Calculation of the turbulent kinetic energy

Razielka · March 18, 2016, 04:02

When computing the turbulent kinetic energy (and other related quantities) should I include the velocities on the boundaries when Navier slip boundary condition is applied?

Navier boundary condition:

Us = ls (dUs/dy)wall

Us is the slip velocity, ls - the slip length (parameter), and (dUs/dy)wall is the velocity gradient at the wall.

Also how should I do it if my mesh is non-uniform in one direction?

davidwilcox · March 21, 2016, 00:11

tke applies only to the fluid.

Razielka · March 22, 2016, 01:22

Yes, but under slip condition isn't the velocity of the fluid at the boundary different than the velocity of the wall? My question is in that case shouldn't it be included in the calculation of the turbulent kinetic energy?

And also I'm bit at a loss when it comes to the mathematical expression of the turbulent kinetic energy in the code itself as the mesh is non-uniform and all the other velocities are calculated in the cell centers. Only the velocities at the boundaries are calculated on the cell faces.

March 18, 2016, 04:02	Calculation of the turbulent kinetic energy	#1
Razielka New Member Petya Stoyanova Join Date: Jul 2015 Posts: 4 Rep Power: 10	When computing the turbulent kinetic energy (and other related quantities) should I include the velocities on the boundaries when Navier slip boundary condition is applied? Navier boundary condition: Us = ls (dUs/dy)wall Us is the slip velocity, ls - the slip length (parameter), and (dUs/dy)wall is the velocity gradient at the wall. Also how should I do it if my mesh is non-uniform in one direction?

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March 21, 2016, 00:11		#2
davidwilcox Senior Member david Join Date: Oct 2012 Posts: 142 Rep Power: 13	tke applies only to the fluid.

March 22, 2016, 01:22		#3
Razielka New Member Petya Stoyanova Join Date: Jul 2015 Posts: 4 Rep Power: 10	Yes, but under slip condition isn't the velocity of the fluid at the boundary different than the velocity of the wall? My question is in that case shouldn't it be included in the calculation of the turbulent kinetic energy? And also I'm bit at a loss when it comes to the mathematical expression of the turbulent kinetic energy in the code itself as the mesh is non-uniform and all the other velocities are calculated in the cell centers. Only the velocities at the boundaries are calculated on the cell faces.