If one of the constituent materials has a transverse isotropic or orthotropic material law, a local orientation is needed to compute the flow. There are three different choices how to determine the local orientation.

The standard case is to use the orientation defined by the local orientation of the GAD objects, e.g., the direction of a fiber.

However, if the current structure was not generated using one of the structure generation modules, but imported from a 3D scan, GAD object information is not available. In such a case, the local orientation must be estimated from the image first, e.g., by using FiberFind or GrainFind. It is then possible to load the local orientation from a file generated by one of those modules, by selecting Load Orientation Information from File (*.gof).

The last option is to simply Use the Global XYZ-Coordinate System. In this case, the permeabilities entered in the Constituent Materials tab remain the permeabilities in the X-, Y- and Z-directions.