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-   -   STAR CCM+ need help！ (https://www.cfd-online.com/Forums/star-ccm/242286-star-ccm-need-help.html)

Roxine April 13, 2022 09:27
STAR CCM+ need help！
 
I have two questions.

1. I am used to using the maximum number of steps as the stop standard. Is there a way to set the time as the stop standard?

2. When using the maximum number of steps as the stop standard, I set the X-axis of the monitoring drawing curve to physical time, but why is there no change in the monitoring drawing at runtime? A curve appears when you set the X-axis to the number of running steps.

LuckyTran April 13, 2022 14:03
1. Go to stopping criteria and change it to physical time
2. I don't know what you're doing wrong but it has nothing to do with stopping criteria. I've made plots with physical time on the x-axis. Maybe check out a tutorial or something.

Roxine April 14, 2022 00:51
Hi, I went to the tutorial and found this sentence:

If you are running steady state solver, but want to use physical time for drawing, run the unsteady state solver first, then switch to the steady state solver. This ensures that there is a "physical time" in the simulation.

I'm doing steady state analysis, but I don't understand exactly what to do with this sentence.

Roxine April 14, 2022 00:52
Quote:
Originally Posted by LuckyTran (Post 826208)
1. Go to stopping criteria and change it to physical time
2. I don't know what you're doing wrong but it has nothing to do with stopping criteria. I've made plots with physical time on the x-axis. Maybe check out a tutorial or something.
Hi, I went to the tutorial and found this sentence:
If you are running steady state solver, but want to use physical time for drawing, run the unsteady state solver first, then switch to the steady state solver. This ensures that there is a "physical time" in the simulation.
I'm doing steady state analysis, but I don't understand exactly what to do with this sentence.

FliegenderZirkus April 14, 2022 04:49
There is no physical time in a steady simulation so you cannot have time on the x axis of your monitor plots, only iteration number.
Quote:
Is there a way to set the time as the stop standard?
Perhaps you mean the "wallclock" time here? Say, you start the simulation at 9 AM and want it to stop at 5 PM, that is after 8 hours wallclock time, no matter what how far the simulaiton got. In this case you'd need a Monitor stopping criterion based on the Total solver elapsed time report, It's a little bit more involved but perfectly doable.

LuckyTran April 14, 2022 07:16
If you are running a steady state simulation, why are we even talking about physical time?

Roxine April 14, 2022 10:27
Quote:
Originally Posted by LuckyTran (Post 826249)
If you are running a steady state simulation, why are we even talking about physical time?
Thank you. Thank you very much. I understand now.
Thank you very much for answering my questions many times. Wish you a happy life!

Roxine April 14, 2022 10:31
Quote:
Originally Posted by FliegenderZirkus (Post 826241)
There is no physical time in a steady simulation so you cannot have time on the x axis of your monitor plots, only iteration number.

Perhaps you mean the "wallclock" time here? Say, you start the simulation at 9 AM and want it to stop at 5 PM, that is after 8 hours wallclock time, no matter what how far the simulaiton got. In this case you'd need a Monitor stopping criterion based on the Total solver elapsed time report, It's a little bit more involved but perfectly doable.
Thank you. Since I am a beginner, I am not familiar with the point that steady-state analysis cannot use physical time as the X-axis. I think that setting the solution as unsteady state will solve my problem. I will communicate with the teacher tomorrow.


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