Richard J.A.M. Stevens

Professor at the University of Twente

Wind energy · Turbulence · Environmental flows

Wind farms and turbulence

At the University of Twente, we study wind-farm–atmosphere interaction and turbulent heat and momentum transport using large-eddy simulation, direct numerical simulation and physical models.

Selected contributions · Simulation videos · Evidence and recognition

Wind-farm–atmosphere interaction

Large-eddy simulations resolve turbine wakes and farm-scale turbulent transport. The ERC WINDFLOW project aims to connect wind-farm flows to changing weather conditions through multiscale modelling.

Wind-farm flow and wakes
Blue low-velocity turbine wakes in a large-eddy simulation of an aligned wind farm.
Blue regions show low-velocity turbine wakes. Visualization by David Bock (XSEDE). · Full-resolution visualization

With J.H. Kasper, we found that wake recovery changes with farm size: spanwise turbulent transport dominates behind a single turbine, while vertical turbulent transport and downward mean-flow transport dominate behind the larger neutral, staggered arrays studied.

With J. Graham and Charles Meneveau, I co-developed concurrent-precursor inflow, which supplies evolving atmospheric turbulence to a finite wind-farm simulation without storing an inflow database.

Atmospheric and turbulent boundary layers

Structure and scaling of the turbulent boundary layer that supplies wind farms with momentum and energy.

Flow visualization showing elongated turbulent structures in a boundary layer.

Related wind-energy aeroacoustics research examines how wakes, turbine layout, terrain and the atmosphere affect sound propagation. See the wind-farm layout and noise study.

Multiscale prediction and physical modelling

Reduced-order models connect turbine-wake dynamics to the atmospheric momentum supply, making predictions across more layouts and conditions than high-fidelity simulation alone can cover.

Physics-based wind-farm modelling

Developed with Dennice Gayme and Charles Meneveau, the coupled wake–boundary-layer (CWBL) model links turbine-wake geometry to an atmospheric-boundary-layer momentum balance. For the neutral regular arrays studied, coupling the two scales improves aggregate power trends.

Plan view of staggered wind turbines and their expanding downstream wakes in the analytical model.

Current work examines atmospheric contributions to wind-farm power spectra and power response to changing wind speed, including atmospheric variability and finite wake-adjustment times.

Turbulence simulation and high-performance computing

Direct numerical simulation isolates heat- and momentum-transport mechanisms in canonical flows and provides controlled cases for numerical methods.

Computational method and software

AFiD and AFiD-GPU

With the international solver team, I co-developed AFiD-GPU for parallel simulations of wall-bounded turbulence. The AFiD solver family supports canonical convection and shear flows; see the GPU methods paper and the repositories for supported configurations.

Visualization by E. van der Poel and R. Ostilla-Mónico. The collaboration includes the University of Twente, University of Rome “Tor Vergata”, SURFsara and NVIDIA.

Canonical systems

Thermal convection

Rayleigh–Bénard convection is a controlled system for studying buoyancy-driven turbulent heat transport.

Taylor-Couette and wall turbulence

Flow between differentially rotating cylinders provides a closed wall-bounded system for studying momentum transport and drag.

Taylor–Couette geometry: concentric cylinders of height L, inner radius r_i and outer radius r_o, rotating at angular velocities omega_i and omega_o.

Thermal-convection subtopics

The Thermal convection visualization gallery preserves the complete flow previews for these topics.

Research collaboration

We welcome collaborations on wind-farm–atmosphere interaction, physical modelling and turbulence simulation. Email Richard Stevens with your research question and proposed approach.

The group is part of the Max Planck–University of Twente Center for Complex Fluid Dynamics. Publications link to available open versions. There is no general public data catalogue, so data availability must be assessed for the specific study.

Evidence and recognition

Funding, journal distinctions, reviewed synthesis, and software availability.

Wind-farm–atmosphere interaction

Contribution

Connecting turbine-wake mechanics to farm-scale momentum supply and atmospheric response, with a synthesis across scales in the Annual Review of Fluid Mechanics.

External evidence

  • European Commission CORDIS records WINDFLOW as an ERC-funded University of Twente project running from May 2024 to April 2029.
  • The Annual Review article synthesizes turbine wakes, wind-farm boundary layers, and atmospheric coupling across scales.

Multiscale prediction and physical modelling

Contribution

Separating turbine-scale losses from farm-scale atmospheric response and testing how physical interventions change those coupled balances.

External evidence

Turbulence simulation and high-performance computing

Contribution

Using canonical direct numerical simulations and scalable solvers to isolate heat- and momentum-transport mechanisms under controlled conditions.

External evidence