Flow Design is virtual wind tunnel software for product designers, engineers, and architects. It models airflow around design concepts to help test ideas early in the development cycle.
At this point in time it is only available to students or educators. If you are a teacher or lecturer then this may be a great educational tool to show the power of cloud based computing to create perform iterative analysis of structures.
The software is a available here: http://www.autodesk.com/education/free-software/flow-design