Research Highlights
Selected papers illustrating wind-farm turbulence, atmospheric-boundary-layer coupling, high-performance simulation, and canonical turbulence. For the complete chronological record, see the publications page.
Our research uses large-eddy simulation, direct numerical simulation, physical modeling, and high-performance computing to study turbulent flows in wind energy, atmospheric boundary layers, and canonical fluid systems. The highlights below show how we connect fundamental turbulence physics to predictive models for wind-farm performance, atmospheric exchange, flow variability, noise, and heat transport.
Large-eddy simulation of turbulent wakes in an extended wind farm. Such simulations reveal how turbine-scale wakes, farm-scale blockage, and atmospheric-boundary-layer dynamics interact.
Ten selected contributions are shown first. Additional papers are grouped in expandable themes below.
Featured highlights
Flow Structure and Turbulence in Wind Farms
Wind farms are multiscale turbulent-flow systems. This review synthesizes the physics of turbine wakes, wind-farm boundary layers, layout effects, and atmospheric coupling. It provides a conceptual foundation for treating large wind farms as flow systems that interact with the atmospheric boundary layer, rather than as collections of isolated turbines.
Key idea: Wind-farm performance is governed by interactions across turbine, farm, and atmospheric scales.
Modeling Multiscale Atmospheric Interactions in Wind-Farm Power Spectra
Wind-farm power varies over a wide range of time scales. This paper develops a physics-based model for how atmospheric motions across scales shape wind-farm power spectra, linking slow atmospheric variability, farm-scale coherence, and turbine-scale turbulent fluctuations.
Key idea: Wind-farm power spectra encode the multiscale interaction between atmospheric turbulence and turbine-array dynamics.
Understanding wind farm power densities
Large wind farms are limited by the rate at which kinetic energy is transported into the turbine layer. This paper analyzes wind-farm power density through the lens of atmospheric energy entrainment and farm-scale efficiency.
Key idea: Improving large wind farms requires understanding and enhancing energy entrainment from the atmospheric boundary layer.
From turbine-scale to wind farm-scale wake recovery: Understanding the transition
Wake recovery changes character as isolated turbine wakes become farm-scale wakes. This study shows that turbine-scale recovery is driven mainly by spanwise turbulent entrainment, while farm-scale recovery depends on vertical entrainment and mechanical energy fluxes.
Key idea: Turbine-wake recovery and wind-farm-wake recovery are physically different problems.
Recent highlights
Impact of atmospheric turbulence on performance and loads of wind turbines: knowledge gaps and research challenges
This community review identifies how atmospheric-boundary-layer turbulence affects wind-turbine power production, loads, design, and wind-farm operation, and outlines key knowledge gaps.
Mean turbulent momentum fluxes and wind deficits in nocturnal stable atmospheric boundary layers
This paper connects stable stratification, turbulent momentum fluxes, and wind deficits in nocturnal boundary layers. The implications for offshore wind-farm inflow and wake behavior are an application inference rather than a result tested in this paper.
The global properties of nocturnal stable atmospheric boundary layers
This study analyzes the global structure of nocturnal stable atmospheric boundary layers and clarifies how stratification modifies turbulent transport and boundary-layer depth.
Simulation and modeling of wind farms in baroclinic atmospheric boundary layers
This work extends wind-farm simulation and modeling to baroclinic boundary layers, where wind direction and shear vary with height and alter wake recovery and power production.
Modeling wind farm noise emission and propagation: Effects of flow and layout
This paper models how wind-farm layout and flow conditions jointly determine turbine noise emission and propagation.
Low-frequency wind speed variations and their impact on wind farm performance
This study examines how slow atmospheric wind-speed variations affect wind-farm power production and farm-scale performance variability.
Further highlights by theme
Wind-farm turbulence and wake physics
Wake interaction, farm-scale recovery, and turbulent energy replenishment.
Large wind farms operate in a multiscale turbulent flow. Turbine wakes interact with neighboring turbines, merge into farm-scale wakes, and alter the exchange of momentum between the surface layer and the atmosphere above. We use large-eddy simulation and reduced-order modeling to understand these processes and improve predictive wind-farm models. See also the wind-farm LES and analytical wind-farm modeling pages.
