Piiritlemiskihtide

Piiritlemiskihtide, often translated as boundary layers, are thin regions of fluid or gas close to a solid surface where the effects of viscosity are significant. Outside this layer, the fluid flow is largely unaffected by the presence of the surface. The concept of the boundary layer was first introduced by Ludwig Prandtl in 1904.

Within the boundary layer, the fluid velocity transitions from zero at the surface (due to the no-slip condition) to the velocity of the free stream further away. This velocity gradient is responsible for the generation of shear stress at the surface, which leads to drag. The thickness of the boundary layer is generally small, but it plays a crucial role in determining the overall flow behavior, heat transfer, and mass transfer phenomena.

Boundary layers can be either laminar or turbulent. Laminar boundary layers are characterized by smooth, orderly fluid motion, while turbulent boundary layers exhibit chaotic, swirling eddies. The transition from laminar to turbulent flow is a complex process influenced by factors such as flow velocity, surface roughness, and pressure gradients. Understanding and predicting boundary layer behavior is essential in various fields, including aerodynamics, hydrodynamics, and thermal engineering, for designing efficient and safe systems.