Boundary condition in viscous fluid

Lionel BRS

Hi all,

I read on a website that the boundary condition between a flow and a wall is both no slip condition (fluid and wall at the same velocity) and null pressure gradient.

I dont really understand the reason of the null pressure gradient. As the velocity gradient can be high in a boundary layer, I would believe that there could be a pressure gradient too.

Could someone tell me about the physical reason ?

By the way, here is the page which says that the pressure gradient is null (see "Viscous wall") http://www.grc.nasa.gov/WWW/winddocs...c.html#bc:wall