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.

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

2021 ◽  
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 ◽  
Horizontal Momentum ◽  
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 improvement of wind farm flow modelling. 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 for isolating the effects 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.

scholarly journals An experimental study of a three-dimensional pressure-driven turbulent boundary layer

1995 ◽  
Vol 290 ◽  
pp. 225-262 ◽  
Author(s):  
Semİh M. Ölçmen ◽  
Roger L. Simpson
Keyword(s):  
Boundary Layer ◽  
Shear Stress ◽  
Turbulent Boundary Layer ◽  
Coordinate System ◽  
Normal Stress ◽  
Three Dimensional ◽  
Mean Velocity ◽  
Vector Direction ◽  
The Mean ◽  
Pressure Driven

A three-dimensional, pressure-driven turbulent boundary layer created by an idealized wing–body junction flow was studied experimentally. The data presented include time-mean static pressure and directly measured skin-friction magnitude on the wall. The mean velocity and all Reynolds stresses from a three-velocity-component fibre-optic laser-Doppler anemometer are presented at several stations along a line determined by the mean velocity vector component parallel to the wall in the layer where the $\overline{u^2}$ kinematic normal stress is maximum (normal-stress coordinate system). This line was selected by intuitively reasoning that overlap of the near-wall flow and outer-region flow occurs at the location where $\overline{u^2}$ is maximum. Along this line the flow is subjected to a strong crossflow pressure gradient, which changes sign for the downstream stations. The shear-stress vector direction in the flow lags behind the flow gradient vector direction. The flow studied here differs from many other experimentally examined three-dimensional flows in that the mean flow variables depend on three spatial axes rather than two axes, such as flows in which the three-dimensionality of the flow has been generated either by a rotating cylinder or by a pressure gradient in one direction only throughout the flow.The data show that the eddy viscosity of the flow is not isotropic. These and other selected data sets show that the ratio of spanwise to streamwise eddy viscosities in the wall-shear-stress coordinate system is less scattered and more constant (about 0.6) than in the local free-stream coordinate system or the normal stress coordinate system. For y+ > 50 and y/δ < 0.8, the ratio of the magnitude of the kinematic shear stress |τ/ρ| to the kinematic normal stress $\overline{v^2}$ is approximately a constant for three-dimensional flow stations of both shear-driven and pressure-driven three-dimensional flows. In the same region, the ratio of the kinematic shear stresses $-\overline{vw}/-\overline{uw}$ appears to be a function of y+ in wall-stress coordinates for three-dimensional pressure-driven flows.

scholarly journals Comparison of Field Measurements and Large Eddy Simulations of the Scaled Wind Farm Technology (SWiFT) Site

2019 ◽  
Author(s):  
Myra L. Blaylock ◽  
Brent C. Houchens ◽  
David C. Maniaci ◽  
Thomas Herges ◽  
Alan Hsieh ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Wind Farm ◽  
Field Measurements ◽  
Operating Conditions ◽  
Large Eddy Simulations ◽  
Department Of Energy ◽  
Large Eddy ◽  
In Series ◽  
The Impact

Abstract Power production of the turbines at the Department of Energy/Sandia National Laboratories Scaled Wind Farm Technology (SWiFT) facility located at the Texas Tech University’s National Wind Institute Research Center was measured experimentally and simulated for neutral atmospheric boundary layer operating conditions. Two V27 wind turbines were aligned in series with the dominant wind direction, and the upwind turbine was yawed to investigate the impact of wake steering on the downwind turbine. Two conditions were investigated, including that of the leading turbine operating alone and both turbines operating in series. The field measurements include meteorological evaluation tower (MET) data and light detection and ranging (lidar) data. Computations were performed by coupling large eddy simulations (LES) in the three-dimensional, transient code Nalu-Wind with engineering actuator line models of the turbines from OpenFAST. The simulations consist of a coarse precursor without the turbines to set up an atmospheric boundary layer inflow followed by a simulation with refinement near the turbines. Good agreement between simulations and field data are shown. These results demonstrate that Nalu-Wind holds the promise for the prediction of wind plant power and loads for a range of yaw conditions.

