Upper Ocean Response to Large Wind Farm Effect in the Presence of Surface Gravity Waves

Journal Article

Title: Upper Ocean Response to Large Wind Farm Effect in the Presence of Surface Gravity Waves
Authors: Paskyabi, M.; Fer, I.
Publication Date:
January 20, 2012
Journal: Energy Procedia
Volume: 24
Pages: 245-254
Publisher: Elsevier

Document Access

Website: External Link


Paskyabi, M.; Fer, I. (2012). Upper Ocean Response to Large Wind Farm Effect in the Presence of Surface Gravity Waves. Energy Procedia, 24, 245-254.

The upper ocean response in the presence of a wind farm is studied numerically, taking into account the effect of surface gravity waves. The farm geometry is a simplified rigid rectangle with characteristic size of L aligned with the wind direction. Assuming a typical wind deficit behind the farm, an analytical 2D U-shaped wake profile is applied to drive the upper ocean circulation. The shallow-water equations are modified to include farm characteristic length, wind-wave and wave-current momentum transfer to study the circulation in the rectangular ocean basin. Solutions of this modified expression as a function of the Rossby deformation radius confirm that the upper ocean response in the vicinity of a farm is strongly related to the wave effects. For the numerical study, the Regional Ocean Modelling System (ROMS) and a wave-modified finite volume technique are used that the wave-modified finite volume technique shows a reasonable agreement with ROMS simulation results. Numerical results for both linear and non-linear wave simulations show the existence of horizontal shear stress gradients related to the fluid motion, wave-induced stress and farm characteristic size. The wind and wave forcing by including wind stress, Stokes drift and wave-induced stress creates symmetrical, range-dependent dipoles in the upper ocean. The dipoles are sensitive to wind stress, wave forcing and L, and have tendency to become asymmetric with time. The near-surface Ekman current is affected significantly, and strong upwelling and downwelling occur. The linear numerical solver results, however, show that the pycnocline depth as a response of upper ocean to the farm becomes weaker after almost one day. Including non-linear term, horizontal diffusion, and bottom friction leads to a decrease in the strength of eddies. But, the amplitude of disturbances in the lee of the farm becomes weaker after almost three days.

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