Load type > Viscous Drag Damping

Viscous drag damping element load is used for simulation of stream load on submerged floater and cables.

A variable stream over height is defined with variable and it is applied in static and dynamic calculation. Since structure is moving for time history calculation a relative velocity is considered for fluid drag force. Load is possible to define static and dynamic component that are directly computed in time response calculation. Element distributed load is calculated as:

q_i=0.5* ρ*C_d*D*(V^lc/rel)^α

Setting	Description
From, To, Step	Element series to be loaded
Assembly	Alternative to load assignment via element series: Name of the assembly to be loaded. The specified load is applied to every element of the specified assembly.
Variable name	Select defined variable profile. Stream velocity is defined as stream velocities (TabB) distributed over height (TabA).
Direction X, Y, Z	Global direction of stream.
Abscissa X, Y, Z	Global direction of height, used for variable positioning of stream.
Diameter (m)	Input user defined diameter.
Options: Mult. by CS width, Mult. by CS depth	Mult. By CS width: Cross section width B taken from cross section properties. Mult. By CS depth: Cross section depth H taken from cross section properties.
Drag coefficient	Average hydrodynamic drag coefficient.
Density of fluid	Density of fluid, usually water density.
Exponential law	Defined relationship between force and velocity, usually parabolic law is used.
Interaction factor	Interaction between moving structure and stream. This factor can include dynamic interaction depended on amplitude of motion, which is provided from hydrodynamic analysis.
Subdivision of load	Distributes load along the element with internal subdivision. Different gradients of stream will need higher subdivision of load.