scholarly journals Dynamics of Large Scale Turbulence in Finite-sized Wind Farm Canopy using Proper Orthogonal Decomposition and a Novel Fourier-POD Framework

2020 ◽  
Author(s):  
Tanmoy Chatterjee ◽  
Yulia T. Peet
Keyword(s):  
Boundary Layer ◽  
Power Generation ◽  
Atmospheric Boundary Layer ◽  
Large Scale ◽  
Wind Farm ◽  
Scaling Laws ◽  
Wind Farms ◽  
Orthogonal Decomposition ◽  
Pod Analysis ◽  
Proper Orthogonal

Large scale coherent structures in atmospheric boundary layer (ABL) are known to contribute to the power generation in wind farms. In the current paper, we perform a detailed analysis of the large scale structures in a finite sized wind turbine canopy using modal analysis from three dimensional proper orthogonal decomposition (POD). While POD analysis sheds light on the large scale coherent modes and scaling laws of the eigenspectra, we also observe a slow convergence of the spectral trends with the available number of snapshots. Since the finite sized array is periodic in the spanwise direction, we propose to adapt a novel approach of performing POD analysis of the spanwise/lateral Fourier transformed velocity snapshots instead of the snapshots themselves. This methodology not only helps in decoupling the length scales in the spanwise and the streamwise direction when studying the energetic coherent modes, but also provides a detailed guidance towards understanding the convergence of the eigenspectra. In particular, the Fourier-POD eigenspectra helps us illustrate if the dominant scaling laws observed in 3D POD are actually contributed by the laterally wider or thinner structures and provide more detailed insight on the structures themselves. We use the database from our previous large eddy simulation (LES) studies on finite-sized wind farms which uses wall-modeled LES for modeling the Atmospheric boundary layer laws, and actuator lines for the turbine blades. Understanding the behaviour of such structures would not only help better assess reduced order models (ROM) for forecasting the flow and power generation but would also play a vital role in improving the decision making abilities in wind farm optimization algorithms in future. Additionally, this study also provides guidance for better understanding the POD analysis in the turbulence and wind farm community.

Impact of Elevated Kevin-Helmholtz Billows on the Atmospheric Boundary Layer

2021 ◽  
Author(s):  
Qingfang Jiang
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Shear Layer ◽  
Exponential Growth ◽  
Three Dimensional ◽  
Large Eddy Simulations ◽  
Two Dimensional ◽  
Large Eddy ◽  
Saturation Stage ◽  
The Impact

AbstractThe impact of Kelvin-Helmholtz billows (KHBs) in an elevated shear layer (ESL) on the underlying atmospheric boundary layer (BL) is examined utilizing a group of large-eddy simulations. In these simulations, KHBs develop in the ESL and experience exponential growth, saturation, and exponential decay stages. In response, strong wavy motion occurs in the BL, inducing rotor circulations near the surface when the BL is stable. During the saturation stage, secondary instability develops in the ESL and the wavy BL almost simultaneously, followed by the breakdown of the quasi-two-dimensional KH billows and BL waves into three-dimensional turbulence. Consequently, during and after a KH event, the underlying BL becomes more turbulent with its depth increased and stratification weakened substantially, suggestive of significant lasting impact of elevated KH billows on the atmospheric BL. The eventual impact of KHBs on the BL is found to be sensitive to both the ESL and BL characteristics.

