Introduction to Boundary Layer Theory : Fluid Mechanics (mechanical engineering)

If the movement of fluid is not affected by its viscosity, it could be treated as the flow of ideal fluid and the viscosity term could be omitted. Therefore, its analysis would be easier. The flow around a solid, however, cannot be treated in such a manner because of viscous friction. Nevertheless, only the very thin region near the wall is affected by this friction. Ludwig Prandtl identified this phenomenon and had the idea to divide the flow into two regions. They are: 1. the region near the wall where the movement of flow is controlled by the frictional resistance; and 2. the other region outside the above not affected by the friction and, therefore, assumed to be ideal fluid flow. The former is called the boundary layer and the latter the main flow