Setting Up Shell Region and Boundary Conditions

Create a shell region and define the boundary conditions.

In this tutorial, the binary liquid film forms on the Wetted Wall boundary of the Fluid region. A shell region is required for all boundaries on which the fluid film is to flow. You create this shell region from the Wetted Wall boundary.

To create a shell region and define the boundary conditions:

  1. Right-click the Regions > Fluid > Boundaries > Wetted Wall node and select Create Shell Region.


    A new shell region is added to the simulation tree. In addition, an interface is formed between the fluid region and the shell region, based on the geometry of the Wetted Wall boundary surface.



Assign the fluid film phase to the Wetted Wall Shell region:

  1. Select the Regions > Wetted Wall Shell node and set the Continuum to Fluid Film.


Specify the actual fluid film boundary conditions using the nodes within the Wetted Wall Shell region. These boundaries are formed from the edges of the original Wetted Wall boundary from which the shell region was created. By default all boundaries are set to no-slip wall, except the Interface to Fluid [In-place 1], which is set to the Fluid-Film Boundary type.

Change the boundary type of the Bottom edges, Symmetry edges, and Top edges boundaries to their appropriate types.

  1. Edit the Regions > Wetted Wall Shell > Boundaries node and set the boundary types as follows:

    Boundary

    Type

    Bottom edges

    Outlet

    Symmetry edges

    Symmetry Plane

    Top edges

    Mass Flow Inlet

The Wetted Wall is heated in one section only. You can define the heat flux in a field function.

  1. Right-click the Automation > Field Functions node and select New > Scalar from the pop-up menu.
  2. Rename the User Field Function 1 to Heat Flux Wetted Wall.
  3. Select the Heat Flux Wetted Wall node and set the following properties:
    Property Setting
    Function Name heatFluxWettedWall
    Definition ($$Position[2] <= 0.2)? 0 : 3000
  4. Set Dimensions as Length = -2 and Power = 1.


Specify the Wetted Wall heat flux.

  1. Edit the Regions > Wetted Wall Shell > Boundaries > Wetted Wall node and set the following properties:
    Node Property Setting
    Physics Conditions > Thermal Specification Condition Heat Flux
    Physics Values > Heat Flux Method Field Function
    Scalar Function Heat Flux Wetted Wall

Set the boundary conditions for the inlet of the fluid film shell.

  1. Edit the Boundaries > Top edges > Physics Values node and set the following properties:
    Node Property Setting
    Fluid Film Thickness Value 0.001 m
    Mass Flow Rate Value 0.015 kg/s
    Species Mass Fraction Value [0.5, 0.5]
    Total Temperature Value 293.15 K
  2. Save the simulation.