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|ID||Project||Category||View Status||Date Submitted||Last Update|
|0001237||OpenFOAM||[All Projects] Bug||public||2014-03-25 16:41||2014-06-09 12:43|
|Fixed in Version|
|Summary||0001237: Non negligible mass conservation error in twoPhaseEulerFoam|
|Description||The twoPhaseEulerFoam solver shows a non negligible mass conservation error of the disperse phase. |
Considering cases where there is no transport of disperse phase outside of the system, like a fluidized bed, the total volume of particles inside the system should be preserved. However, small errors are observed at each time step, which accumulate and lead to quite important mass loss or addition.
|Steps To Reproduce||The problem can be reproduce using the 'fluidisedBed' tutorial. |
In order to prevent particles from leaving the system, modify the boundary conditions so that alpha.particles is zero at the outlet. The particle velocity is already set to zero at the outlet in the tutorial. Note that this is not required to observe the problem, which happens also without this modification. The modified case is attached.
It can be observed that the error appears from the first time-step (see attached log). The following change in particle mass is observed in 2 seconds of simulation:
- Initial particle volume fraction: 2.75015
- Final particle volume fraction: 2.75553
- Total change in volume fraction: 0.00538 ==> 13.45 kg in 2 seconds
Considering the particle density is 2500 kg/m^3, this corresponds to a mass gain of 6.725 kg/s.
|Additional Information||- The problem happens with or without implicit treatment for the particle pressure.|
- The error is limited (but not always removed) introducing multiple outer correctors (with relaxation of alpha if the bed is nearly packed), and using residual controls to ensure that the set of transport equations converges within certain tolerances (the tolerance for alpha has to be quite low). Reducing the time step has similar effects.
|Tags||No tags attached.|
|2014-03-25 16:41||albertop||New Issue|
|2014-03-25 16:41||albertop||File Added: Tutorial.tar.gz|
|2014-06-09 12:42||henry||Note Added: 0003117|
|2014-06-09 12:42||henry||Status||new => closed|
|2014-06-09 12:43||henry||Assigned To||=> henry|
|2014-06-09 12:43||henry||Resolution||open => fixed|