I am working with a company that manufactures commercial lawn mowers. The deck is of course the most critical part of the machine. I am interested in doing some flow analysis of a 2 and 3 bladed deck. Is there software or services that deal with such a problem? How would you go about setting up the problem? Thanks.

Can you explain what the deck is? I guess its the shape of the "box" in which the blades rotate? This seems like an interesting problem. Do you know of any other companies which have worked on this problem using CFD? I would imagine grass and air as a mixture would be difficult to model. I don't know if its important to model both.

The deck is an oval shape. It may be about 4 or 5 inches tall and the number of blades is based on the width requirements. The air inlet is the bottom oval shaped edge of the deck and may have some restriction based on the conditions and density of the grass that is being cut. The outlet is a chute that exits at an angle out of the top, center, backside of the oval deck which leads to another fan and finally a catcher box.

The non-transient modeling of blades that I am aware of requires a high degree of solidity - you can't see through the fan. Your mower probably has two to four blades per spindal. Transient, although painful, will probably be the way to go.

If your blade paths do not overlap go find a code that has moving mesh functionality. If they do, you will either have to be extremely creative or find a code that has overset grid capability.