Boundary-layer thickness#Momentum thickness

The impulse loss thickness, a term used in fluid mechanics ( boundary layer theory, ) is a measure of the reduction of the pulse current in the boundary layer due to the influence of friction.

Use the momentum thickness and displacement thickness can be determined as the ratio of the shape parameter H of a boundary layer:

The momentum thickness is defined as:

: Thickness of the boundary layer: averaged velocity profile: Inflow velocity of the infinite outer flow