Substances and Conditions

I am new to Caedium and still trying to figure out a few item in the user interface. I am creating all of my geometry in Pro|ENGINEER, creating a STEP file, and then importing the STEP file into Caedium.

I have several questions:

1. Once I assign a substance and provide an initial velocity, how can I confirm the substance and velocity? Is it possible to assign two substances to one volume OR assign the same substance twice? I just don't want to find myself accidentally doing this...thus the desire to confirm.

2. I am not always sure whether I should be assigning to an edge, face, or volume. Please provide some clarity. I understand that boundary conditions should be assigned to faces. But what about accuracy? Should I assign accuracy to faces, edges, or volume???

3. When I drag and drop the U vector field, do I assign this to edges, faces, or volume???

4. Once I drag and drop Residuals onto the window, should this automatically start the analysis? Or do I need to click PLAY?

5. Are the units always in metric? If so, can I change to inches, for example? Or do I just need to change the scaling factor under Preferences?

Neal Rosenblum

Substance, Accuracy, Fields, Simulation Control, and Units

STEP is the preferred format for geometry exchange with Caedium.

In answer to your questions:

1) It is only possible to have one Substance per volume. The most recent substance assignment will be current. To review the current substance on a volume:

  • Select the volume
  • In the Properties Panel select the volume tab (far left tab) and expand the Substance property to review the related properties

For more on selection see "Camera View Control and Entity Selection".

You can also delete (indicated by the pink highlight on a property) an assigned substance by selecting the property, right-clicking to launch the context menu, and selecting Delete.

2) Accuracy can be assigned to edges, faces, or the volume - it depends on where you want to cluster mesh cells for your accuracy requirements. Often you will want to assign accuracy constraints to faces of interest, e.g., as in the wheel faces in the section "Specify Meshing Parameters" for the tutorial "Flow Over a Rotating Wheel with Moving Ground". For more on accuracy see "Accuracy Tool".

3) You can assign a result field (e.g., U) to any geometry entity (vertex, edge, face, volume). Where do you want to see the results? Often it will be on faces as in many of the tutorials. For more details see "Using Fields and Variables".

4) Creating the Residuals monitor does not start the simulation. Clicking Run on the toolbar starts the simulation. Then the residual monitor will provide feedback on the progress of the various solvers for the simulation. For more on simulation control see "Run, Stop, and Lock Controls".

5) You can alter the displayed units in File->Properties, then in the Properties Panel set the name and scaling of your units you want to change. E.g., for inches set:
Units->Length = inches, Scale = 39.3701 (i.e., inches per SI unit [meter])

Note that changing the length units will also change the display units of any derived units such as viscosity. The scaling factor in the Preferences is for an internal length scale to maintain accuracy, unless you are modelling cities or micron scale geometry you shouldn't change it.