scholarly journals An Analytical Model for the Regeneration of Wind after Exiting a Wind Farm

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 2071
Author(s):  
Brian Fiedler
Keyword(s):  
Boundary Layer ◽  
Pressure Gradient ◽  
Atmospheric Boundary Layer ◽  
Linear Model ◽  
Analytical Model ◽  
Environmental Conditions ◽  
Wind Farm ◽  
Length Scale ◽  
Equilibrium Calculation ◽  
Friction Pressure

The simplest model for an atmospheric boundary layer assumes a uniform steady wind over a certain depth, of order 1 km, with the forces of friction, pressure gradient and Coriolis in balance. A linear model is here employed for the adjustment of wind to this equilibrium, as the wake of a very wide wind farm. A length scale is predicted for the exponential adjustment to equilibrium. Calculation of this length scale is aided by knowledge of the angle for which the wind would normally cross the isobars in environmental conditions in the wake.

scholarly journals A Raman Lidar with a Deep Ultraviolet Laser for Continuous Water Vapor Profiling in the Atmospheric Boundary Layer

2020 ◽  
Vol 237 ◽  
pp. 03001
Author(s):  
Masanori Yabuki ◽  
Yuya Kawano ◽  
Yusaku Tottori ◽  
Makoto Tsukamoto ◽  
Eiji Takeuchi ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Water Vapor ◽  
Atmospheric Boundary Layer ◽  
Environmental Conditions ◽  
Raman Lidar ◽  
Backscatter Signal ◽  
Ultraviolet Laser ◽  
Deep Ultraviolet ◽  
Temperature Controlled

A Raman lidar with a deep ultraviolet laser was constructed to continuously monitor water vapor distributions in the atmospheric boundary layer for twenty-four hours. We employ a laser at a wavelength of 266 nm and detects the light separated into an elastic backscatter signal and vibrational Raman signals of oxygen, nitrogen, and water vapor. The lidar was encased in a temperature-controlled and vibration-isolated compact container, resistant to a variety of environmental conditions. Water vapor profile observations were made for twelve months from November 24, 2017, to November 29, 2018. These observations were compared with collocated radiosonde measurements for daytime and nighttime conditions.

scholarly journals A pressure-driven atmospheric boundary layer model satisfying Rossby and Reynolds number similarity

2021 ◽  
Vol 6 (3) ◽  
pp. 777-790
Author(s):  
Maarten Paul van der Laan ◽  
Mark Kelly ◽  
Mads Baungaard
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Atmospheric Boundary Layer ◽  
Wind Farm ◽  
Three Dimensional ◽  
Computation Time ◽  
Wind Farms ◽  
The Mean ◽  
The Impact ◽  
Pressure Driven

Abstract. Idealized models of the atmospheric boundary layer (ABL) can be used to leverage understanding of the interaction between the ABL and wind farms towards the improvement of wind farm flow modeling. We propose a pressure-driven one-dimensional ABL model without wind veer, which can be used as an inflow model for three-dimensional wind farm simulations to separately demonstrate the impact of wind veer and ABL depth. The model is derived from the horizontal momentum equations and follows both Rossby and Reynolds number similarity; use of such similarity reduces computation time and allows rational comparison between different conditions. The proposed ABL model compares well with solutions of the mean momentum equations that include wind veer if the forcing variable is employed as a free parameter.

Turbulence and Vertical Fluxes in the Stable Atmospheric Boundary Layer. Part I: A Large-Eddy Simulation Study

2013 ◽  
Vol 70 (6) ◽  
pp. 1513-1527 ◽  
Author(s):  
Jing Huang ◽  
Elie Bou-Zeid
Keyword(s):  
Boundary Layer ◽  
Large Eddy Simulation ◽  
Atmospheric Boundary Layer ◽  
Length Scale ◽  
Quasi Equilibrium ◽  
Turbulent Structures ◽  
Constant Length ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Stable Atmospheric Boundary Layer

Abstract This study seeks to quantitatively and qualitatively understand how stability affects transport in the continuously turbulent stably stratified atmospheric boundary layer, based on a suite of large-eddy simulations. The test cases are based on the one adopted by the Global Energy and Water Cycle Experiment (GEWEX) Atmospheric Boundary Layer Study (GABLS) project, but with a largely expanded stability range where the gradient Richardson number (Rig) reaches up to around 1. The analysis is mainly focused on understanding the modification of turbulent structures and dynamics with increasing stability in order to improve the modeling of the stable atmospheric boundary layer in weather and climate models, a topic addressed in Part II of this work. It is found that at quasi equilibrium, an increase in stability results in stronger vertical gradients of the mean temperature, a lowered low-level jet, a decrease in vertical momentum transport, an increase in vertical buoyancy flux, and a shallower boundary layer. Analysis of coherent turbulent structures using two-point autocorrelation reveals that the autocorrelation of the streamwise velocity is horizontally anisotropic while the autocorrelation of the vertical velocity is relatively isotropic in the horizontal plane and its integral length scale decreases as stability increases. The effects of stability on the overall turbulent kinetic energy (TKE) and its budget terms are also investigated, and it is shown that the authors' large-eddy simulation results are in good agreement with previous experimental findings across varied stabilities. Finally, Nieuwstadt's local-scaling theory is reexamined and it is concluded that the height z is not a relevant scaling parameter and should be replaced by a constant length scale away from the surface, indicating that the z-less range starts lower than previously assumed.

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