Simcenter STAR-CCM+ How to automatically create of all edge-edge interfaces for Region-Based Shells

The information in this article applies to Region-Based shell regions. Please see the see also section for Parts-Based shell workflow. 

An edge/edge interface is created between two fluid film/solid shell regions. This interface typically needs to be created manually by selecting the edge boundaries, as the shell regions are created from the existing volume mesh. This article provides a java macro that automatically identifies and creates all the edge/edge interfaces.

An example geometry shown below is used to illustrate the use of the attached macro. The geometry consists of 5 regions, a shell region needs to be created of the outer walls of this duct. The region named “Expansion Section” has three separate boundaries for creation of shell region; all the rest of the regions have a single boundary for the creation of the shell region. Edge/edge interfaces will be required for shell region on contacting fluid regions.
   
To make use of the macro, it is required that the shell regions be created after initializing the region interfaces. This is done to identify the contacting regions. If the shell region is created after initializing the fluid interfaces, then the name of the contacting regions are transferred to the edge boundary name. This is shown by the image below. **Note: Interfaces can only be initialized if volume mesh exists.
  It is also a good idea and a requirement for the macro that a single shell region be created for each region e.g. the region named “Expansion Section” has three wall boundaries, a separate shell region can be created for each individual wall which would require creation of additional edge/edge interfaces. It is required for the macro that all wall boundaries in a region have a single shell region.

The use of the macro for different scenarios of shell regions is described below.

Fluid Film/Solid Shell:

• Initialize all the region interfaces.
• Select all the boundaries (from different regions) for which fluid film is required and select “Create Shell Region”. This will automatically create a shell region for each fluid region.

• Select all the shell regions and assign appropriate Fluid Film or Solid Shell continuum.
• Run the attached macro.

Fluid Film and Solid Shell:
Follow the steps below for a special case where we have fluid film and solid shell on the same boundary.

• Initialize all the region interfaces.
• Select all the boundaries (from different regions) for which Fluid Film is required and select “Create Shell Region”. This will automatically create a shell region for each fluid region, see image in the section above.

• Select all the shell regions and assign appropriate Fluid Film continuum.
• Select all the boundaries (from different Fluid Film shell regions) for which Solid Shell is required and select “Create Shell Region”.
• Select newly created shell regions and assign appropriate Solid Shell continuum.
• All the edge boundaries for the shell regions created from another shell region (such as the solid shell region in this case) are named “Internal edges” as shown in the image below.

• Run the attached macro.
• For the solid shell region (shell region created from another shell region), the macro will create interfaces between all boundaries named “Internal edges”. This means that the macro will create some additional edge interfaces that are not required. These interfaces will not be initialized and can be left in the simulation, alternatively the user can identify these uninitialized interfaces and delete them manually.

The example simulation file shown in this article is attached to this article for the case with Fluid Film and Solid Shell regions.

See also:
Simulating Physics > Multiphase Flow > Modeling Fluid Film > Setting Up a Fluid Film Simulation
How to set up a continuous fluid film between two regions?
How to create a solid shell to simulate a thin solid between two fluid regions
How to create a solid shell region and interface for modeling shell conduction
Parts Based Shells: Tips and Tricks for creating interfaces
Pre-Processing > Meshing > The Meshing Workflow > Creating Parts-Based Shells
Tutorials > Heat Transfer and Radiation > Parts-Based Shells: Exhaust Pipe