Journal of Fluid Mechanics

Boundary conditions at a naturally permeable wall

Gordon S.  Beavers a1 and Daniel D.  Joseph a1
a1 Department of Aeronautics and Engineering Mechanics, University of Minnesota, Minneapolis, Minnesota

Article author query
beavers gs   [Google Scholar] 
joseph dd   [Google Scholar] 


Experiments giving the mass efflux of a Poiseuille flow over a naturally permeable block are reported. The efflux is greatly enhanced over the value it would have if the block were impermeable, indicating the presence of a boundary layer in the block. The velocity presumably changes across this layer from its (statistically average) Darcy value to some slip value immediately outside the permeable block. A simple theory based on replacing the effect of the boundary layer with a slip velocity proportional to the exterior velocity gradient is proposed and shown to be in reasonable agreement with experimental results.

(Published Online March 28 2006)
(Received February 21 1967)