Effect of ocean turbulence on the hydrodynamic forces is currently an important issue for offshore installations in the GOM. The two focus areas are; 1 - completion of the CFD study in 2-D of the effect of upstream turbulence on the hydrodynamic forces exerted on cylinders, and 2 - study of the effect of upstream turbulence using 3-D CFD simulations. The project developed techniques for the simulating prescribed turbulence structures in the upstream flow field, as well as on simulations of flows around cylinders with and without turbulence being present in the current profile. Numerical implementation of turbulence necessitates investigation of required computational meshes and time-steps for the appropriate resolution of spatial and time scales of the problem.
Inlet turbulence profiles for two different Reynolds numbers of Re = 150 and Re = 1000 were tested. The first case essentially represents laminar flow with low upstream turbulence. In both cases, the simulations show similar patterns of response to the inlet turbulence. Investigation of the appropriate upstream boundary condition for the turbulence flow variable studied the influence of different values of this variable.
Then the 3-D turbulence was simulated with the corresponding hydrodynamic forces and compared to those obtained in the 2-D simulations.