Change settings during a simulation

RaiderDoctor · January 29, 2017, 22:22

Hey guys,
I'm currently running an FSI simulation on 17.2. Because the simulation is complex, I've set the program to have restart points every 20 time steps. At about my 300 time step, I get an error message that says fluent has detected a negative cell volume. Thus far, changing the time step size has not solved the issue. I'd like to adjust the dynamic mesh to counteract this, but every time I try it deletes my solution files. I've got about a week of straight calculation in this, is there any way that I can change settings and troubleshoot the problem mid-simulation? Thanks in advance.

RaiderDoctor · May 31, 2017, 16:20

To anyone still wondering about this, I finally solved it. You cannot directly change the settings within the setup of Fluent mid-simulation. You can, however, adjust certain settings within the solution.

In this particular instance, I wanted to change the dynamic mesh settings from spring-based to diffusion-based. To do this, simple double-click on the solution cell in Workbench and change the setting.

You do need to need to ensure that you are on the time step that you will be restarting from. As a refresher, you check this by clicking File ->Solution Files-> Step Number you are restarting from. Hope this helps.

BlackHeartInertia · June 20, 2017, 19:48

That is true. Al changes in the setup must be perfomed from solution..

I have a question. Sometimes I need to change the mesh or add a new named surface. In that case you cant open mesh and change it ... in that case you must initialize your simulation with the older data?? (Instead of hibryd ir standard..)... or is there another way to change your mesh??

Sent from my SM-G570M using CFD Online Forum mobile app

RaiderDoctor · June 20, 2017, 19:56

If I understand you correctly, you'd like to add new named selections to your mesh during a simulation? This, unfortunately, can't be done. While it seems simple enough, Fluent will see this as a completely new mesh. If you absolutely can't restart your simulation, try different post-processing techniques to capture what a named selection would yield, or simply make a note of it and make the change during a later revision of the simulation.

Hope this helps!

BlackHeartInertia · June 20, 2017, 20:15

I was wondering because once I realized I had forgotten some zones jiji and I needed to change a little bit the geometry
Thanks for your answer

January 29, 2017, 22:22	Change settings during a simulation	#1
RaiderDoctor Senior Member Join Date: Dec 2016 Posts: 152 Rep Power: 11	Hey guys, I'm currently running an FSI simulation on 17.2. Because the simulation is complex, I've set the program to have restart points every 20 time steps. At about my 300 time step, I get an error message that says fluent has detected a negative cell volume. Thus far, changing the time step size has not solved the issue. I'd like to adjust the dynamic mesh to counteract this, but every time I try it deletes my solution files. I've got about a week of straight calculation in this, is there any way that I can change settings and troubleshoot the problem mid-simulation? Thanks in advance.

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May 31, 2017, 16:20		#2
RaiderDoctor Senior Member Join Date: Dec 2016 Posts: 152 Rep Power: 11	To anyone still wondering about this, I finally solved it. You cannot directly change the settings within the setup of Fluent mid-simulation. You can, however, adjust certain settings within the solution. In this particular instance, I wanted to change the dynamic mesh settings from spring-based to diffusion-based. To do this, simple double-click on the solution cell in Workbench and change the setting. You do need to need to ensure that you are on the time step that you will be restarting from. As a refresher, you check this by clicking File ->Solution Files-> Step Number you are restarting from. Hope this helps.

June 20, 2017, 19:48		#3
BlackHeartInertia New Member yardena jodeck Join Date: May 2017 Posts: 29 Rep Power: 10	That is true. Al changes in the setup must be perfomed from solution.. I have a question. Sometimes I need to change the mesh or add a new named surface. In that case you cant open mesh and change it ... in that case you must initialize your simulation with the older data?? (Instead of hibryd ir standard..)... or is there another way to change your mesh?? Sent from my SM-G570M using CFD Online Forum mobile app

June 20, 2017, 19:56		#4
RaiderDoctor Senior Member Join Date: Dec 2016 Posts: 152 Rep Power: 11	If I understand you correctly, you'd like to add new named selections to your mesh during a simulation? This, unfortunately, can't be done. While it seems simple enough, Fluent will see this as a completely new mesh. If you absolutely can't restart your simulation, try different post-processing techniques to capture what a named selection would yield, or simply make a note of it and make the change during a later revision of the simulation. Hope this helps!

June 20, 2017, 20:15		#5
BlackHeartInertia New Member yardena jodeck Join Date: May 2017 Posts: 29 Rep Power: 10	I was wondering because once I realized I had forgotten some zones jiji and I needed to change a little bit the geometry Thanks for your answer