View Issue Details
|ID||Project||Category||View Status||Date Submitted||Last Update|
|0003442||OpenFOAM||Bug||public||2020-02-06 05:09||2020-02-17 16:40|
|Fixed in Version||dev|
|Summary||0003442: Unexpected drop at inlet temperatures noticed in reactingTwoPhaseEulerFoam|
|Description||The problem being simulated is flashing (phase change from liquid to gas) of steam in a convergent-divergent nozzle. Pure liquid enters the nozzle at the inlet and the phases change occurs downstream of the throat due the pressure dropping below the saturation value. The solver being used is the reactingTwoPhaseEulerFoam with the interfaceCompositionPhaseChangeTwoPhaseSystem phase system. The interface composition system being used is the Saturated type with both the constant and the antonie type are tested. A single species exists in each of the phase.|
The phase change is triggered only with specification of a small value of the initial volume fraction of the gas phase (1e-12).
Unexplained temperature drop is developed and convected near the first control volume near the inlet boundary. This leads to low temperatures being transported throughout the nozzle thereby leading to drop in saturation pressures and temperatures.
|Steps To Reproduce||All required files can be downloaded from the links given in pdf file attached|
|Tags||No tags attached.|
REPORT.pdf (265,224 bytes)
||reactingTwoPhaseEulerFoam is under active development and there have been many improvements in OpenFOAM-7 and OpenFOAM-dev. Please re-run your case in the latest OpenFOAM-dev.|
I have tested this case on OpenFoam version 7 and have found the same issues. Please find attached the results file>
I will test the case on OpenFOam-dev within couple of weeks and report.
I have tested this case with latest -dev version of Openfoam and found that the problem still persists.
Please find attached the files
||The case has a few setup problems and takes a long time to run, can you provide an 2D axisymmetric version for testing?|
The temperature issue is caused by an accumulation of error from the pressure work term in the internal energy equation from the very small but non-zero continuity error.
To avoid this kind of error accumulation in pure incompressible phases there is an optional pressureWorkAlphaLimit control which you can set and it resolves the problem.
I have also improved the pressure work term formulation to include a continuity error compensation term:
commit 17afa7d79b09f7d2dbf71f55925c041e0f2bd32f (HEAD -> master, origin/master, origin/HEAD)
Author: Henry Weller <http://openfoam.org>
Date: Mon Feb 17 14:04:45 2020 +0000
reactingEulerFoam::AnisothermalPhaseModel: Added a continuity error compensation term to the internal energy pressure work
Reduced the accumulation of error for incompressible and low compressibility
Thank you Henry for the changes. I will test it when the repository package files are updated and the software is upgraded.
Can I also please request you to upload the new case with the corrected setup problems that I have missed. This will help verification and my studies at the university.
It would make more sense to work on an axisymmetric case; I don't see the need to run this case 3D unless you want to run it LES.
The issue with the phase change occurring only when there is at least some gas is that the current phase-change modelling is not designed for spontaneous flashing; it occurs at the interface between the phases so the interface need s to be present. Funding would be required to develop reactingEulerFoam for flashing calculations.
||Resolved by commit 17afa7d79b09f7d2dbf71f55925c041e0f2bd32f|
|2020-02-06 05:09||sjohn2||New Issue|
|2020-02-06 05:09||sjohn2||File Added: REPORT.pdf|
|2020-02-06 08:27||henry||Note Added: 0011127|
|2020-02-07 07:09||sjohn2||Note Added: 0011142|
|2020-02-16 02:05||sjohn2||Note Added: 0011186|
|2020-02-17 10:27||henry||Note Added: 0011190|
|2020-02-17 14:09||henry||Note Added: 0011191|
|2020-02-17 14:46||sjohn2||Note Added: 0011192|
|2020-02-17 14:56||henry||Note Added: 0011193|
|2020-02-17 16:40||henry||Assigned To||=> henry|
|2020-02-17 16:40||henry||Status||new => resolved|
|2020-02-17 16:40||henry||Resolution||open => fixed|
|2020-02-17 16:40||henry||Fixed in Version||=> dev|
|2020-02-17 16:40||henry||Note Added: 0011195|