The Perdigao campaign 2017 was an international field campaign to measure the flow and its diurnal variation in the atmospheric boundary layer over complex terrain. A huge dataset of meteorological observations was collected over the double-hill site by means of state-of-the-art meteorological measurement techniques. A focus of the campaign was the interaction of the boundary layer flow with a single wind turbine, which was located on the south-western (SW) ridge top. In this study a long-term nested large-eddy-simulation (LES) of 49 days duration with a maximum horizontal resolution of 200 m is used to describe both the general meteorological situation over Spain and Portugal and the local small-scale flow structures over the double-hill during the intensive observation period (IOP). The simulations show that frequently observed nocturnal low-level jets (LLJ) from NE have their origin over the slopes of the elevated plateau between the Portuguese Serra da Estrela and the Spanish Sierra de Gata mountain ranges N and NE of Perdigao and that the diurnal clockwise turning of the wind direction over the double-ridge is induced by slope- and valley-winds under weak synoptic conditions. It is found that in spite of the long simulation time, modelled and observed wind structures on the ridge tops agree well, while along-valley flow within the valley is underestimated by the model.