Near Wall Question
 

hi all
why does the region very close to walls need special treatment in modelling tubulent flows?
Cheers

not just in turbulent flows, in all flow regimes the boundary layer has to be resolved as accurate as possible, it just happens that all gradients are very severe and accurate resolution is very very expensive albeit few academic cases.

I suggest you to read an introductory chapter about Boundary Layer theory, Anderson's book, Fundamentals of Aerodynamics, has a good introduction.

For a classical work in the field see "Boundary Layer Theory" by H. Schlichting.

Do

A simple intriduction to these things can be found here
http://www.fluent.com/software/unive.../turbulent.pdf

Enjoy!

it's one of the most important effects in fluid movement.