# Non dimensional BL thickness

 Register Blogs Members List Search Today's Posts Mark Forums Read

 December 5, 2017, 15:22 Non dimensional BL thickness #1 New Member   Join Date: Dec 2017 Posts: 2 Rep Power: 0 Hi Folks, I am doing some simple CFD work on paper and am trying to non dimensionalise the maximum boundary layer thickness of a turbulent flow travelling over a airfoil (simplified as a flat plate). I've given it a go but I'm not sure if I'm doing it right. I think that to non dimensionlise the BL I can simply do: Normal BL [m] * frictional velocity [m/s] / kinematic viscosity [m^2/s] I would then set the free stream velocity and the fluid density to equal 1 and then calculate the non-dimensional BL thickness using the equation above and I think I'd get the same dimensionless BL thickness as if I used actual flow values (for example the defaults in Fluent of rho = 1.2047 and dynamic viscosity = 1.789e-5) Am I going about this right? Thanks, Fred

 December 5, 2017, 15:57 #2 Senior Member   Filippo Maria Denaro Join Date: Jul 2010 Posts: 3,751 Rep Power: 41 for a turbulent BL you can estimate the non-dimensional thickness as delta(x)/x = C Re_x^(-1/5)

 December 5, 2017, 16:56 #3 New Member   Join Date: Dec 2017 Posts: 2 Rep Power: 0 Thanks for your reply! Thank you for that equation. Out of interest, does the way I've done it worked? (and also making U_freestream and rho = 1)

 December 6, 2017, 02:50 #4 Member   Ravindra Shende Join Date: Feb 2011 Location: Pune, India Posts: 45 Rep Power: 8 In addition to changing the free stream U and rho, you will also have to change the dynamic viscosity. The dynamic viscosity should be such that the Reynolds number is the same in dimensional as well as non-dimensional cases.

 Thread Tools Display Modes Linear Mode

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post Onurozcan ANSYS Meshing & Geometry 0 December 10, 2015 09:19 Josh CFX 13 October 27, 2013 15:38 Anna Tian Main CFD Forum 2 March 4, 2013 11:45 prikeyma CFX 3 February 12, 2013 04:19 famerfamer STAR-CCM+ 3 July 12, 2012 09:47

All times are GMT -4. The time now is 18:03.