Define the Fluid Model

Create the fluid domain, apply a material to it, and define the region where the flow occurs.

A fluid domain is a finite volume consisting of one or more fluid regions that are bounded by parts, exterior geometries, and openings. For internal fluid flow simulations, you must select the parts and define any openings to cap the total space that you mesh.

In this example, you create a fluid domain that exists internal to the heat exchanger's shell but external to its tubes. You bound the fluid domain using the inlet nozzle and the outlet nozzle (both of which are openings). Then, you define the space between the shell and the tubes as the fluid region. The fluid region is where water flows through the heat exchanger.

In this example, the fluid domain is a finite volume within the heat exchanger.

  1. From the Assistant, click Model.
    The Finite Element Model dialog box appears.
  2. From the Model options, select Create to create a finite element model (FEM).
  3. Name it Coolant Mesh, and click OK.

    Coolant Mesh A.1 appears in the tree.

    Tip: Press F3 to display the tree if it is not visible.

  4. From the Model section of the Assistant, click Model Setup .
  5. Apply the material definition for water to the fluid section associated with the fluid domain.
    1. Click to open the Material Palette.
    2. From the Material Palette, search for MynameEXAMPLE-Water.
      The Myname prefix is the duplication string you specified during Create the Simulation.
    3. Select MynameEXAMPLE-Water, and click OK.
      The app applies the material definition to the fluid section and closes the Material Palette.
  6. Expand the Fluid domain bounding parts section, and confirm that all four parts are selected.
  7. Specify the region that contacts the fluid.
    1. Expand the Regions section.
    2. Select the interior surface inlet nozzle.
      A glyph of a blue cube with a stem appears on that surface.

    3. Select or clear Flip direction to ensure that the cubical portion of the glyph is immersed inside the fluid region.
  8. Define the openings.
    1. Click in the Openings section.
    2. Select the inner edge of the inlet nozzle.
      A blue circular glyph appears in the center of the opening.

    3. Similarly, add an opening for the outlet nozzle.
  9. Click OK.