Pulse loss thickness

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

The pulse loss thickness is defined as:

${\displaystyle \theta =(\delta _{2})=\int _{0}^{\delta (\infty )}{\frac {\overline {u}}{u_{0}}}\cdot \left(1-{\frac {\overline {u}}{u_{0}}}\right)\cdot dy}$

With

• ${\displaystyle \delta }$: Thickness of the boundary layer
• ${\displaystyle {\overline {u}}}$: averaged speed curve
• ${\displaystyle u_{0}}$: Inflow velocity of the infinite outer flow.

The shape parameter H of a boundary layer can be determined as the ratio of the momentum loss thickness and the displacement thickness : ${\displaystyle \delta ^{*}}$

${\displaystyle H={\frac {\delta ^{*}}{\theta }}}$

literature

• Dominik Surek , Silke Stempin: Applied Fluid Mechanics , Vieweg + Teubner Verlag 2007, ISBN 3-8351-0118-8 , p. 246

See also

• Boundary layer equations