- Flow Structure and Turbulence in Wind Farms - also featured above.
- From turbine-scale to wind farm-scale wake recovery - also featured above.
Effects of turbine spacing on the power output of extended wind-farms
This study uses large-eddy simulation to quantify how streamwise and spanwise turbine spacing influence the power output of very large wind farms. It links layout effects to the vertical flux of kinetic energy into the turbine region.
Key idea: Wind-farm layout controls not only local wake losses but also farm-scale replenishment of kinetic energy from above.
Comparison of wind farm large eddy simulations using actuator disk and actuator line models with wind tunnel experiments
This paper compares actuator-disk and actuator-line turbine models in LES against wind-tunnel measurements. It clarifies when simplified turbine representations are sufficient and when more detailed actuator-line modeling is needed.
Key idea: High-fidelity wind-farm simulations must be validated against experiments to ensure that wake physics and turbine interactions are captured correctly.
Atmospheric coupling and wind-energy limits
Stability, low-level jets, geostrophic forcing, and available kinetic energy.
Wind-farm performance is controlled by the atmospheric boundary layer. Stability, low-level jets, baroclinicity, geostrophic forcing, and turbulent momentum transport determine how much kinetic energy is available to the farm and how quickly wakes recover. See also the turbulent boundary layer page.
- Understanding wind farm power densities - also featured above.
- The global properties of nocturnal stable atmospheric boundary layers, and Mean turbulent momentum fluxes and wind deficits in nocturnal stable atmospheric boundary layers - also listed under Recent highlights above.
Universal Wind Profile for Conventionally Neutral Atmospheric Boundary Layers
This study develops and validates a universal velocity profile for conventionally neutral atmospheric boundary layers. It provides a theoretical basis for wind profiles relevant to wind-energy applications and atmospheric modeling.
Key idea: Accurate wind-farm modeling requires physically consistent descriptions of the atmospheric boundary layer, not only turbine-wake models.
Impact of Negative Geostrophic Wind Shear on Wind Farm Performance
This paper shows how the direction of geostrophic wind shear in the atmosphere changes wind-farm power production, highlighting the importance of atmospheric forcing beyond idealized neutral or stable boundary layers.
Key idea: Large wind farms are sensitive to the vertical structure of geostrophic forcing, not only to the near-surface wind speed.
Effect of low-level jet height on wind farm performance
This work shows how the height of a nocturnal low-level jet relative to the turbine rotor changes wake recovery and wind-farm performance.
Key idea: Atmospheric structure can directly determine whether wake recovery improves or degrades.
Multiscale wind-farm variability
Power fluctuations driven by atmospheric and array-scale motions.
Wind-farm power varies over seconds, minutes, hours, and longer atmospheric time scales. We study how coherent atmospheric motions, turbulent structures, and turbine-array interactions shape aggregate power fluctuations.
- Modeling Multiscale Atmospheric Interactions in Wind-Farm Power Spectra - also featured above.
- Low-frequency wind speed variations and their impact on wind farm performance - also listed under Recent highlights above.
Temporal structure of aggregate power fluctuations in large-eddy simulations of extended wind-farms
This paper characterizes the temporal spectrum of aggregate power output fluctuations from large-eddy simulations of extended wind farms.
Key idea: Aggregate wind-farm power fluctuations have a distinct spectral signature that reflects farm-scale turbulence.
A wavenumber-frequency spectral model for atmospheric boundary layers
This paper develops a wavenumber-frequency spectral model for turbulence in atmospheric boundary layers. Wind-energy applications are motivated, but power forecasting is not demonstrated.
Key idea: A compact spectral model connects spatial and temporal atmospheric-turbulence statistics and can support later wind-energy applications.
Wind-farm noise and environmental impact
Wake, layout, terrain, and atmospheric effects on sound.
Wind-farm flow physics affects more than power production. Wakes, turbine layout, atmospheric turbulence, and rotor operating conditions influence noise emission, propagation, and amplitude modulation.
- Modeling wind farm noise emission and propagation: Effects of flow and layout - also listed under Recent highlights above.
