Hydrodynamic Drag loads formulation

Wind & Water Wave Energy
28

Dear Jason.Jonkman

  1. For IEA-15-240-RWT-UmaineSemi (Ptfmsway is particularly large - #3 by Cuizhi.Zhu), official tutorial calculates quadratic drag using AddBQuad ( IEA-15-240-RWT/IEA-15-240-RWT-UMaineSemi_HydroDyn.dat at master · IEAWindTask37/IEA-15-240-RWT · GitHub). Could you please provide some reference on how to calculate AddBQuad (0.5CdRhoA), especially for the area A in roll, pitch and yaw directions.
  2. In addition, does the AddBQuad have a reference point? I found AddBQuad directly multiplies with u|u| at PRP in HydroDyn.f90, but 0.5CdRhoA seems to have no pointing. Does the AddBQuad also apply to platform COG? Or how to calculate the AddBQuad at COG?
q(indxStart:indxEnd)   = reshape((/real(u%WAMITMesh%TranslationDisp(:,iBody),ReKi),rotdisp(:)/),(/6/))
qdot(indxStart:indxEnd)   = reshape((/u%WAMITMesh%TranslationVel(:,iBody),u%WAMITMesh%RotationVel(:,iBody)/),(/6/))
qdotsq(indxStart:indxEnd)   = abs(qdot(indxStart:indxEnd))*qdot(indxStart:indxEnd)
qdotdot(indxStart:indxEnd)   = reshape((/u%WAMITMesh%TranslationAcc(:,iBody),u%WAMITMesh%RotationAcc(:,iBody)/),(/6/))
m%F_PtfmAdd = p%AddF0(:,1) - matmul(p%AddCLin(:,:,1), q) - matmul(p%AddBLin(:,:,1), qdot) - matmul(p%AddBQuad(:,:,1), qdotsq)

Best regards,

Tianyuan