In Suspending Standing Waves, the artificial damping is introduced on the free surface of the restricted fluid region to suspend the overestimated standing wave motion within the restricted fluid region. This concept is extended in the moonpool hydrodynamic analysis to approximately account for the viscous damping effects. Similar to Equation 4–36, the artificial damping terms are added in Equation 4–116. The new free surface boundary condition on the mean free surface within all moonpools is expressed as:

(4–130)

where is the potential component due to a structure COG basic motion or an internal free surface pressure mode , is the diffraction wave potential, is the damping factor which is mainly determined by the model test involving the viscous scale effect (DNV, 2010) or the trial measurement, is a function related to the lowest natural frequency of the water motions in moonpools which is estimated by Equation 4–111 or Equation 4–112,

(4–131)