Wake-induced variations in noise levels and amplitude modulation for two interacting wind turbines
This study examines how the wake of an upstream turbine changes the noise level and amplitude modulation of a downstream turbine. It establishes a mechanistic link between wake interaction and acoustic variability; perceived-noise effects were not measured.
Key idea: Turbine wakes can modify downstream noise characteristics, creating flow-dependent acoustic variability.
Three-dimensional effects of the wake on wind turbine sound propagation using parabolic equation
This study models the three-dimensional effects of a turbine wake on downstream sound propagation using a parabolic-equation method.
Key idea: Wake-induced flow structures shape how turbine noise propagates in three dimensions, not just along the ground.
Impact of a Two-Dimensional Steep Hill on Wind Turbine Noise Propagation
This paper quantifies how terrain, specifically a steep hill, affects atmospheric propagation of wind-turbine noise.
Key idea: Local terrain features can meaningfully change how far and in what direction wind-turbine noise propagates.
High-performance simulation and open-source tools
Scalable LES and DNS for wind farms and canonical turbulence.
High-fidelity turbulence simulations require scalable numerical methods and efficient use of modern supercomputers. We develop and use simulation tools for wind-farm LES and canonical DNS, including the open-source AFiD framework.
AFiD-GPU: A versatile Navier–Stokes solver for wall-bounded turbulent flows on GPU clusters
AFiD-GPU is a high-performance implementation of the AFiD incompressible Navier-Stokes solver for GPU clusters. It enables large-scale simulations of canonical turbulent flows such as Rayleigh-Bénard convection, Taylor-Couette flow, channel flow, and plane Couette flow.
Key idea: Open, scalable simulation tools are essential for connecting fundamental turbulence physics with high-resolution numerical experiments.
Comparison of computational codes for direct numerical simulations of turbulent Rayleigh-Bénard convection
This paper cross-validates independent direct numerical simulation codes for wall-bounded thermal turbulence, including the AFiD code.
Key idea: Cross-code validation is essential for trusting high-fidelity DNS results across research groups.
Canonical turbulence and thermal convection
Transport, coherent structures, and scaling in controlled turbulent flows.
Canonical turbulent flows provide controlled systems for studying transport, coherent structures, and scaling behavior. These studies support the physical understanding and numerical methods used across our work on wind-energy and environmental flows. See also the thermal convection page.
Turbulent thermal superstructures in Rayleigh-Bénard convection
This study identifies large-scale, long-lived thermal superstructures in turbulent Rayleigh-Bénard convection. It shows that sufficiently large domains are required to capture their organization, while later work demonstrates that domain-size requirements depend on the observable.
Key idea: Turbulent convection contains persistent large-scale organization whose effect on measured statistics depends on the observable and domain size.
How wide must Rayleigh–Bénard cells be to prevent finite aspect ratio effects in turbulent flow?
This paper examines how domain width affects turbulent Rayleigh-Bénard convection. It clarifies when finite-aspect-ratio effects contaminate heat transport and flow organization.
Key idea: Reliable simulations of turbulent convection require domains large enough to contain the relevant large-scale structures.
Scaling relations for heat and momentum transport in sheared Rayleigh-Bénard convection
This study derives how an imposed mean shear changes the classical scaling of heat and momentum transport in convection.
Key idea: Shear changes the balance between heat transport, momentum transport, and coherent turbulent structures.
Related work also covers rotating Rayleigh-Bénard convection and Taylor-Couette turbulence; see those research pages and the publications list for the corresponding papers.
Public-facing results
Accessible examples of the practical consequences of flow physics.
Some results provide especially clear examples of why wind-farm flow physics matters beyond specialist turbulence research.
- Effect of low-level jet height on wind farm performance, and Modeling wind farm noise emission and propagation - also listed above.
Enhanced wind-farm performance using windbreaks
Large-eddy simulations showed that carefully designed low windbreaks can increase power production in large wind farms. The important point is not simply that barriers speed up the flow above them, but that the optimal windbreak for a wind farm is much lower than the optimal windbreak for a single isolated turbine.
Key idea: Small changes to the flow entering a wind farm can have farm-scale consequences for power production.
For the complete chronological list of peer-reviewed articles, see the publications page.