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IDProjectCategoryView StatusLast Update
0001700OpenFOAMBugpublic2015-06-15 18:51
Reporteruser1145Assigned Tohenry  
Status closedResolutionno change required 
PlatformGNU/LinuxOSUbuntuOS Version12.04
Summary0001700: Mass conservation in twoPhaseEulerFoam
DescriptionIn fluidizedBed tutorial at outlet an increase in air mass flow rate and total mass flow rate (air+particles) is being observed even though the boundary conditions are set in such a way to ensure the zero particles mass flow out of the domain. We can check the increase in mass flow rate by following commands

patchIntegrate phi.particles inlet = 0
patchIntegrate phi.particles outlet = 0

patchIntegrate phi.air inlet = 0.013
patchIntegrate phi.air outlet = 0.017

Steps To ReproduceNo specific steps are required to reproduce this problem.
Additional InformationThe boundary condition for alpha.particles at inlet and outlet are set to fixedValue = 0 (initially zeroGradient) and 0/U.particles/outlet also fixedValue = 0 (initially zeroGradient) to make sure no particle is moving outside the geometry. It shows no particle is moving in and out of the domain but the air mass flow rate increases.

I was stated in a bug report that this problem has been fixed in 2.3.x but this problem still exist both in 2.3.x and 2.3.1 as well.

Here is the link for previous bug report:

This problem is not present in OpenFOAM2.1.1
TagsNo tags attached.



2015-06-15 18:51

manager   ~0004937

twoPhaseEulerFoam in compressible in OpenFOAM-2.3.x and air is treated as a compressible phase whereas in OpenFOAM-2.1.1 the air is treated as incompressible. So to create the equivalent behavior you would need to select a constant density model for the air.

In the current setup in OpenFOAM-2.3.x the inlet and outlet air fluxes vary over time and will only be equal on average. If you average these fluxes over time for a long enough time after the case has reached a fully-developed state you should find they are equal within the continuity error of the case.

Issue History

Date Modified Username Field Change
2015-05-20 20:53 user1145 New Issue
2015-06-15 18:51 henry Note Added: 0004937
2015-06-15 18:51 henry Status new => closed
2015-06-15 18:51 henry Assigned To => henry
2015-06-15 18:51 henry Resolution open => no change required