Evaluation of utau
 

Hi,

I am simulating turbulent duct flow and wish to calculate Utau.

If I have a cell in the viscous sublayer I can use Newtons law to get Utau.

If I do not have a cell in the viscous sublayer I can use Newton - Raphson and the log-law assumption to obtain a Utau value.

The problem is if one method gives a utau value indicating that the first cell is in the viscous sublayer and the other puts the cell outside the viscous sublayer which do I use ????

I have heard of a method using the local reynolds number - ie if Re_local < magic number then use Newtons law...

does anyone have any ideas?

Thanks in advance

Tim.

Re: Evaluation of utau - problem solved
 

I mangaged to solve the problem

Thanks anyway

Tim.