explicit VOF option. This model should be enabled only for the cases requiring sharp interface treatment between phases.

If you want to use the anisotropic drag law, perform the following steps:

1.   Define the drag law in the Phase Interaction dialog box.

Phases Interaction...

2.   Click the Drag tab to display the Drag Coefficient inputs.

3.   For each pair of phases, select the appropriate drag law from the corresponding drop-down list.

• Select anisotropic-drag when there is higher drag in the normal direction to the interface and lower drag in the tangential direction to the interface. For details about this drag law, refer to this section in the separate Theory Guide.

  To specify the input parameters for anisotropic drag, you will need to use the
  /solve/set/mp-mfluid-aniso-drag text command. The options for an Anisotropic Drag Method of 0 (which is based on the symmetric drag), are as follows:

  Anisotropic Drag Method 
   [0] 
  
  Normal Interfacial Drag Friction Factor 
   [1000000] 
  
  Tangential Interfacial Drag Friction Factor 
   [10] 
  
  Length scale
   [0.0001]
  

  The options for an Anisotropic Drag Method of 1 are as follows:

  Anisotropic Drag Method 
   [0] 1
  
  Viscosity option
   [2] 
  
  Normal Interfacial Drag Friction Factor 
   [1000000] 
  
  Tangential Interfacial Drag Friction Factor 
   [10] 
  
  Length scale
   [0.0001]