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[swak4Foam] reactingMultiPhaseEulerFoam problems with groovyBC

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Old   July 1, 2016, 10:50
Default reactingMultiPhaseEulerFoam problems with groovyBC
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Dear All,

Would it be possible please to help me with the below issue.
Maybe some of you already stumbled in this problem and solved it.
I am dealing with simulations of fluidized beds of particles. In particular I have to perform simulations where the air flow from the bed distribution grid is variable with time and from point to point of the grid.
With twoPhaseEulerFoam version 2.4.0 I was able to use groovyBC to specify the time and position dependence of the velocity at the distribution grid. Also I was able to compute the minimum fluidization velocity for comparison with experimental data by increasing the velocity at the distribution grid over time.
To do this I used as a boundary condition in the U.air file:
Code:
    inlet
    {
        aliases {
                 alphaPart alpha.particles;
                 alphaAir  alpha.air;
                }
        type      groovyBC;   
        variables (
                   "t=time();"
                   "u0=0.3000;"
                   "u1=0.6000;"
                   "t0=5.0;"
                   "t1=7.0;"
                   "uf=max(u0,min((u1-u0)/(t1-t0)*(t-t0)+u0,u1));"
                   "inVel=uf/min(1.0-alphaPart,0.38);" 
                   );
        valueExpression    "vector(0,inVel,0)";
        value              $internalField;
    }
With twoPhaseEulerFoam I was able to match the experimental values pretty well. Basically I tried to reproduce the functionality of the InterstitialInletVelocity bc by dividing the prescribed surface velocity by the local void fraction.

Code:
"inVel=uf/min(1.0-alphaPart,0.38);"
With twoPhaseEulerFoam version 2.4 this seems to work fine.

I tried to do the same with reactingMultiphaseEulerFoam from release 3.0.1 of OF since I would like to expand my simulation scope including multiple particles phases with different diameter and properties and mass exchange between the phases. Unfortunately I run into a problem that I was not able to overcome.
The problem is readily apparent even in the simplest of cases. At first I thought that I made some mistakes in the case setup for the new solver but in the end I was able to reproduce it using the fluidized bed tutorial from reactingTwophaseEulerFoam with small modification to adapt it to reactingMultiphaseEulerFoam.
The case is quite simple. Setting a surface velocity of 0.1 m/s using InterstitialInletVelocity
Code:
    inlet
    {
        type               interstitialInletVelocity;
        inletVelocity      uniform (0 0.1 0);
        alpha              alpha.air;
        value              $internalField;
    }
I got the results reported in the figures and video test-01*. After about 1 s we have a bubbling flow that is statistically stable and that is fine. The simulation time is 2.0 s and the simulation run smoothly without any problem.
If I try the same using the groovyBC boundary conditions, that worked for twoPhaseEulerFoam version 2.4.0, I basically obtain plugs of particles that are shot out of the computational domain and the simulation crash with a segfault after 0.15 s. See attachments test-02*
This strange behavior happens also if I specify a surface velocity of 0 m/s as shown in the attachments test-03*
Code:
    inlet
    {
        aliases {
                 alphaPart alpha.particles;
                 alphaAir  alpha.air;
                }
        type      groovyBC;   
        variables (
                   "t=time();"
                   "u0=0.0000;"
                   "u1=0.0000;"
                   "t0=0.0;"
                   "t1=2.0;"
                   "uf=max(u0,min((u1-u0)/(t1-t0)*(t-t0)+u0,u1));"
                   "inVel=uf/min(1.0-alphaPart,0.38);" 
                   );
        valueExpression    "vector(0,inVel,0)";
        value              $internalField;
    }
I was able to repruce the same behaviour also using reactingtwoPhaseEulerFoam and twoPhaseEulerFoam from OF 3.0.1.

What am I missing? The groovyBC worked fine with 2.4. Have I to modify my boundary condition somehow to meet some requirement of reactingMultiphaseEulerFoam 3.0.1?
It is possible at all to use groovyBC with vertion 3.0.1 to do the same thing as in twoPhaseEulerFoam 2.4.0
Do I have to write my own BC to implement time a space variation of velocity at the inlet grid?
Any help from the community is appreciated

Best Regards
Luca

P.S. I have attached the test file I have derived from the original tutorial in tutorials/multiphase/reactingTwoPhaseEulerFoam/RAS/fluidisedBed/
To meet the file size requirements I have removed the polymesh directory, but the mesh is the same as in the tutorial.
The pictures are in the following posts.
Attached Files
File Type: zip test-01.zip (28.4 KB, 9 views)
File Type: zip test-02.zip (27.2 KB, 2 views)
File Type: zip test-03.zip (27.2 KB, 4 views)
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Old   July 1, 2016, 10:52
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Test 01 images
Attached Images
File Type: png test-01-t=0.10.png (19.3 KB, 22 views)
File Type: png test-01-t=0.20.png (26.8 KB, 15 views)
File Type: png test-01-t=0.30.png (42.6 KB, 16 views)
File Type: png test-01-t=0.50.png (70.4 KB, 22 views)
File Type: png test-01-t=2.00.png (56.3 KB, 17 views)
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Old   July 1, 2016, 10:52
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Test 02 Images
Attached Images
File Type: png test-02-t=0.05.png (20.1 KB, 6 views)
File Type: png test-02-t=0.10.png (30.1 KB, 7 views)
File Type: png test-02-t=0.15.png (40.1 KB, 6 views)
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Old   July 1, 2016, 10:53
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Test 03 Images
Attached Images
File Type: png test-03-t=0.05.png (20.5 KB, 6 views)
File Type: png test-03-t=0.10.png (32.0 KB, 5 views)
File Type: png test-03-t=0.15.png (45.7 KB, 7 views)
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Old   December 13, 2016, 06:46
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Sebastien L
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Hello, just seen your message. Even if i cannot really help you, i'm a bit surprised because you say that your are modeling particles, and you are using a laminar phase with no viscosity for your model, not a granular phase.
In fact the reactingmultiphaseeulerfoam is not equivalent to the reactingtwophaseeulerfoam because there is no granular therory included into it. It treats the phases a bit differently, with sharpning on interphase between fluids but keeping euler-euler modeling of phases inside the fluid with individual transport equation for phases but common pressure.
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boundary condition, groovybc, time, twophaseeulerfoam, variable

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