Hello: I work with sails, and i use it as parachute. I think in this case all the force over the surface must be from viscous terms ( no too much ciculation arround the sail appear), but when i make a force report the viscous force is very smaller than the pressure force. Does anyone knows why?

Other problem is that the pressure force on the sail and the sail shadow are of the same direction, and i think they must pe opossite.

When this problem appear i put a wall in a down stream inviscid flow, and the Dalambert paradox doesnt appear, There was force!. There are too many things i dont understand. Can anyone help me please?

Thanks

The dpm model has a minimum diameter for particles, I believe 1e-8 m. Try setting your particle size to 2e-8. If not acceptable for your model, I suggest contacting Fluent, there may be something you can change in a header file to decrease the minimum diameter.