Getting Started with Simmodeler

Launching the Software

Once your environment is properly set, as shown in the convert step video, run: vglrun /projects/tools/SimmetrixTest/SimModeler7.0-190626/simmodeler in your terminal to launch simmodeler. Note that 7.0-190626 specifies the version of simmodeler you are launching.

Accessing the User Manual

When launching simmodeler, there is a blue question mark at the top right of the GUI. Click it and then click "launch manual" to open the user manual associated with the version of simmodeler you are using. This gives detailed descriptions of the various attributes and how they are defined to generate the desired mesh.

Applying Mesh Attributes

Volume Meshing

3D Boundary Layers

One of the most important aspects of volume mesh development is generating proper 3D boundary layers. This process is well outlined here from around 8:30 to 16:00. Note that all mesh attributes are set up under the "Meshing" tab.

Surface Meshing

2D and 1D Boundary Layers

To generate a proper surface mesh, it is important that both 2D and 1D boundary layers are implemented. Note that a 2D Boundary layer is defined on a surface and a 1D Boundary layer is defined on a line. The linked video shows both 2D and 1D boundary layers being applied to an airfoil and the mesh that results from these applied attributes.

Mesh Size and Face Extrusions

Two more useful attributes when generating proper surface meshes are defining Mesh Sizes and Face Extrusions on your desired surfaces. Face Extrusions are useful when adding refinement over curved surfaces. This process is well covered in this video.

Boundary conditions

Commonly boundary conditions include:

• comp3 - Specifies a 3D velocity vector
• comp1 - Specifies a 3D vector in which the velocity is constrained. Velocity normal to this vector is not directly affected. This is useful for creating slip walls and mimicking free stream regions.
• temperature - Sets the temperature of the wall. This is only needed for compressible cases.
• scalar_1 - Sets the scalar_1 / eddy viscosity to apply at a wall. For the Spalart Allmaras models, scalar_1 should be zero at physical walls where a boundary layer develops and 3 to 5 times the molecular viscosity at free stream boundaries (http://turbmodels.larc.nasa.gov/spalart.html)
• surf ID - Associates a number with one or more faces. This can then be read by Phasta and used to apply more complicated boundary conditions in software.
• natural pressure - Apply a mean pressure over a surface. The pressure at any particular point is still allowed to vary (someone verify).
• traction vector - ??. The zero vector is typically applied at outlet.
• heat flux - Specifies the rate at which heat is injected / removed (not sure which one) into / from the fluid domain. The value is almost always set to zero to create a perfectly insulated boundary.
• scalar_1 flux - set the flux of scalar_1 / eddy viscosity into / out of the domain (not sure which one). This is typically only used at outlets where high values of eddy viscosity have been convected downstream of turbulent walls. The value is almost always set to zero.
• turbulence wall - Indicates that a surface is to be included in the calculation of d2wall files (verify) which are then used by the Spalart Allmaras turbulence model to generate more physical turbulent kinetic energy production / dissipation budgets.

Incompressible

Common BCs used for an incompressible case with the S-A turbulence model

• Initial conditions
  • initial velocity (nonzero, typically small)
  • initial scalar_1 (3-5 times free-stream molecular viscosity)
• Inflow
  • Comp 3
  • scalar_1 (also 3-5 times free-stream molecular viscosity)
• Outflow
  • natural pressure (zero)
  • scalar_1 flux (zero)
  • traction vector (zero vector)
• Solid physical walls
  • Comp 3 (zero vector)
  • scalar_1 (zero)
  • turbulence wall (value unimportant; use zero)
• Impermeable slip walls
  • Comp 1 (zero in wall-normal direction)
  • scalar_1 flux (zero)
  • traction vector (zero vector)

Compressible

Common BCs used for a compressible case with the S-A turbulence model

• Initial conditions
  • initial velocity (nonzero, typically small)
  • initial scalar_1 (3-5 times free-stream molecular viscosity)
  • initial pressure
  • initial temperature

• Inflow
  • Comp 3
  • scalar_1 (also 3-5 times free-stream molecular viscosity)
  • temperature

• Outflow
  • (?) pressure or natural pressure (zero)
  • scalar_1 flux (zero)
  • traction vector (zero vector)
  • heat flux (zero)

• Solid physical walls
  • Comp 3 (zero vector)
  • scalar_1 (zero)
  • turbulence wall (value unimportant; use zero)
  • temperature or heat flux