ON INTERACTIONS BETWEEN WIND TURBINES AND THE MARINE BOUNDARY LAYER M. Salman Siddiqui ∗ Department of Mathematical Sciences NTNU Alfred Getz vei 1 7491, Trondheim, Norway Email: muhammad.siddiqui@math.ntnu.no Adil Rasheed CSE Group Mathematics and Cybernetics Sintef Digital 7034, Trondheim, Norway Email: adil.rasheed@sintef.no Mandar Tabib CSE Group Mathematics and Cybernetics Sintef Digital 7034, Trondheim, Norway Email: mandar.tabib@sintef.no Eivind Fonn CSE Group Mathematics and Cybernetics Sintef Digital 7034, Trondheim, Norway Email: eivind.fonn@sintef.no Trond Kvamsdal Department of Mathematical Sciences NTNU Alfred Getz vei 1 7491, Trondheim, Norway Email: trond.kvamsdal@math.ntnu.no ABSTRACT Most mesoscale models are developed with grid resolution in the range of kilometers. Therefore, they may require spatial averaging to analyze flow behavior over the domain of interest. In doing so, certain important features of sub-grid scales are lost. Moreover, spatial averaging on the governing equations results in additional terms known as dispersive fluxes. These fluxes are ignored in the analysis. The aim of this paper is to identify the significance of these fluxes for accurate assessment of flow fields related to wind farm applications. The research objectives are hence twofold: 1) to quantify the impact of wind turbines on MBL characteristics. 2) to account for the magni- tude of dispersive fluxes arising from spatial averaging and make a comparison against the turbulent flux values. To conduct the numerical study the NREL 5MW reference wind turbine model is employed with a RANS approach using k-ε turbulence model. The results are presented concerning spatially averaged velocity, wake deficit behind the turbine, dispersive and turbulent fluxes. ∗ Address all correspondence to this author. . NOMENCLATURE ρ Density(kg/m 3 ) z o Surface roughness Ω Angular rotation rate(rad /sec) u i Spatially filtered velocity in tensor form(m/s) u ′ Fluctuation in velocity with time(m/s) CFD Computational Fluid Dynamics RANS Reynolds Averaged Navier Stokes BEM Blade Element Momentum LES Large Eddy Simulation MBL Marine Boundary Layer NREL National Renewable Energy Laboratories INTRODUCTION With the size of operational offshore wind turbines increas- ing rapidly and already in the range of 100–150m, modeling of 1 Copyright © 2017 ASME Proceedings of the ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering OMAE2017 June 25-30, 2017, Trondheim, Norway OMAE2017-61688