# Is there an easy way to calculate the lift coefficient in PyFR?

I want to calculate the lift coefficient of some airfoil, is there any easy way I can get lift coefficient every “time steps”?

The fluid force plugin will get you the forces on a body and write them out to a CSV file every few time steps. From these you can trivially obtain the lift and drag coefficients.

Regards, Freddie.

The lift coefficient expresses the ratio of the lift force to the force produced by the dynamic pressure times the area. Can I get dynamic pressure every few time ? Besides, are the body forces mean pressure integral in one direction？

For the dynamics pressure you should use the characteristic denisty and velocity, anything else wouldn’t really make sense. For example, on a wing, the dynmaics pressure at the surface defined by 0.5\rho V^2 would be zero as the velocity at a viscous wall is zero.

The forces calculated are the pressure (Px and Py) and viscous forces (vx and vy) acting on the body resolved in x and y. They are the forces integrated over the area so it is the total force acting on the body, so not really a mean.

Thank you very much !

3 posts were split to a new topic: Lift coefficient and area