Preparing the Surfaces, Region, and Boundaries

There is only one boundary surface at this stage, but as you need to have separate surfaces for the inlet and outlet boundaries, it is necessary to split the surface before creating the volume mesh.

Split the surface:
  1. Right-click the Geometry > Parts > Cylinder > Surfaces > Faces node and select Split By Angle.
  2. In the Split Part Surfaces by Angle dialog do the following:
    1. Make sure that the Faces surface is selected in the view panel.
    2. Accept the default angle.
    3. Click OK.
    Information on the splitting action is shown in the Output window. Three part surfaces are shown in the object tree.
Create a region and associated boundaries from the geometry part and its surfaces:
  1. Right-click Geometry > Parts > Cylinder and select Assign Parts to Regions....
    The Assign Parts to Regions dialog appears.
  2. Select Create One Region for All Parts.
  3. Select Create a Boundary for Each Part Surface.
  4. Click Apply.
  5. Close the dialog.

    In the object tree, all of the surfaces appear as individual boundaries within the region.

Rename the single region:
  1. Rename the Regions > Region node to Fluid.

For this case generate a trimmed cell volume mesh aligned in the axial direction, with two layers of prism cells next to the cylinder wall. You do not wish to have prism cells on the inlet and outlet boundaries, however, and so to avoid this you must define the boundary types before you create the mesh. (The volume meshing tools do not generate prism layers on non-wall surfaces by default.)

  1. Rename the Regions > Fluid > Boundaries > cylinder.Faces 3 node to Outlet.
  2. With the Outlet boundary still selected, set the Type to Pressure Outlet.
  3. Rename cylinder to Wall.
  4. Rename cylinder.Faces 2 to Inlet.
  5. Set the Type to Velocity Inlet.