Flux reports for transient simulation in Fluent

khaham · March 11, 2017, 06:39

Hi every one, i need to check my flux reports at some moments of simulation time not at the end (example: if my simulation time is 1 min, i want to check my flux reports at time=30 s). it seems that Fluent show flux reports just at the final simulation time. is that possible in Fluent.
thank's in advance.

LuckyTran · March 11, 2017, 07:42

Yes and No.

Fluent only stores the most recent solution and whatever else is needed for it to keep calculating. It doesn't keep track of the solution history. The report only works for the current solution.

You can make a flux monitor and export it over time or make a plot over time.

khaham · March 11, 2017, 08:53

Thank you "LuckyTran" for your great help. Yes, monitoring flux can do the job but the simulation have to run again (for me CPU time is about 02 days) and of course create a flux monitoring.

To perform that i think to use:

Monitors/surface monitors/create/ report type: Integral, Field variable: wall fluxes, total surface heat flux (as i look for energy report) and specify name, plot and the way to get the data.
Am i right?

LuckyTran · March 11, 2017, 13:34

Yes unfortunately this is what happens when you're not able to save a .dat file every iteration and you don't plan far enough. But it is something everyone experiences.

Quote:

Originally Posted by khaham

Monitors/surface monitors/create/ report type: Integral, Field variable: wall fluxes, total surface heat flux (as i look for energy report) and specify name, plot and the way to get the data.
Am i right?

Yes! You might as well write it to a file also if it's going to take 2 days. Otherwise, if you close the case and try to reopen it again, the plots will be reset.

potatocat · April 18, 2017, 05:55

Quote:

Originally Posted by LuckyTran

Yes unfortunately this is what happens when you're not able to save a .dat file every iteration and you don't plan far enough. But it is something everyone experiences.

Yes! You might as well write it to a file also if it's going to take 2 days. Otherwise, if you close the case and try to reopen it again, the plots will be reset.

Hi！ LuckyTran, I have a similar question about monitor function. Could you please help me? I'm working on a transient simulation of air-water two-phrase flow, and I would like to get the water flux of an outlet boundary. But when I use the surface monitors, I find if I choose "mass flow rate" in the report type, I could not get the data of water, only the mixture. So I try the flow rate/phases/volume fraction/water and the outlet boundary. Is this correct for me to get the mass flux?

LuckyTran · April 18, 2017, 09:15

Quote:

Originally Posted by potatocat

But when I use the surface monitors, I find if I choose "mass flow rate" in the report type, I could not get the data of water, only the mixture. So I try the flow rate/phases/volume fraction/water and the outlet boundary. Is this correct for me to get the mass flux?

The way to do this varies slightly with version. But in multiphase, you must specify if you want the mass flow rate of the mixture or individual phases: mixture, phase-1, phase-2, etc. You don't simply select mass flow rate, the default is the mass flow of the mixture.

potatocat · April 19, 2017, 05:13

Thanks for your reply! I agree with you. But I just could not choose water phase in the mass flow rate, and sorry, I don't know how to upload pictures. how could I set in Fluent 15.0 to get this data?

potatocat · April 19, 2017, 05:29

By the way, I've read the help document and found that I could use Flux Reports to calculate the mass flow rate of water(and it's more accurate). But how to set to get the transient data during the whole process? Thanks in advance!

potatocat · April 19, 2017, 05:49

The last method I would use is to record 1. the area-weighted average volume fraction of water;2.the volume flow rate of mixture. And maybe I could get the water flow rate by multiplying them with density of water? is this correct?

Audrius · April 19, 2017, 08:10

When You use monitoring points in Fluent, they make Your simalations slower. You can do it very simple: set data saving interval, run simalation for one minute, and after that go to the CFD-post. In CFD-Post You can look at fluxes in each time step, which were saved during You simulations.

potatocat · April 19, 2017, 08:35

Oh~thanks for your advice! But I'm wondering what about the time saving data... Did you mean only saving water volume fluxes? Maybe that would be faster~ Thanks!

potatocat · April 19, 2017, 08:44

Sorry, I've tried to set in the automatic export. But I could not choose a single face and there is no flux in Quantities drop-down list. Maybe I could only use the write function in monitor instead of plot. And of course, I will set the getting data interval.

March 11, 2017, 06:39	Flux reports for transient simulation in Fluent	#1
khaham New Member kha Join Date: Feb 2016 Posts: 7 Rep Power: 10	Hi every one, i need to check my flux reports at some moments of simulation time not at the end (example: if my simulation time is 1 min, i want to check my flux reports at time=30 s). it seems that Fluent show flux reports just at the final simulation time. is that possible in Fluent. thank's in advance.

March 11, 2017, 07:42		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,754 Rep Power: 66	Yes and No. Fluent only stores the most recent solution and whatever else is needed for it to keep calculating. It doesn't keep track of the solution history. The report only works for the current solution. You can make a flux monitor and export it over time or make a plot over time. khaham and potatocat like this.

March 11, 2017, 08:53	Monitoring flux	#3
khaham New Member kha Join Date: Feb 2016 Posts: 7 Rep Power: 10	Thank you "LuckyTran" for your great help. Yes, monitoring flux can do the job but the simulation have to run again (for me CPU time is about 02 days) and of course create a flux monitoring. To perform that i think to use: Monitors/surface monitors/create/ report type: Integral, Field variable: wall fluxes, total surface heat flux (as i look for energy report) and specify name, plot and the way to get the data. Am i right?

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April 19, 2017, 05:13		#7
potatocat New Member Emma Zhang Join Date: Apr 2017 Posts: 6 Rep Power: 9	Thanks for your reply! I agree with you. But I just could not choose water phase in the mass flow rate, and sorry, I don't know how to upload pictures. how could I set in Fluent 15.0 to get this data?

April 19, 2017, 05:29		#8
potatocat New Member Emma Zhang Join Date: Apr 2017 Posts: 6 Rep Power: 9	By the way, I've read the help document and found that I could use Flux Reports to calculate the mass flow rate of water(and it's more accurate). But how to set to get the transient data during the whole process? Thanks in advance!

April 19, 2017, 05:49		#9
potatocat New Member Emma Zhang Join Date: Apr 2017 Posts: 6 Rep Power: 9	The last method I would use is to record 1. the area-weighted average volume fraction of water;2.the volume flow rate of mixture. And maybe I could get the water flow rate by multiplying them with density of water? is this correct?

April 19, 2017, 08:10		#10
Audrius Member Audrius Join Date: Apr 2015 Location: Kaunas Posts: 30 Rep Power: 11	When You use monitoring points in Fluent, they make Your simalations slower. You can do it very simple: set data saving interval, run simalation for one minute, and after that go to the CFD-post. In CFD-Post You can look at fluxes in each time step, which were saved during You simulations.

April 19, 2017, 08:35		#11
potatocat New Member Emma Zhang Join Date: Apr 2017 Posts: 6 Rep Power: 9	Oh~thanks for your advice! But I'm wondering what about the time saving data... Did you mean only saving water volume fluxes? Maybe that would be faster~ Thanks!

April 19, 2017, 08:44		#12
potatocat New Member Emma Zhang Join Date: Apr 2017 Posts: 6 Rep Power: 9	Sorry, I've tried to set in the automatic export. But I could not choose a single face and there is no flux in Quantities drop-down list. Maybe I could only use the write function in monitor instead of plot. And of course, I will set the getting data interval.