How to monitor each node on surface separately?

ApoaJonnz · May 19, 2017, 06:38

Hi,

I'm doing a transient simulation of a periodic flow and need to make sure, that there is no region on a surface, that experiences a Wall-Shear-Stress below a certain margin over the whole period. That means, that it is OK, if it has 0Pa WSS for e.g. 90% of the period, as long as it goes over the threshold for the other 10%.

Thus, I am now looking for a way to monitor the WSS over the period for each node on the surface. Is it somehow possible to get e.g. an output-file that contains the timesteps in the first column and then the WSS for nodes 1 to N of a selected surface in columns 2 to (N+1)?

I would really appreciate any help!

Thanks in advance,
Jonas

LuckyTran · May 20, 2017, 10:40

The built-in feature is only available in v18 and onwards.

in v17 and before, you can write stuff vs time for a single monitor or write all the data at as many locations as you want, but at one time only.

If you are super-skilled however, it is possible to just hack Fluent and force it to write a text file containing the result through a UDF or scheme file. This approach is not really a solution because you could always write a bunch of individual monitor files and read them using another code not in Fluent.

ApoaJonnz · May 22, 2017, 10:51

Thanks for the note regarding V18. I might try that, as we actually should have access to it.
I also might try to write the data for all nodes in one file for certain timesteps. I didn't know, that's actually possible. Do you have a quick guide how to set up a monitor such that it writes out the values for all nodes on a surface for e.g. every10th timestep?

Thanks for the help!

LuckyTran · May 22, 2017, 13:30

In the GUI go to file=>solution data=> automatic export

In the TUI or using a journal file you can write something like...

/file/transient-export ascii "filename" surface1 surface2 () temperature pressure x-velocity y-velocity z-veloicty () no yes another-name 20 time-step

This writes data in ascii format into a file called filename on surface1 and surface2, it writes temperature, pressure, velocities, etc. You should try these text commands in an interactive session to understand what each one does.

Note that in Fluent v17 and onwards, I'm not sure if it's a visual bug or intentional but user created surfaces do not show up in the GUI in the transient export menu. In v16 and before, user created surfaces did show up in this list. Iin v17 & v18 you cannot for example define a plane slice and export transient data on that plane in the GUI (because you cannot select the surface, they simply aren't in the list of surfaces). However, you can still do it using text commands.

ApoaJonnz · May 22, 2017, 15:21

Thank you so much for the quick reply!
I'll try that and hope that the amount of data is not too overwhelming...

May 19, 2017, 06:38	How to monitor each node on surface separately?	#1
ApoaJonnz New Member Jonas Join Date: Apr 2017 Posts: 5 Rep Power: 8	Hi, I'm doing a transient simulation of a periodic flow and need to make sure, that there is no region on a surface, that experiences a Wall-Shear-Stress below a certain margin over the whole period. That means, that it is OK, if it has 0Pa WSS for e.g. 90% of the period, as long as it goes over the threshold for the other 10%. Thus, I am now looking for a way to monitor the WSS over the period for each node on the surface. Is it somehow possible to get e.g. an output-file that contains the timesteps in the first column and then the WSS for nodes 1 to N of a selected surface in columns 2 to (N+1)? I would really appreciate any help! Thanks in advance, Jonas Last edited by ApoaJonnz; May 19, 2017 at 06:43. Reason: clarification

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May 20, 2017, 10:40		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,674 Rep Power: 65	The built-in feature is only available in v18 and onwards. in v17 and before, you can write stuff vs time for a single monitor or write all the data at as many locations as you want, but at one time only. If you are super-skilled however, it is possible to just hack Fluent and force it to write a text file containing the result through a UDF or scheme file. This approach is not really a solution because you could always write a bunch of individual monitor files and read them using another code not in Fluent.

May 22, 2017, 10:51		#3
ApoaJonnz New Member Jonas Join Date: Apr 2017 Posts: 5 Rep Power: 8	Thanks for the note regarding V18. I might try that, as we actually should have access to it. I also might try to write the data for all nodes in one file for certain timesteps. I didn't know, that's actually possible. Do you have a quick guide how to set up a monitor such that it writes out the values for all nodes on a surface for e.g. every10th timestep? Thanks for the help!

May 22, 2017, 13:30		#4
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,674 Rep Power: 65	In the GUI go to file=>solution data=> automatic export In the TUI or using a journal file you can write something like... /file/transient-export ascii "filename" surface1 surface2 () temperature pressure x-velocity y-velocity z-veloicty () no yes another-name 20 time-step This writes data in ascii format into a file called filename on surface1 and surface2, it writes temperature, pressure, velocities, etc. You should try these text commands in an interactive session to understand what each one does. Note that in Fluent v17 and onwards, I'm not sure if it's a visual bug or intentional but user created surfaces do not show up in the GUI in the transient export menu. In v16 and before, user created surfaces did show up in this list. Iin v17 & v18 you cannot for example define a plane slice and export transient data on that plane in the GUI (because you cannot select the surface, they simply aren't in the list of surfaces). However, you can still do it using text commands.

May 22, 2017, 15:21		#5
ApoaJonnz New Member Jonas Join Date: Apr 2017 Posts: 5 Rep Power: 8	Thank you so much for the quick reply! I'll try that and hope that the amount of data is not too overwhelming...