# Solving force on a UDS - Fluent

Hello, I am solving a UDS for a new pressure term. However, I cannot appear to solve the lift and drag force coefficients from this UDS on the airfoil I am simulating flow for, like you can with the pressure. I was wondering if it was possible to obtain the lift and drag from a UDS?

Alternatively can I obtain the normal vector on the airfoil and calculate the lift and drag from that or can I substitute P=UDS using the define adjust. I've tried these both with no success. Any help would be appreciated. Thank you.

Pierce

## Comments

Amine,

Thanks for the quick feedback. The surface integral of the UDS works. It's the second part of your statement I'm unsure of. The area vector variable, where can I access and use this to perform my calculation.

Thanks worked great!

For anyone reading in future: In order to solve the Force on a UDS- create a custom field function: x-face-area * UDS/p_substitute , then perform a surface integral summation, this will give you the drag force.