Thermische en ruwheidsheterogeniteiten in een stabiele grenslaag: Experimentele inzichten en lineaire modellering

Secondary motions induced by heterogeneous surface conditions represent an important yet incompletely understood feature of turbulent boundary layers. These motions, which manifest as coherent streamwise-elongated vortices, redistribute momentum, heat, and scalars in the wall-normal and spanwise directions, thereby modulating drag, mixing, and transport in the atmospheric boundary layer (ABL). While prior work has examined mechanically driven secondary motions arising from surface roughness variations, and thermally driven motions arising from buoyancy gradients, the combined influence of roughness and thermal heterogeneity is not tackled in the literature. This gap restricts both physical understanding and the development of predictive models for stratified boundary layers, which are common in geophysical and environmental settings. The current PhD research aims at generating new experimental data sets that extend the current knowledge by studying combined roughness and thermal heterogeneities in 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 hybrid secondary motions, drag, and heat transfer in stable boundary layers. Moreover, results are used to develop new models that allow to better represent thermal influenced secondary motions in numerical simulations codes, such as regional climate models or microscale boundary-layer models.