Reynolds number basis

CFDstudent · April 26, 2009, 19:55

How do I convert a Reynolds number based on momentum thickness (Re theta) to a Reynolds number based on boundary layer thickness (Re delta) ?

This is for turbulent flow in a pipe over a rough boundary.

any help would be greatly appreciated.

thanks!!!

vishyaroon · April 27, 2009, 13:41

In general the momentum thickness (for turbulent flows in pipe/channels) is about 7/72* BL thickness. So you can also use this ratio to compute your new Re.

You may also want to check if the following web-page is helpful.

http://www.see.ed.ac.uk/~bille/teach...Layers9&10.ppt

April 26, 2009, 19:55	Reynolds number basis	#1
CFDstudent New Member Join Date: Apr 2009 Posts: 6 Rep Power: 17	How do I convert a Reynolds number based on momentum thickness (Re theta) to a Reynolds number based on boundary layer thickness (Re delta) ? This is for turbulent flow in a pipe over a rough boundary. any help would be greatly appreciated. thanks!!!

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April 27, 2009, 13:41		#2
vishyaroon Senior Member Aroon Join Date: Apr 2009 Location: Racine WI Posts: 148 Rep Power: 17	In general the momentum thickness (for turbulent flows in pipe/channels) is about 7/72* BL thickness. So you can also use this ratio to compute your new Re. You may also want to check if the following web-page is helpful. http://www.see.ed.ac.uk/~bille/teach...Layers9&10.ppt