hi all what does mean non equilibrium boundary layer. thanks

Hi,

this refers to the ballance of production of turbulent kinetic energy and the dissipation. When the 2 are in a rough ballance the turbulent boundary layer is said to be in equilibrium.

This has important consequences in turbulence modelling. We can fairly easily write the production terms and have some confidence in how close the modeling is to the true physics.

We always have trouble coming up with arguments for the dissipation terms and infact most models that use a dissipation equation have so many assumptions imbedded along the way that you really have to view it as a model equation.

A good place to start reading is the chapter on turbulence in Ferziger and Peric's text.

Best Regards,

Bak_Flow

thanks Bak_Flow abdellah