Viscous Sublayer thickness

sihaqqi · January 1, 2015, 02:05

Hi

Can anyone advise me how to determine viscous sublayer region thickness in my geometry. I am doing Fluid structure interaction for air flowing in pipes. Normally it is assumed if structural displacements are less than viscous sublayer region thickness, one way FSI is alright. I have used OpenFOAM to model LES with PISOFOAM. Kindly advise if there is any method in OpenFOAM or manual calculation that I can use.

Also, please advise if it is possible to determine viscous sublayer region thickness along the whole length of the geometry i.e., if my pipe is 5m long, I would like to have displacements at each meter.

Regards
Imad Haqqi

ssss · January 1, 2015, 14:34

Get your y+ using yPlus, go to paraview and see how far is your first cell from the boundary, with that you can obtain the relationship between the yPlus and y, so you only need to multiply the y * 5 to get your viscous sublayer if I remember correctly

sihaqqi · January 1, 2015, 17:16

Many thanks for sparing time to answer this question. I used yplus calculator to calculate first cell distance from the wall. So this means I only need to multiply that cell distance with 5. Correct?

Regards

January 1, 2015, 02:05	Viscous Sublayer thickness	#1
sihaqqi Senior Member starter Join Date: Sep 2012 Posts: 125 Rep Power: 15	Hi Can anyone advise me how to determine viscous sublayer region thickness in my geometry. I am doing Fluid structure interaction for air flowing in pipes. Normally it is assumed if structural displacements are less than viscous sublayer region thickness, one way FSI is alright. I have used OpenFOAM to model LES with PISOFOAM. Kindly advise if there is any method in OpenFOAM or manual calculation that I can use. Also, please advise if it is possible to determine viscous sublayer region thickness along the whole length of the geometry i.e., if my pipe is 5m long, I would like to have displacements at each meter. Regards Imad Haqqi Last edited by sihaqqi; January 1, 2015 at 02:08. Reason: better structure

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January 1, 2015, 14:34		#2
ssss Senior Member anonymous Join Date: Aug 2014 Posts: 205 Rep Power: 12	Get your y+ using yPlus, go to paraview and see how far is your first cell from the boundary, with that you can obtain the relationship between the yPlus and y, so you only need to multiply the y * 5 to get your viscous sublayer if I remember correctly

January 1, 2015, 17:16		#3
sihaqqi Senior Member starter Join Date: Sep 2012 Posts: 125 Rep Power: 15	Many thanks for sparing time to answer this question. I used yplus calculator to calculate first cell distance from the wall. So this means I only need to multiply that cell distance with 5. Correct? Regards