Once you have the relevant design variables grouped together, you can save the current state of those variables into a design variable file (*.des) that writes the variable information and current values to a text file. Simply click “Save” under the Pick tab in the Design Variables window to open a dialog to save or overwrite a *.des file. To load a design variable file, click “Load” under the Pick tab and choose a *.des file. Once accepted, the model will update the design variable parameters to the values stored in the design file.
Adding or removing design variables is very simple. To add a variable, you can choose the Container, Group, and Parm corresponding to the parameter you want and click “Add Variable” or, much easier, you can click on the parameter name in the component window and drag to the Design Variable List. Click on a parameter in the Variable List window to highlight and then click “Delete Variable” to remove it from the list. All stored design variables may be adjusted by slider or text entry under the Adjust tab.
Design Variables are a great way of collecting all of the important parameters in your model in a single location so you can quickly alter these settings without having to switch between components and tabs within the windows. You may also save and load Design files to quickly change multiple parameters at once. This is very useful for short, relatively simple trade space explorations that can be scripted.
Subsurfaces are lines, rectangles, or ellipses defined in the UW coordinates on an OpenVSP model surface. These features are honored by the CompGeom, CFD Mesh, and DegenGeom functions among others and may be used to model inlet/outlet boundary conditions, control surfaces, material properties, surface roughness, etc.
Linear parameter linking in OpenVSP establishes a linear relationship between any two parameters according to a scale and offset by B = A*Scale + Offset where B is the dependent variable and A is the independent or driving variable. Note that you should use Links when specific linear relationships, including equality, are needed in your model but should avoid linking every parameter by default. As with many features in OpenVSP, less is often more.
