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icoUncoupledKinematicParcelFoam - strange thing

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Old   January 11, 2014, 11:28
Default icoUncoupledKinematicParcelFoam - strange thing
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Tobias Holzmann
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Hi all,

I am building an hydro-cyclone and simulated it with simpleFoam. Now I want to add particels and want to use the solver icoUncoupledKinematicParcelFoam.


The solver is adding particels but after 4 added - no particel is in the domain anymore?:
Code:
Time = 0.006

Evolving kinematicCloud

Solving 3-D cloud kinematicCloud
    531 move-collide subCycles
Cloud: kinematicCloud
    Current number of parcels       = 2
    Current mass in system          = 0.000916088
    Linear momentum                 = (0.000388678 0.00668253 0.00395061)
   |Linear momentum|                = 0.00777268
    Linear kinetic energy           = 0.0574843
    Rotational kinetic energy       = 0.0325214
    model1:
        number of parcels added     = 2
        mass introduced             = 0.000916088
    Parcels absorbed into film      = 0
    New film detached parcels       = 0

ExecutionTime = 606.33 s  ClockTime = 628 s

Time = 0.0061

Evolving kinematicCloud

Solving 3-D cloud kinematicCloud

--> Cloud: kinematicCloud injector: model1
    Added 1 new parcels

    530 move-collide subCycles
Cloud: kinematicCloud
    Current number of parcels       = 0
    Current mass in system          = 0
    Linear momentum                 = (0 0 0)
   |Linear momentum|                = 0
    Linear kinetic energy           = 0
    Rotational kinetic energy       = 0
    model1:
        number of parcels added     = 3
        mass introduced             = 0.00137413
    Parcels absorbed into film      = 0
    New film detached parcels       = 0

ExecutionTime = 615.79 s  ClockTime = 638 s

Well I have not many experiance with that solver - especially with the settings I have to make in the Cloud file. I showed the variables in red I am not 100% sure of the meaning. Maybe someone can clear my mind:

My file is the following:
Code:
solution
{
    active          true;
    coupled         false;
    transient       yes;
    cellValueSourceCorrection off;

    interpolationSchemes
    {
        rho             cell;
        U               cellPoint;
        mu              cell;
    }

    integrationSchemes
    {
        U               Euler;
    }
}

constantProperties
{
    rho0            1.2;           // Air + particel load ?
    youngsModulus   6e8;   // not sure about
    poissonsRatio   0.35;    // not sure about
}

subModels
{
    particleForces
    {
        sphereDrag;
        gravity;
    }

    injectionModels
    {
        model1
        {
            type            patchFlowRateInjection;
        patchName        inlet;
        duration        2;
        concentration   0.6;              // parcel concentration in my fluid?      
            parcelsPerSecond 500;
        meanParticleDiameter 0.003;  // for what?
 
        nParticle        1000;            // max particle in domain ?

            massTotal       0.5;           // max mass in the domain ?

            parcelBasisType fixed;    // dont know
            SOI             0;                     // ?
            sizeDistribution
            {
                type        fixedValue;          // particle have fixed sizes
                 fixedValueDistribution        // the sizes the particels can have ? 
                {
                    value   0.006;             
            value   0.01;
                    value   0.001;
                    value   0.015;
            value   0.004;
            value   0.009;
                }
            }
        }
    }

    dispersionModel none;

    patchInteractionModel none;

    surfaceFilmModel none;

    collisionModel pairCollision;

    pairCollisionCoeffs
    {
        maxInteractionDistance  0.006;

        writeReferredParticleCloud no;

        pairModel pairSpringSliderDashpot;

        pairSpringSliderDashpotCoeffs
        {
            useEquivalentSize   no;
            alpha               0.12;
            b                   1.5;
            mu                  0.52;
            cohesionEnergyDensity 0;
            collisionResolutionSteps 12;
        };

        wallModel    wallLocalSpringSliderDashpot;

        wallLocalSpringSliderDashpotCoeffs
        {
            useEquivalentSize no;
            collisionResolutionSteps 12;
            ".*Wall"
            {
                youngsModulus   1e10;
                poissonsRatio   0.23;
                alpha           0.12;
                b               1.5;
                mu              0.43;
                cohesionEnergyDensity 0;
            }
        };
    }
}


Are there any tutorials available (not the hopper one?)

Maybe I have to use a other particel solver for my problem?

Thanks in advance
Tobi
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Old   January 15, 2014, 20:55
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hello, Tobi.
actually, i can not help you very much, because i am a rookie.
but i know, "SOI" means " start of injection". specifically, in your code, it means model1 begins to inject particles at 0 second.
" nParticle" means the number of particles that one parcel contains.
"massTotal" dose not determine anything when you set the "parcelBasicType" as "fixed".

ok, that is all i can do for you.
best regards.
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Old   January 15, 2014, 22:07
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hello, Tobi.
actually, i can not help you very much, because i am a rookie.
but i know, "SOI" means " start of injection". specifically, in your code, it means model1 begins to inject particles at 0 second.
" nParticle" means the number of particles that one parcel contains.
"massTotal" dose not determine anything when you set the "parcelBasicType" as "fixed".

ok, that is all i can do for you.
best regards.
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Old   January 16, 2014, 10:29
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Hello Tobias,

i guess we know each other. Here are some of the information you need referring to your problem with the meaning of some of the aspects concering the cloud-File.

Code:
constantPoperties
youngsModulus 6e8;          // E-Modul
poissonsRatio 0.35;          // Poissonzahl
I just worked with patchInjection as injectionModel and not with patchFlowRateInjection, so in the following these information can be provided referring to this part:

Code:
nParticle: total amount of particles you want to inject
massTotal: total mass of the particles in kg
SOI: Start of Injection (when particles are loaded on the streamlines of your main-fluid-flow

pairCollisionCoeffs

maxInteractionDistance: maximal distance of action between particles (max. Beeinflussungsdistanz)

wallModel wallLocalSpringSliderDashpot: describes the influence of particle with the wand (Partikel-WandStoß)


collisonReslutionSteps 12

youngsModuls: E-Modul
b: Federgesetzexponent
alpha: Restitution coefficient
poissonsRatio: Poissonnumber
mu: Reibungskoeffizient
cohesionEnegryDistance: Bindungsenergie [J/m³]
I hope i could help you a liitle bit. Maybe somebody else is/was also working with icoUncoupledKinematicParcelFoam and know the rest od the meanings.

Greetings, Sanjar
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Old   August 24, 2015, 04:58
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Hi Tobias,

Were you able get answers to your doubts? I am interested to know.
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Old   October 5, 2017, 08:20
Smile alpha is not equal to coefficient of restitution
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Hi Sanjar,

The information you provided on this topic is quite useful however, I found an error and I would like to mention it so that others won't end up disappointed after simulating and probably they will not have to endlessly try different settings to find the bug.

The "alpha" is not equal to the coefficient of restitution, but they are related as shown in Fig.4 page 243 of Y. Tsuji, T. Tanaka, T. Ishida, Lagrangian numerical simulation of plug flow of cohesionless particles in a horizontal pipe, Powder Technology, Volume 71, Issue 3, September 1992, Pages 239-250, ISSN 0032-5910, https://doi.org/10.1016/0032-5910(92)88030-L.
(http://www.sciencedirect.com/science...3259109288030L)

For example (taken from that graph), if Coefficient of Restitution=1, then alpha=0.01.

Hope this will help some others

Regards,
Ronith Stanly
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