The simplest hydrodynamic property specification is that of constant coefficients which remain the same throughout an analysis. Elements are grouped together into element sets in the usual manner, and the following five hydrodynamic coefficients for Morison’s Equation are specified on a set by set basis:
•Normal Drag. The drag coefficient for the direction normal to the section, denoted .
•Tangential Drag. The drag coefficient for the direction tangential to the section, denoted . This entry is optional, and if omitted defaults to zero.
•Normal Inertia. The inertia coefficient in the direction normal to the section, denoted . This entry is optional, and if omitted defaults to 2.0. Cnm is used in calculating the contribution to the inertia force normal to the element from the water particle acceleration. This term is integrated in the force vector on the right hand side of the equations of motion
•Tangential Added Mass. The added mass coefficient in the direction tangential to the section, denoted . This entry is optional, and if omitted defaults to zero.
•Normal Added Mass. The added mass coefficient in the direction normal to the section, denoted . This entry is optional, and if omitted defaults to (
). Cna is used in calculating the contribution to the inertia force normal to the element from the structure acceleration. This term is integrated into the mass matrix on the left hand side of the equations of motion.
•Drag Lift Coefficient. This input is optional and by default no drag lift is modelled. Refer to Drag Lift for further information on this feature.
The hydrodynamic force formulation in Flexcom is outlined in Hydrodynamic Loading.
•*HYDRODYNAMIC SETS is used to assign hydrodynamic coefficients to element sets. Specifically, the TYPE=CONSTANT input is used to assign hydrodynamic coefficients to element sets where these coefficients are independent of Reynolds number.