[mattyg101]

Hi all,

I have set up a 2D, axisymmetric impinging jet domain similar to that used by Cooper et al (1993) and Craft et al (1993). My aim is to obtain some RANS data for comparison purposes.

I have defined the boundary conditions as follows:



I have run the simulation using k-e (standard model using non-equilibrium wall functions) and Re stress (quadratic pressure-strain model with non-equilibrium wall functions)

In the radial wall jet the turbulent kinetic energy and Re stresses respectively do not go to zero. In the case of the Re stress model, they show a sharp positive spike at the wall. I think this is a problem with the boundary conditions i am using at the wall dont have enough Fluent experience.

Is anyone familiar with this problem or could possibly shead some light on my problem? I would be very grateful.

Matt

[Ali.nabavi]

Originally Posted by mattyg101

Hi all,

I have set up a 2D, axisymmetric impinging jet domain similar to that used by Cooper et al (1993) and Craft et al (1993). My aim is to obtain some RANS data for comparison purposes.

I have defined the boundary conditions as follows:



I have run the simulation using k-e (standard model using non-equilibrium wall functions) and Re stress (quadratic pressure-strain model with non-equilibrium wall functions)

In the radial wall jet the turbulent kinetic energy and Re stresses respectively do not go to zero. In the case of the Re stress model, they show a sharp positive spike at the wall. I think this is a problem with the boundary conditions i am using at the wall dont have enough Fluent experience.

Is anyone familiar with this problem or could possibly shead some light on my problem? I would be very grateful.

Matt

Hi Matt
Hope ur problem was solved as it was for a long time ago ...
I'm gonna model the impinging jet via fluent and regarding mr cooper data , but I have some problem.
One is about the wall boundary condition which I consider constant flux but I don't know the value another thing is how did you define for ur inlet profile.

[meangreen]

I did this a long time ago, and then posted my results on this very forum. Let me see if I can find the link.

[meangreen]

here we go, the pdf's are linked towards the bottom of the post.

http://www.cfd-online.com/Forums/mai...different.html

[Ali.nabavi]

Originally Posted by meangreen

here we go, the pdf's are linked towards the bottom of the post.

http://www.cfd-online.com/Forums/mai...different.html

thanx , but my problem is not the difference between the turbulence model my problem is setupping and optimum case for impinging jet.

tanx so much for your help

[meangreen]

I just followed the same simulation guidelines used for the craft paper. You will need to do sensitivity simulations to check the length of the bottom wall and the pipe development to make sure it isn't affecting your solution. Also, you need to look at the mesh size near the bottom wall to be sure your y+ values are in the correct range.

[mattyg101]

Originally Posted by meangreen

here we go, the pdf's are linked towards the bottom of the post.

http://www.cfd-online.com/Forums/mai...different.html

Better late than never: Thank you for the response and i will read those chapters. They might clarify a few things.

I solved/minimised) my boundary problem by using scalable wall functions for the quadratic RSM.

[birsenakin]

Originally Posted by Ali.nabavi

Hi Matt
Hope ur problem was solved as it was for a long time ago ...
I'm gonna model the impinging jet via fluent and regarding mr cooper data , but I have some problem.
One is about the wall boundary condition which I consider constant flux but I don't know the value another thing is how did you define for ur inlet profile.

how did you draw? I use starcc+. I started to study impinging jet for Re=23000 and H/D=2 but I coudnt do it.? I gave it boundry region for inlet ( D) outlate (sidewall) and wall (top) for gaz .Also, I got mesh but how can I give pressure , velocity and temperature. I coudnt get Nu , wall sheere diagram and simulation. I am new for this. I searched and read all document but I didnt undersant.