On turbulence criteria and model requirements for numerical simulation of turbulent flows above offshore helidecks

Turbulence criteria for CFD of helideck flows in the Norwegian Norsok standard are reviewed and discussed. It is argued that the turbulence energy has benefits compared to the standard deviation of the vertical velocity component when used in criteria for turbulence in CFD. Revised expressions for the criteria are proposed, based on the turbulence energy. On the background of Norsok Standard C-004, requirements for turbulence modeling for helideck flow simulations are discussed. It is demonstrated that a requirement alone for using a Reynolds stress equation model, with no other specific requirements to the modeling, will not ensure improved CFD results compared to two-equation eddy-viscosity models. In addition, some issues of the turbulence terminology in Norsok Standard C-004 are discussed.