The planetary boundary layer is the lowermost part of the troposphere which is directly in contact with the surface and houses interesting atmosphere dynamics. The atmospheric flow and turbulence that is accounted for in this layer has tremendous implications for the transport of pollutant, climate change, weather forecast, etc. My work revolves around unraveling the intricate dynamics of this atmospheric layer and their profound implications for meteorological phenomena and climate dynamics. The planetary boundary layer's behavior is significantly influenced by a variety of factors, with the topography of our planet, including mountains and valleys, playing a pivotal role. My primary research objective is to investigate the dynamics of flows over slopes, otherwise known as katabatic flows, and to gain a deeper understanding of their impact on weather forecasting and our comprehension of climate change. To explore these complex atmospheric phenomena, I employ advanced computational techniques, most notably Direct Numerical Simulation. Through these simulations, I aim to contribute to the advancement of our knowledge regarding how topographical features shape the behavior of the planetary boundary layer.