This research project addresses the analysis of kinetic equations, such as the Boltzmann and Landau equations, which bridge the multiscale gap between microscopic particle systems and macroscopic fluid dynamics. While the theory for these equations in periodic settings is well-developed, the study of solutions in bounded domains remains largely unexplored. The central difficulty lies in the complex interaction between the gas and the physical boundary, particularly at the grazing set, where velocities are tangent to the boundary. The grazing set is a region of criticality where solutions typically exhibit a more singular behavior and new mathematical tools need to be developed in order to study the precise asymptotics of solutions.