Modelling wind farms in non-neutral atmospheric boundary layer using Lattice Boltzmann methods

Analytical wind farm flow models are used for the optimisation and design of wind farms due to their low computational cost. However, with constantly increasing rotor sizes, their interaction with the atmospheric boundary layer (ABL) increases, and high-fidelity simulations are needed to understand the ongoing flow physics and set up new analytical wake models. Typically, traditional Navier-Stokes-based solvers are too slow and do not allow the generation of the necessary simulation database to set up the analytical models. 
An alternative is the Lattice Boltzmann method (LBM), for which we use the waLBerla-wind solver. LBM is very efficient, especially on GPUs. Preliminary work allowed accounting for wind turbines using actuator lines and/or disks in the solver. A dedicated wall law also allows the modelling of idealised neutral atmospheric boundary layers. This thesis aims to model atmospheric stability (turbulent heat transfers within the ABL) and complex terrain phenomena. 
Atmospheric stability has a major impact: under stable conditions (negative heat flux at the ground), turbulence is damped, and wakes do not meander. They propagate very far downstream. Large eddies are emerging under unstable conditions (positive turbulent heat flux at the ground) and lead to strong wake meandering. Thus, they quickly dissipate. Furthermore, under stable atmospheric conditions, the ABL height is relatively low, inducing a blockage effect around wind farms, strongly impacting their performances. Gravity waves may also appear. Complex terrain allows for modelling the shore’s impact on the wind farm flow. The presence of the shore may, for example, induce wind gusts, heterogeneous inflows, or other important phenomena.

Keywords: Wind energy, wind farms, atmospheric boundary layers, Lattice - Boltzmann methods.

• Academic supervisor    Pr. Simon MARIÉ, CNAM, simon.marie@lecnam.net, ORCID : 0000-0002-4965-9987
• Doctoral School    ED432 SMI, Université HESAM
• IFPEN supervisor    Dr. Frédéric BLONDEL, frederic.blondel@ifpen.fr, ORCID : 0000-0002-3252-2781
• PhD location    IFPEN, Rueil-Malmaison, France 
• Duration and start date    3 years, starting in the fourth quarter 2025 (November, 3rd 2025)
• Employer    IFPEN
• Academic requirements    University Master degree in Fluid Mechanics
• Language requirements    English level B2 (CEFR)    

To apply, please send your cover letter and CV to the supervisors indicated here below.