The solution I am trying to get is the buoyant flow with 90 degree deflection. I chose k-e turbulence model for this. Someone told me to choose 'SST' model instead, while, according to CFX manual, I think that 'SSG' model might be suitable than 'SST'. Do anyone have any idea?

Anyway, I have the problem with 'y plus' in CFX-Post. I read from some book that y plus is the important parameter to determine if your grid system is OK. However I am not sure which position along the flow path should I use to get y plus, at the inlet? or at the outlet? or at any position that we're sure it is fully developed.

I create the line perpendicular to the wall at many points along the flow path, and then set them to display in variable mode. Y plus is the chosen variable. I don't understand the results. At all points, y plus are constant along the line and aren't defined in the far wall region. Do anyone have any idea for this?

Y plus is the distance of the first node away from the wall,so it must be constant for a perticular wall.

It is the criterion to check your mesh quality. Every turbulance model solves wall functions,as described in helps and uses Y+ to solve,so it is important to have its values within limits for the model.

Try to plot a contour plot for Y+ at your walls. That would give you an idea about your Y+ , and not a line through your domain.Looks like you have no idea about what Y+, try to read through the posts here, they are plenty of them and and they are very helpful.

[manpreet]

Hi guys,
I am working on project Flow analysis through Rotor 37. I have done meshing in turbogrid by following tutorials. Could anyone let me know how to calculate Y plus or how to plot values of Y plus at the wall in CFD post. What should I read for this any book or tutorials??
Thanks
Manpreet Singh
manpreet_singh_er@yahoo.co.in

[brunoc]

The CFX documentation has lots of tutorials that show how to calculate variables and plot them on charts. Take a look at them. Seriously.
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To see the the values of a variable on the wall, just enable the wall and color it by such variable. For charts, you'll need to create a line over the wall. This can be done by creating a polyline of the intersection between a plane and a wall. Take a look at the tutorials.

[manpreet]

Thanks Brunoc,
Could you please lt me know specific tutorial to follow for plotting y plus and also plz let me now which turbulence model do I need to use for my model .My model is NASA rotor 37 having transonic flow in it and I am working with CFX solver, do u know how solver solve variables I mean its along nodes on boundaries of control volume or at center. Kindly consider my request. I really appreciate help being provided by you.
Thanks

[ghorrocks]

Have a look at the contents of the tutorials to determine which is best. Even better, do them all.

Control volumes - this is all discussed in the CFX documentation theory manual.

If you have no idea about turbulence models then use the SST model. Only consider a different model if you have good reason to do so.