Research of Influence of Obstacles on Three-Dimensional Hill Wind Field

2013 ◽  
Vol 448-453 ◽  
pp. 1712-1715
Author(s):  
Rui Yang ◽  
Ting Ting Wang ◽  
Wei Wei Xia
Keyword(s):  
Flow Field ◽  
Wind Farm ◽  
Three Dimensional ◽  
Wind Farms ◽  
Wind Pressure ◽  
Wind Speeds ◽  
Wind Speed Distribution ◽  
The Hill ◽  
The Impact ◽  
Inlet Boundary Condition

At different wind speeds, in order to study the impact of obstacle size and distance to the bottom of the hill on wind farm, using Pro / E generates the model of hills and upstream obstacle, sinusoidal model was selected to the hill contour, then Fluent was adopted to analyze the flow field, turbulence model select the SSK k-ω, inlet boundary condition was exponential function. Wind speed distribution and wind pressure distribution of hill surface at each case were depicted by the simulation results; the obstacle of conducive for wind farms was obtained by comparing flow field distribution of each case.

scholarly journals Observed and simulated turbulent kinetic energy (WRF 3.8.1) overlarge offshore wind farms

2019 ◽  
Author(s):  
Simon K. Siedersleben ◽  
Andreas Platis ◽  
Julie K. Lundquist ◽  
Bughsin Djath ◽  
Astrid Lampert ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Wind Speed ◽  
Wind Farm ◽  
Wind Farms ◽  
Horizontal Resolution ◽  
Offshore Wind ◽  
Vertical Resolution ◽  
Offshore Wind Farms ◽  
The Impact ◽  
Simulated Wind

Abstract. Because wind farms affect local weather and microclimates, parameterizations of their effects have been developed for numerical weather prediction models. While most wind farm parameterizations (WFP) include drag effects of wind farms, models differ on whether or not an additional turbulent kinetic energy (TKE) source should be included in these parameterizations to simulate the impact of wind farms on the boundary layer. Therefore, we use aircraft measurements above large offshore wind farms in stable conditions to evaluate WFP choices. Of the three case studies we examine, we find the simulated ambient background flow to agree with observations of temperature stratification and winds. This agreement allowing us to explore the sensitivity of simulated wind farm effects with respect to modeling choices such as whether or not to include a TKE source, horizontal resolution, vertical resolution, and advection of TKE. For a stably stratified marine atmospheric boundary layer (MABL), a TKE source and a horizontal resolution in the order of 5 km or finer are necessary to represent the impact of offshore wind farms on the MABL. Additionally, TKE advection results in excessively reduced TKE over the wind farms, which in turn causes an underestimation of the wind speed above the wind farm. Furthermore, using fine vertical resolution increases the agreement of the simulated wind speed with satellite observations of surface wind speed.

scholarly journals The Impact of Height-Independent Errors in State Variables on the Determination of the Daytime Atmospheric Boundary Layer Depth Using the Bulk Richardson Approach

2021 ◽  
Vol 38 (1) ◽  
pp. 47-61
Author(s):  
Temple R. Lee ◽  
Sandip Pal
Keyword(s):  
Boundary Layer ◽  
Relative Humidity ◽  
Atmospheric Boundary Layer ◽  
Salt Lake ◽  
Weather Forecast ◽  
The United States ◽  
State Variables ◽  
Layer Depth ◽  
The Mean ◽  
The Impact

AbstractRawinsonde observations have long been used to estimate the atmospheric boundary layer depth (BLD), which is an important parameter for monitoring air quality, dispersion studies, weather forecast models, and inversion systems for estimating regional surface–atmosphere fluxes of tracers. Although many approaches exist for deriving the BLDs from rawinsonde observations, the bulk Richardson approach has been found to be most appropriate. However, the impact of errors in the measured thermodynamic and kinematic fields on the estimated BLDs remains unexplored. We argue that quantifying BLD error (δBLD) estimates is equally as important as the BLDs themselves. Here we quantified δBLD by applying the bulk Richardson method to 35 years of rawinsonde data obtained from three stations in the United States: Sterling, Virginia; Amarillo, Texas; and Salt Lake City, Utah. Results revealed similar features in terms of their respective errors. A −2°C bias in temperature yielded a mean δBLD ranging from −15 to 200 m. A +2°C bias in temperature yielded a mean δBLD ranging from −214 to +18 m. For a −5% relative humidity bias, the mean δBLD ranged from −302 to +7 m. For a +5% relative humidity bias, the mean δBLD ranged from +2 to +249 m. Differences of ±2 m s−1 in the winds yielded BLD errors of ~±300 m. The δBLD increased as a function of BLD when introducing errors to the thermodynamic fields and decreased as a function of BLD when introducing errors to the kinematic fields. These findings expand upon previous work evaluating rawinsonde-derived δBLD by quantifying δBLD arising from rawinsonde-derived thermodynamic and kinematic measurements. Knowledge of δBLD is critical in, for example, intercomparison studies where rawinsonde-derived BLDs are used as references.

