Yes you can. I don't have Flow Sim, just Flow Sim Express. The only way I can do external flows on a body is to put my model in a "virtual wind tunnel." I bascially created a long hollow rectanglular box and created inlet/outlet caps on either side, similar to simulating internal flows through a pipe. Then I put my model inside my "virtual wind tunnel." I created a mount to the floor for my model. Since I only have Flow Sim Express I can't simulate complex flows or get any true details about the flow field but I can at least see how/where my model affects the flow's velocity/pressure. It's crude but it works. If you have the regular Flow Sim I believe you can do external flows without the need for a "virtual wind tunnel."