Plotting boundary layer thickness along x coordinate, general thoughts

mix · June 5, 2013, 14:05

Hey everyone,

currently, I'm working on my masters thesis. I do now have a problem, which is related to boundary layer growth on a flat plate.
I would like to plot the boundary layer thickness calculated by the code along the streamwise coordinate to compare boundary conditions in order to simulate bl suction (see the image attatched).
There are formulae to calculate the thickness of a turbulent bl on a flat plate, but the single variable given in these equations is the x coordinate infuencing the coordinate based reynolds number. as I will have a suction patch somewhere "down the road", which will influnce bl growth and thickness, this method is unrewarding yet not ... the actual bl calculated by the cfd code.
I hope you guys do have some ideas on that topic as I am going nuts not finding a proper solution.

Greetings

mettler · June 5, 2013, 15:50

just out of curiosity, what velocity are you using for the local Re at your suction?

mix · June 5, 2013, 16:53

The suction volocity in negative y direction ist 0.1*freestream velocity, if you mean this. This is a value taken from literature.

Aeronautics El. K. · June 8, 2013, 17:01

Hi Michael.

May I ask why you made this schematic the way you did? I mean, it looks as if there is a flow before the suction patch - a flow that's totally sucked by the patch - and another flow just after it. Will the suction patch be big or powerful enough so as to suck the whole flow in that region?

mix · June 9, 2013, 10:15

No the bl won't be sucked in completely. The schematic was a quick drawing with powerpoint to show what I want to plot: The reduction of bl thickness by the suction. There will be a constant flow over the patch.

June 5, 2013, 14:05	Plotting boundary layer thickness along x coordinate, general thoughts	#1
mix New Member Michael Join Date: Dec 2012 Location: Karlsruhe, Germany Posts: 16 Rep Power: 13	Hey everyone, currently, I'm working on my masters thesis. I do now have a problem, which is related to boundary layer growth on a flat plate. I would like to plot the boundary layer thickness calculated by the code along the streamwise coordinate to compare boundary conditions in order to simulate bl suction (see the image attatched). There are formulae to calculate the thickness of a turbulent bl on a flat plate, but the single variable given in these equations is the x coordinate infuencing the coordinate based reynolds number. as I will have a suction patch somewhere "down the road", which will influnce bl growth and thickness, this method is unrewarding yet not ... the actual bl calculated by the cfd code. I hope you guys do have some ideas on that topic as I am going nuts not finding a proper solution. Greetings Last edited by mix; June 5, 2013 at 16:54.

June 8, 2013, 17:01		#4
Aeronautics El. K. Senior Member Lefteris Join Date: Oct 2011 Location: UK Posts: 337 Rep Power: 15	Hi Michael. May I ask why you made this schematic the way you did? I mean, it looks as if there is a flow before the suction patch - a flow that's totally sucked by the patch - and another flow just after it. Will the suction patch be big or powerful enough so as to suck the whole flow in that region? __________________ Lefteris

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June 5, 2013, 15:50		#2
mettler Senior Member Andrew Join Date: Mar 2009 Location: Washington, DC Posts: 209 Rep Power: 18	just out of curiosity, what velocity are you using for the local Re at your suction?

June 5, 2013, 16:53		#3
mix New Member Michael Join Date: Dec 2012 Location: Karlsruhe, Germany Posts: 16 Rep Power: 13	The suction volocity in negative y direction ist 0.1*freestream velocity, if you mean this. This is a value taken from literature.

June 9, 2013, 10:15		#5
mix New Member Michael Join Date: Dec 2012 Location: Karlsruhe, Germany Posts: 16 Rep Power: 13	No the bl won't be sucked in completely. The schematic was a quick drawing with powerpoint to show what I want to plot: The reduction of bl thickness by the suction. There will be a constant flow over the patch.