CFD Online Discussion Forums

CFD Online Discussion Forums (
-   CFX (
-   -   Some help with the results, please (

zona February 5, 2010 16:53

Some help with the results, please
1 Attachment(s)
Hi, I've been working on a CFD simulation on a pumps for some time now, but I have some doubts about the results I'm getting from it.
This is my process of calculation
1. make 3D model is SolidWorks
2. create the mesh in ANSYS
3. make a simulation boundary conditions ShearStress, MassFlow in, Static Preasure outlet (I put hier 0bar is this OK or shoul I put normal preasure???), and I use frozen rotor
4.finally after the calculations I use turbo macro Liquid Pump Performance to calculate the head and efficiency, (I get strange result for the efficiency anny ideas why????)
5. I repeat the calculations for 5-6 different flows and get head and efficiency and make Q-H and Q-eta diagrams in EXCEL
is this a good way to works
is there an automated way to calculate more than one point at once and to get an automated Q-H diagram...
- what is better for pumps Shear Stress or K-epsilon (turbulence model)
what is reference radius and reference height in the Liquid Pump Performance calculation (I change them but nothing happends!)

ghorrocks February 7, 2010 17:25

Unless you know what the wall shear stress is then do not use it. Almost always you don't know the wall shear stress so let the turbulence model calculate it for you. Also consider the SST turbulence model over the k-e model. It is better in just about all respects.

Yes, you can automate your curve generation. Have a look in the workbench tutorials about how to get WB to do this.

As for if your method is good - the devil is in the detail. But if you have not done a mesh and convergence sensitivity study and checked your boundaries are appropriate and the physics models are good then you are just guessing.

zona February 8, 2010 04:01

Hi thanks for the tips, can You, please be a little bit more specific about this

Originally Posted by ghorrocks (Post 245275)
Yes, you can automate your curve generation. Have a look in the workbench tutorials about how to get WB to do this.

I was searchif the PDF files but with no luck

ccs_2v June 6, 2013 01:28

Hi I am facing the same problem
Hi I am facing problems in getting Efficiency Values which make sense for a pump.
I am new to CFX ,Did you find any Solution, i have browsed thru the forum but cant make a clear direction, if the above was solved can you share the solution to get proper efficiency in CFX.
Thank for Help in advance.

All times are GMT -4. The time now is 09:18.