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tsh850227 February 12, 2012 19:08

How to check the flowrate in a simulation including transient term
 
I am a new user of CFX, I did a simulation several days ago. It includes a transient term, so the flowrate is changing with time. After the running of the simulation, I do not know how to check the time-averaged flowrate. Anybody can help me?

Sorry for that my English is quite poor.

thanks in advance.

ghorrocks February 13, 2012 07:06

Your English seems plenty good enough to me.

To check the mass flow rate over time you need to have included a monitor point reading the mass flow rate. Then you can load the run in Solver Manager and see the mass flow arate versus time, and export it if you want to do more advanced analysis on it. This approach is the best as it gives you the flow rate with the full time step resolution of the simulation.

If you did not create the monitor point then you can extract the mass flow rate of any time step you wrote a results file for. Usually this is much fewer than the number of timesteps so you will have lost information this way, but it is all you can if you cannot run it again.

If no monitor point and no results files then you are stuffed. The data is lost and the only way to recover it is to rerun with the monitor points defined.

tsh850227 February 13, 2012 07:54

Quote:

Originally Posted by ghorrocks (Post 344115)
Your English seems plenty good enough to me.

To check the mass flow rate over time you need to have included a monitor point reading the mass flow rate. Then you can load the run in Solver Manager and see the mass flow arate versus time, and export it if you want to do more advanced analysis on it. This approach is the best as it gives you the flow rate with the full time step resolution of the simulation.

If you did not create the monitor point then you can extract the mass flow rate of any time step you wrote a results file for. Usually this is much fewer than the number of timesteps so you will have lost information this way, but it is all you can if you cannot run it again.

If no monitor point and no results files then you are stuffed. The data is lost and the only way to recover it is to rerun with the monitor points defined.

Many many thanks
I really appreciated your kind help

The flow is in a pipe, I need to read the flow rate in this whole pipe, if I creat a moniter point and read the velocity(I started simulation with CFX three weeks ago, sorry for that I cannot find the option of mass flow rate in the drop list in moniter point setting up and I do not understand how to operate), then whether I need to integrate the velocity on some plane to get the volume flow rate?

Here is the description about this simulation. Firstly, a steady flow in a pipe was simulated, then the flowrate was recorded. Secondly, sinusoidal vibration is applied on the wall of this pipe, then time averaged flow rate is recorded and will be compared with the previous flow rate of steady flow. I used transient statistics tool in output control tab to read the velocity data and get "trn velocity" in CFX-post, then I used function "areaInt" to integrate "trn velocity" on a cross plane in this pipe, and got the volume rate. Can you help me to check my work? I think the result should be what I want.
looking forward to your reply

Thanks again¬¬
nice day


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