[tiatabasco]

I would like to know how can I assign two regions on the same surface for example in figure bottom wall and Outlet on the same plane but need to be two regions. I created an extruded tank. but I do not know how to include the outlet.

[me3840]

Why do they need to be in two regions? They can just be two separate boundaries in one region.

[tiatabasco]

Hey thanks. I already did it that way. Now I Have another issue and that is how do I stop the iterations for example when the water has all drained down stop at a particular volume of fraction of water)? Its a multiphase simulation with water(liquid) and air (gas) and I have used VOF model.

[marmot]

Thats a good question I would monitor the mass of water in the system,

Create a field function
$VolumeFractionWater*$DensityWater

Create a report, volume integral, using the whole region and the field function you created

right click on report created and create plot and monitor or just monitor

go to stopping criteria, right click and create new criteria from monitor and choose the volumeIntegral one,

now you can set a min, would not use zero but something like 0.1% of the starting mass of water,

[me3840]

You don't have to do a field function for this, you could just make a sum report of the water volume fraction. Once it drops below some threshold then stop.

If you want a physical means, you need to make a field function:
$VolumeFractionWater*$DensityWater*$Volume

[tiatabasco]

I made a
-new Report with Volume average and scalar field function as Volume Fraction of H2O and parts as the region of fluid
-created monitor and plots
-I created new Stopping criteria from Monitor and selected Volume Average and
I know my initial Volume Fraction of H2O is 0.62 and I set the the maximum limit as 0.1. I wanna know what does maximum and minimum really mean?

[marmot]

OK you now have the general idea how to create a stopping criteria from a monitor,
but I still think it is easier to think in terms of mass or volume of water, for example say you start with 5kg and when you have 50g in the tank stop the simulation,


I believe me3840 suggested a sum report, which would be like volume, but I don't think a volume average is the best way,

[me3840]

Originally Posted by marmot

I believe me3840 suggested a sum report, which would be like volume, but I don't think a volume average is the best way,

My suggestion was equivalent to yours (mass), I just put volume in a sum report instead of using a volume integral report.

The 'min' and 'max' for the stopping criteria are threshold. So if a value drops below the minimum, it stops iterating. Similarly, if it exceeds some maximum, it stops. If you want to stop when the tank is drained, setting a minimum would work.

[tiatabasco]

Hallo marmot!

Thanks a lot for your advice. I would like to know one more think. Is there any way I can plot a height of water column vs. Time? That would be ma main concern on how much time to empty the tank

[tiatabasco]

HAllo me3840!

Thank you so much for your reply. Its working perfectly now. I used volume sum