Check Valves

Check valves shut when the flow rate reaches a user-specified minimum value, and are often used to prevent back flow. Check valves can be represented using a resistance parameter, reducing the need to model the geometry.

To Assign a Check Valve

2. Open the Material quick edit dialog. There are several methods:
   • Left click on the part, and click the Edit icon on the context toolbar.
   • Right click on the part, and click Edit...
   • Right click on the part name under the Materials branch of the Design Study bar, and click Edit....
   • Click Edit in the Materials context panel.
3. Select one or more parts.
4. Select the database from the Material DB Name menu.
5. Select Check valve from the Type menu.
6. Select the material from the Name menu.
7. To specify the flow direction, open the pop-out dialog on the Flow Direction line, and select either the Global X, Y, or Z axes to choose a Cartesian direction as a flow direction. To graphically set the direction, click the Select Surface button, and select a surface. The flow direction will be normal to the selected surface.
8. Click Apply.

Parts assigned a check valve material should not be extrusion meshed. Autodesk® CFD does not support check valves with extruded elements.

To Create and Edit a Check Valve

1. To open the Material Editor, click Material Editor on the Materials context panel.
2. Click the List button.
3. Right click on a custom database, and select New material. Select Check Valve. Specify a Name.
4. Click the property button that is to be defined.
5. For each property: Select the Variation method, enter the appropriate value and units, and click Apply.
6. Optionally, click Save.
7. Click OK. The new material is available when the Materials quick edit dialog is opened.

The Default material database contains at least one instance of every material type. A convenient way to create a new material is to use a Default material as an example. Because these materials are read-only, use the Material Editor to copy the original into a custom database, and modify the copy. For more about creating a material from an existing material...

• A Check Valve material definition does not reference specific Cartesian components. Instead, the flow direction is specified when a check valve material is applied to a part.
• No other fluid property information is required to define a check valve. The Solver automatically applies the fluid property information from the surrounding fluid to the check valve material. For this reason it is very important that a check valve material contact only one fluid material type. If, for example, a check valve contacts air on one side and water on the other, an error will result, and the analysis will not run.
• Two parameters are required to define a check valve: the Full Open K Factor and the Cutoff Flow Rate.
• The Full Open K factor is used to simulate the fact that even a wide open valve causes loss to the flow. This value can be very small, but it is not recommended to use a value of 0.
• The Cutoff flow rate is the flow rate at which the valve begins to close.