Influence of pressure gradient on the wake evolution of aligned wind turbines: A large-eddy simulation study

Numerous wind farms have been built on complex terrain. Complex terrain will induce non-zero pressure gradients and thus affect the evolution of wind-turbine wakes. Previous studies mainly focused on the effect of pressure gradient on the wake evolution of a single wind turbine. However, it is not clear how the pressure gradient affects the wake evolution of a row of wind turbines. Therefore, we utilize large-eddy simulation coupled with wall-modelled immersed boundary method to simulate different pressure gradients and investigate their influence on the wake evolution of aligned wind turbines. Results show that the pressure gradient will significantly affect the velocity deficit, wake recovery rate, and wake width of the wake of aligned wind turbines. Compared with the zero-pressure gradient condition, the wake of aligned wind turbines has the smallest velocity deficit and the fastest recovery rate in the favorable pressure gradient (FPG) condition, while the velocity deficit is the largest and the recovery rate is the slowest in the adverse pressure gradient (APG) condition. At the same location downstream of aligned wind turbines, the wake width for the FPG condition is the smallest, and the wake width for the APG condition is the largest.