Numerical simulations of wind forces on Troll B

A three-dimensional computational fluid dynamics model is used to examine the air flow and forces (pressure and viscous) on a simplified geometrical description of the offshore production platform Troll B. The Navier–Stokes equations are used to describe the air flow except for flow through some specific regions of the platform such as the flare tower, where a Darcy formulation has been employed. The turbulence is modeled using the ‘two-equation’ renormalization group k-epsilon formulation. The equations are solved on an unstructured mesh using a control-volume based technique. The model is forced by prescribing wind velocity and turbulence level on the inflow open boundary where the vertical wind profile is designed to fit experimental data from wind tunnel tests. A no-slip boundary condition is applied at the sea surface and at the surface of the platform itself. To include effects of the presence of surface waves on the wind profile, a surface roughness length corresponding to a wave height of 2 m is introduced. Heeling of the platform due to wind forces is neglected. Flow fields and total drag/lift forces are computed for various wind directions. The results are compared with data from wind tunnel experiments of Troll B.