Direction of a Neumann BC
 

Hi,

i know that e.g. a Neumann BC for the pressure at a patch is defined as dp/dn where n is the normal to the wall.
My question is, in which direction points this normal vector?
Always in or out of the domain? Or how is it defined?

thanks a lot

I think if you read Jasak's thesis page 94-95 this will be clarified for you.

thanks steven,

so it points always outwards.