Q: How is the current/wave drag force on an area computed?
REV 7.01

A: The basic equation is:

   F = A * Ch * Cs * Rho * v **2 /2

Where

• A is an area,
• Ch is the height coefficient
• Cs is the shape coefficient
• Rho is the density of air, and
• v is the wind speed.

The meaning of A and the direction of the force depend on the current setting of a MOSES parameter. If you use -AF_ENVIRONMENT YES then the force is in the opposite direction of the wind and A is the area projected to the wind. If -AF_ENVIRONMENT NO was used, the the direction of the force is in the direction of the normal to the area and A is the area.