Examples of Using Data Mappers

This section provides two examples of multiphysics applications where you can use data mapping for explicit coupling.

  • Explicit coupling within Simcenter STAR-CCM+ (Conjugate Heat Transfer) -- Thermal analysis of a solid with flow-thermal analysis of fluid, for instance in under-hood analysis. The CFD in the fluid region can be solved in Simcenter STAR-CCM+ while the solid region is analyzed either in Simcenter STAR-CCM+ or in an external CAE package.
  • Explicit coupling between Simcenter STAR-CCM+ and Abaqus (Fluid Structure Interaction) -- Stress analysis of a solid coupled with CFD in fluid, for instance analyzing the flow around an F1 wing. In this case, Simcenter STAR-CCM+ solves the CFD and the structural analysis is either done using Simcenter STAR-CCM+ or an external CAE package.

Explicit Coupling Within STAR-CCM+

Consider a conjugate heat transfer (CHT) application in which both the solid and fluid regions are created and meshed in Simcenter STAR-CCM+. Instead of creating an interface as is traditionally done for implicit coupling, you can solve the fluid and solid regions separately as follows:
  1. Set up physics continua by selecting all the appropriate models to solve for flow and energy in the fluid and heat transfer in the solid.

    The idea is to solve solid and fluid separately, but couple them by exchanging boundary data at the common boundary.

  2. Create two surface data mappers from the Tools > Data Mappers node, one for mapping from solid to fluid (S2F) and the other for mapping from fluid to solid (F2S).
    In CHT applications, the data for exchange includes:
    • Local Heat Transfer Coefficient, and Local Heat Transfer Reference Temperature from fluid to solid
    • Surface Temperature from solid to fluid
  3. For the S2F mapper, choose the solid boundary as the source surface and the fluid boundary as the target surface, and select face stencils for both source and targets. In addition, choose Temperature as a scalar field for mapping.
  4. For the F2S mapper, choose the fluid boundary to be the source and the solid boundary to be the target, and again do face-to-face mapping. The scalar fields in this case are htc and Tref.

    The mappers are now set up to map data.

  5. Map once to create Mapped field functions.
  6. Use these Mapped field functions as boundary conditions:
    • For the solid boundary, choose Convection as the Thermal Specification and choose Field Function as the Method to apply heat transfer coefficient and ambient temperature. Then select the MappedLocalHeatTransferCoefficient and MappedLocalHeatTransferReferenceTemperature as the respective field functions.
    • For the fluid boundary, choose to apply the Dirichlet boundary condition using the Field Function method. In this case choose MappedTemperature as the applied field function.

    When the solver iterates, these fields are applied as boundary conditions.

    A java macro can be created to take the appropriate number of steps before performing a map operation. Perform a map operation to update the Mapped field functions. The coupling frequency can be determined based on the nature of the problem.

Explicit Coupling Between STAR-CCM+ and Abaqus

Consider an FSI analysis in which the solid region is modeled in Abaqus and the fluid region is modeled in Simcenter STAR-CCM+. The fluid model is created and meshed in Simcenter STAR-CCM+ as usual. The solid model is created in Abaqus.
  1. Set up the fluid physics continuum and specify appropriate solver properties. Also set up the morpher to account for solid displacement, as required for an FSI analysis.
  2. After setting up the Abaqus model, create an .inp file as well as a database file (.odb) with initial nodal displacements.
  3. Import the Abaqus .inp file into the simulation.
  4. Identify the interfacing surface pairs.
  5. Create two surface data mappers from the Tools > Data Mappers node, one for mapping from solid to fluid (S2F) and the other for mapping from fluid to solid (F2S).
  6. In FSI cases, the exchanged data are:
    • Pressure and Wall Shear Stress from fluid to solid
    • Surface Displacement from solid to fluid
  7. For the S2F mapper, choose the Abaqus surface as the source surface and the fluid boundary as the target surface, and choose the vertex source stencil and the face target stencil. In addition, choose Incremental Surface Displacement as a mapped vector field (this field is created when nodal displacements are imported from Abaqus).
  8. For the F2S mapper, choose the fluid boundary to be the source and the solid boundary to be the target, and choose face stencils for both source and targets. Choose Pressure as a scalar field and Wall Shear Stress as a vector field for mapping.

    The mappers are now set up to map data.

  9. Map using the S2F mapper to create Mapped field functions.
  10. Use these Mapped field functions as boundary conditions:
    • For the fluid boundary, choose Displacement as the Morpher specification. The displacement is applied using the mapped field function MappedIncrementalSurfaceDisplacement.
    • For the Abaqus imported surface, MappedPressure and MappedWallShearStress are exported to a separate .inp file and applied as loads on the Abaqus model. The details of using Abaqus are beyond the scope of this section.
  11. You can create a java macro to control the frequency of coupling depending on the nature of the problem. However, each time the coupling happens, perform the following steps:
    • Import new displacement data from Abaqus.
    • Map data to the Simcenter STAR-CCM+ boundary.
    • Map data from the fluid boundary to the imported surface.
    • Export the mapped data to the .inp file.
    • Apply the load on the Abaqus model.