I am working on an small urban project to simulate wind. My CAD files are made in Rhinoceros and imported into CFD using ACIS format. When ever I open a new file and import the CAD file, I usually get warning messages about the file and sometimes after some geometry fixes, I can manage to make the simulation. But when I try to open a project which I have already made, I gt a message " CAD geometry cannot be read" and Autodesk CFD closes. Also, when I try to save as projects I get the same message.