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CFD-post - even/odd timesteps

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Old   June 27, 2022, 18:38
Question CFD-post - even/odd timesteps
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Marta
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Hello!

I've a transient simulation with approx. 35.000 timesteps. I want to generate chart of changing pressure in time in created point but my RAM can't manage.
What I want to get is an expression or function which takes only even or odd timesteps or every third or fourth timestep.

Thanks in advance for any help :)

Best regards,
Marta
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Old   June 27, 2022, 22:29
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Personally I find the charting options in CFD-Post very limiting, if this was me I would send the data to a monitor point. Then it will be available in Solver Manager to chart there or export as a csv file to a more sophisticated graphing package like matlab or python. Then you do not need to fire up CFD-Post at all.

To answer your question - I cannot see any options in CFD-Post to do what you request. But I am not an expert in charting in CFD-Post, have a look around and see what you can do. But next time you run this do as I suggest in the first paragraph and you will not need to use CFD-Post at all to generate these charts.
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Old   June 28, 2022, 15:40
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I don't know if I understand you properly. What I figured out from your reply is setting two expressions as output parameters: 1st - maximum value of pressure in point and 2nd - current time step. In this way I should get a table with maximum values of pressure in designed point in every time step.

In my opinion it should work.
What do you think?
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Old   June 28, 2022, 16:17
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If I understood Glenn correctly, he meant

1 - Create monitor point in CFX-Pre, using coordinates
2 - Select Pressure as the variable to be monitored at the location in (1)
3 - Monitor transient signal in the SOlver Manager as the solution progresses.
4 - Once solution is finished, export (right click on the SolverManager plot) to an external file
5 - Alternatively, create chart in CFD-Post and select Monitor Data in the Data Series tab.

hope the above helps,
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Old   June 30, 2022, 17:30
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Hi Opaque!

Thank you for clarifying me these steps.

I've tried to do what you wrote:
1. I created a point, using coordinates point.png
2. Select Pressure as the variable to be monitored - in this step I'm not sure how to set parameters correctly. Can you help me with it?
3. How to manage 3rd step?

The picture below presents settings of created variable 'pressure' in CFX-Pre.
'Variable Type' allows me to choose one of three options: Specific, Volumetric and Unspecified. I chose first one - Specific but I'm not sure if this is correct.
What do you think about it?
new variable - pressure.png
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Old   June 30, 2022, 19:47
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No, you are looking at the wrong bit. You want a monitor point, which is in the output tab.
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Old   July 3, 2022, 07:27
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Hi there!

Okay - what I've done this time is setting expressions (probe of pressure and WSS in created point) as an outputs parameters.
CFX + Parameter Set.png

What I got is a table with designed points. Apart from these parameters I also added a Current Time Step as an output parameter. Do you think it is necessary?
Parameter Set.png

I hope this is what you meant
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Old   July 3, 2022, 08:49
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Um, no. That is not what I meant. You get the data out using Solver Manager, not as a parameter into Workbench.

Doesn't Opaque's post tell you exactly what to do? If you do not understand Opaque's post why don't you ask about what you do not understand?
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Old   July 3, 2022, 09:06
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Hi Glenn, thank you for your answer. I will follow your advice and ask Opaque some questions.
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Old   July 3, 2022, 09:20
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You ask questions to the forum, not to specific people. So post your question here and we will try to answer it.
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Old   July 3, 2022, 09:25
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Quote:
Originally Posted by Opaque View Post
If I understood Glenn correctly, he meant

1 - Create monitor point in CFX-Pre, using coordinates
2 - Select Pressure as the variable to be monitored at the location in (1)
3 - Monitor transient signal in the SOlver Manager as the solution progresses.
4 - Once solution is finished, export (right click on the SolverManager plot) to an external file
5 - Alternatively, create chart in CFD-Post and select Monitor Data in the Data Series tab.

hope the above helps,
OK, fine. I've never done the path like this before so I have a question to the first step (creating monitor point in CFX-Pre, using coordinates).
Can you tell me how to do it correctly?
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Old   July 5, 2022, 10:33
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To create a monitor point,

1 - In the Outline in CFX-Pre, there is a Output Control item, open it
2 - There is a Monitor Tab
3 - Insert a Monitor Point, check available options, and select what you need.

I think these steps are described in several tutorials, so it should be clear (and perhaps explained better than here) if you do some of them.
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Old   July 6, 2022, 13:39
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Thanks! Now it works!
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