If a current is defined in the analysis, drag forces on Morison element due to current velocity are computed by using the Morison equation. In this case the structural velocity is taken as zero. Inertial forces are also not computed since the static solution is required.

Similarly, for static stability calculations, only the tube drag force term in the above equation is considered since the structure and fluid accelerations are not included.

The force arising from components of velocity in line with the tube axis is assumed to be zero.