eddy viscosity

Eddy viscosity is a concept in fluid dynamics that describes how turbulent, swirling motion within a fluid increases the mixing and transport of momentum, similar to how viscosity (or "thickness") causes resistance in a smooth, flowing fluid. In turbulent flows, these random, chaotic motions enhance the transfer of momentum, making the fluid act as if it has a higher viscosity. Eddy viscosity is a way to mathematically represent this increased mixing without modeling every tiny swirl, helping engineers predict how fluids behave in complex systems like rivers, weather patterns, or industrial flows.