Windtunnelexperimenten van multischaaltopografie in turbulente grenslagen

The atmospheric boundary layer (ABL) is governed by the interaction of the wind system with surface topography. Very often, topography has a multiscale structure, with scales ranging from hundreds of meters down to submillimeter level. The representation of multiscale roughness in simulations remains a major challenge, limiting predictive capabilities in application areas such as wind energy, pollutant dispersion, etc. In recent years, it was found that roughness elements can lead to secondary motions that extend into the outer layer of the boundary layer, resulting in significant horizontal inhomogeneity. The current PhD research aims at generating new experimental data sets that extend the current knowledge of multiscale roughness towards stable boundary layers, which are prevalent in the atmosphere. To this end, dedicated wind tunnel experiments are set-up at Portland State University that will investigate the effect of multiscale topography on secondary motions, drag, and heat transfer in stable boundary layers. Moreover, results are used to develop new models that allow to better represent multiscale roughness in numerical simulations codes, such as regional climate models or microscale boundary-layer models.