scholarly journals MATHEMATICAL MODELING AND NUMERICAL STUDY OF ATMOSPHERIC BOUNDARY LAYER NEAR WINDFARMS

2021 ◽  
Vol 3 (65) ◽  
pp. 33-40
Author(s):  
Vladislav N. Kovalnogov ◽  
◽  
Yuriy A. Khakhalev ◽  
Ekaterina V. Tsvetova ◽  
Larisa V. Khakhaleva ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Wind Turbines ◽  
High Performance ◽  
Wind Farm ◽  
Numerical Study ◽  
Wind Farms ◽  
Time Range ◽  
Winter Period

The article analyzes Russian and foreign sources relating to the interaction of wind turbines with the surface layers of the atmosphere. It specifies the main problems of mathematical modeling of the atmospheric boundary layer near the wind farms due to adverse meteorological conditions, in particular, constant zero crossings in the autumn-winter period, various precipitation, a wide time range, air parameters, terrain and other features. The authors analyze the evolution of mathematical models of turbulence to describe the boundary layer near wind turbines from earlier to rapidly developing and currently used. To achieve greater accuracy and naturalism, it is proposed to use high-performance efficient algorithms based on combining scales and physics of phenomena. The authors propose a mathematical model for studying the state of the atmospheric polydisperse boundary layer under conditions of the Ulyanovsk wind farm, taking into account the dispersed particles in the flow, surface curvature, pressure gradient and other influences.

scholarly journals Turbulent kinetic energy over large offshore wind farms observed and simulated by the mesoscale model WRF (3.8.1)

2020 ◽  
Vol 13 (1) ◽  
pp. 249-268 ◽  
Author(s):  
Simon K. Siedersleben ◽  
Andreas Platis ◽  
Julie K. Lundquist ◽  
Bughsin Djath ◽  
Astrid Lampert ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Wind Speed ◽  
Wind Farm ◽  
Wind Farms ◽  
Horizontal Resolution ◽  
Offshore Wind ◽  
Vertical Resolution ◽  
Offshore Wind Farms ◽  
The Impact ◽  
Simulated Wind

Abstract. Wind farms affect local weather and microclimates; hence, parameterizations of their effects have been developed for numerical weather prediction models. While most wind farm parameterizations (WFPs) include drag effects of wind farms, models differ on whether or not an additional turbulent kinetic energy (TKE) source should be included in these parameterizations to simulate the impact of wind farms on the boundary layer. Therefore, we use aircraft measurements above large offshore wind farms in stable conditions to evaluate WFP choices. Of the three case studies we examine, we find the simulated ambient background flow to agree with observations of temperature stratification and winds. This agreement allows us to explore the sensitivity of simulated wind farm effects with respect to modeling choices such as whether or not to include a TKE source, horizontal resolution, vertical resolution and advection of TKE. For a stably stratified marine atmospheric boundary layer (MABL), a TKE source and a horizontal resolution on the order of 5 km or finer are necessary to represent the impact of offshore wind farms on the MABL. Additionally, TKE advection results in excessively reduced TKE over the wind farms, which in turn causes an underestimation of the wind speed deficit above the wind farm. Furthermore, using fine vertical resolution increases the agreement of the simulated wind speed with satellite observations of surface wind speed.

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