On The Application Of Wall Functions In Ship Viscous Flows

This paper presents a numerical study on quantifying the effect of wall function boundary conditions on the calculation of ship viscous flows based on the RANS equations at model and full scale Reynolds numbers. Grid refinement studies are performed for four eddy-viscosity models with and without wall function boundary conditions. In the latter case, the conditions are imposed at varying distance to the wall. The predicted friction and pressure resistance coefficients are dependent on the location where the wall functions are applied. The magnitude of this influence depends on the Reynolds number and/or the turbulence model, reaching in some cases changes exceeding 10%. It is also shown that wall function boundary conditions may have a strong influence on the predicted wake field, especially at model scale Reynolds number.