Setting Up and Running an Internal Ventilation


Unlike external ventilation cases, the domain of the internal space needs to be defined manually.


The domain is of a cuboid shape, and defined in the same way as monitor regions. If your building is not a perfect cuboid shape, as is the case for this tutorial, define the domain to encompass all internal spaces. in:Flux will realize the shape of the building when the automatic meshing is performed.


Before continuing, ensure that the Building layer of the CAD model is visible in the 3D window and toggle off the Clip Plane before continuing.


To define an internal ventilation simulation:

  1. Choose Ventilation Simulation from the Select Item menu option

  2. Set the Type to Internal - this will make the CAD in the project transparent and display a yellow cuboid (the domain) which needs to be positioned around the turbine enclosure building.

  3. Under the Domain Size section use one of the pick tools and select the north-eastern corner of the building as shown in the figure below, or enter ( 94.5, 54.4, 0 ).


    Tutorial 9 - Figure 21 - Selecting the first definition point of the internal ventilation domain


  4. For the second point of the domain, select the other pick tool. Notice that there are red cross-hairs at various points around the model. Some of these represent the bounding box limits of the CAD model. Select the upper bounding box corner on the south-west side of the building, as in Figure 22, or you can enter (12.2, 10.5, 15) in the corresponding coordinate text boxes. The 'bump outs' of the building need to be included within the domain so that they are properly accounted for.


    Tutorial 9 - Figure 22 - selection of second definition point for internal ventilation domain using the red bounding box limit locations of the CAD model


  5. Ensure that the Ground Level is set to "0 meters" and click the box. This is necessary to set the lower bound of the domain.

  6. Check and make sure the Internal Point is where you desire to have the internal ventilation calculation and not within any CAD pieces (besides the building model itself). This tutorial will use the automatically assigned location of (53.35, 32.45, 7.5)

  7. In the Advanced options, set the Air Temperature as "10 C"

  8. Check that the HVAC dropdown menu has selected all 12 HVAC inlets and outlets, this should be confirmed by the text All HVAC being displayed, as in the figure below.


    Tutorial 9 - Figure 23 - Add Item Panel with entered information for the internal ventilation case


  9. Ensure that the Run Now checkbox is selected and click Add Item to start the simulation.




Return to the Project Items tab and after the simulation has initialized, double click on the Internal Ventilation text. Here you can watch the simulation and mesh progress with the calculation. Figure 24 below shows an orthographic top view of the currently calculated mesh at 30% completion.


Tutorial 9 - Figure 24 - currently calculated mesh for internal ventilation simulation


Let the simulation finish before continuing.