I have a created a plane in my geometry at a certain cross-sectional location, but only want to take area average measurements of flow variables through a portion of that plane.
How can I do that if my orientation and/or desired surface is complex?
The best approach for creating this custom surface is probably to use a combination of CEL variables, contour plots and user surfaces :
1. Create a plane in the area of interest
2. Devise a dummy variable that will produce contours on that plane that can be used to isolate the desired subset area (this dummy variable can be derived from X,Y,Z or any flow variable,
3. Where ever possible, relationships where x,y,z are not arguments to another function should be used as these produce the cleanest contours
3. Create a contour plot of the new user variable. Work with this to adjust the ranges until the area of interest falls within one contour band. Take note of which contour # this is.
4. Create a user surface and set the Method to from Contour. Select the contour band # that defines the surface of interest.
5. The user surface will be defined as the area within that contour band
An example is attached that shows the application of this idea to a rectangular duct where the user wants to take measurements through only 1/2 duct, as defined by a diagonal slice through the cross section.
The attached files demonstrated how a transformed version of x*y is used to create diagonal contours which can then be further modified (via range adjustment) to isolate the required cross section of the duct.