A concurrent precursor inflow method for Large Eddy Simulations and applications to finite length wind farms

• We use Large Eddy Simulations to model finite length wind-farms.
• The inflow conditions are obtained using a novel concurrent precursor method.
• The time-evolving streaky structures of the atmospheric boundary layer are captured.
• This method prevents the usage of large databases to store inflow conditions.
• This limits I/O operations, which is beneficial from a computational point of view.

In order to enable simulations of developing wind turbine array boundary layers with highly realistic inflow conditions a concurrent precursor method for Large Eddy Simulations is proposed. In this method we consider two domains simultaneously, i.e. in one domain a turbulent Atmospheric Boundary Layer (ABL) without wind turbines is simulated in order to generate the turbulent inflow conditions for a second domain in which the wind turbines are placed. The benefit of this approach is that a) it avoids the need for large databases in which the turbulent inflow conditions are stored and the correspondingly slow I/O operations and b) we are sure that the simulations are not negatively affected by statically swept fixed inflow fields or synthetic fields lacking the proper ABL coherent structures. Sample applications are presented, in which, in agreement with field data a strong decrease of the power output of downstream wind-turbines with respect to the first row of wind-turbines is observed for perfectly aligned inflow.