Hi

I am running a simulation of a 2D sail section. (essentially half an airfoil with a cylinder at the leading edge)

The strange problem I have is that when I use the 'force calculator' in Post I get a negative drag value on the mast. Interestingly if I simply reverse the sign on this value I get roughly reasonable results compared with experimental data. The sail itself gives results with the expected signs.

The pressure distribution looks correct on the mast i.e. it should be giving a posistive drag value. I notice from one of your posts that people have had problems with the 'force calcultor' before. Could someone advise if they have come accross a similar problem?

Many thanks

Iain

P.S. I have checked the surface normals are all consistent.

This is most likely a simple definition "error" i.e. whether the force is shown IRO the fluid domain vs. the adjacent solid domain.

Thanks Joe

I agree this seems to be the likely cause. I apologise but I am a relatively new user to CFX and am unsure how I can control whether the force is w.r.t the solid or fluid. Is it possible I have the sail and mast on opposite settings? (As I said before I have aligned all the surface normals, which was my first thought)

Many thanks for your patience

I am running ICEM and CFX-10.

Thanks again