Singular Perturbations and Boundary Layers

Focusing on singular perturbations in partial differential equations, this monograph explores the impact of small coefficients on high-order derivatives, leading to the formation of boundary layers. These layers, crucial in various physical phenomena, prominently arise in fluid mechanics, such as airflow around planes or vehicles, and in geophysical contexts like the air-ocean interface. The study primarily examines elliptic and parabolic equations within bounded domains, emphasizing their relevance to thermic, fluid mechanics, and optics.