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| ID | Project | Category | View Status | Date Submitted | Last Update |
| 0000156 | OpenFOAM | [All Projects] Bug | public | 2011-03-04 19:42 | 2011-03-04 22:50 |
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| Reporter | pbryant | |
| Assigned To | henry | |
| Priority | normal | Severity | minor | Reproducibility | always |
| Status | closed | Resolution | fixed | |
| Platform | Linux | OS | Ubuntu | OS Version | 10.10 |
| Product Version | 1.7.x | |
| Target Version | | Fixed in Version | | |
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| Summary | 0000156: High viscosity gives wrong result in multiphase problem |
| Description | The InterFoam solver seems to be giving the wrong answer when the viscosity is large. To demonstrate this I generated a test case called waterDrop which I uploaded as a zip file. It is essentially identical to the damBreak tutorial except that the liquid is now in a rectangular blob suspended above the ground by about 0.218 meters. At t=0 it is dropped and falls down. The expected fall time can be obtained from the usual physics formula: t = sqrt(2*h/g), which in this case is about 0.21 seconds. In the simulation I varied the viscosity of the water, not of the air. It works as expected for low viscosity, but surprisingly the fall time is found to increase when the water viscosity is increased to a large value. As uploaded, the viscosity of the "water" has been increased from 1e-6 to 1e0 and the fall time has increased to about 0.78 seconds. When further increased to 1e2 the water actually floats upwards and disappears out the atmosphere patch! |
| Steps To Reproduce | The viscosity nu for phase1 is set in the file constant/transportProperties. To run and generate log file, enter the commands: blockMesh, checkMesh, setFields, interFoam | tee log1. |
| Additional Information | I have tried adjusting most of the parameters in the fvSolution file with little success. Setting momentumPredictor to yes helps somewhat as does increasing nCorrectors but drastically increases the run time and doesn't completely fix the problem. Decreasing Courant number in the controlDict file also has some beneficial effect. I'm hoping that someone will know how to solve this problem, or else can confirm my suspicion that this is a symptom of some kind of bug in the software.
Thanks - Paul
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| Tags | interFoam, multiphase, viscosity |
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| Attached Files |  waterDrop.zip [^] (8,315 bytes) 2011-03-04 19:42 |
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