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-   -   inject different sized particles (http://www.cfd-online.com/Forums/openfoam-solving/113796-inject-different-sized-particles.html)

czhao86 February 26, 2013 18:47

inject different sized particles
 
Hi Foamers,

I do not have any idea about injection type, except the doc I find in the tutorials. Now I can only inject one sized particles.

Code:

        sizeDistribution
        {
            type        fixedValue;
            fixedValueDistribution
            {
                value  0.2;
            }
        }

How can I inject two sized particles, like 0.1 and 0.2 at the same time?

niklas February 27, 2013 03:45

If its important that the size is either 0.1 or 0.2, I would use 2 injectors

czhao86 February 27, 2013 11:16

Quote:

Originally Posted by niklas (Post 410353)
If its important that the size is either 0.1 or 0.2, I would use 2 injectors

Thank you for your reply.

So should I use two 'CloudProperties' files or two injection in the same 'CloudProperties' file?

czhao86 March 6, 2013 15:25

does anyone have some ideas?

ris March 6, 2013 16:57

Hello czhao86,

I just saw this and it might be useful to you http://www.openfoam.org/version2.2.0...-modelling.php
You could specifiy two injectors of the same model having different size distributions.
Also you only need one sprayCloudProperties file.

regards,

ris.

czhao86 March 6, 2013 18:08

Thank you for your reply, ris.

I am using icoUncoupledKinematicParcelFoam, whose injection is like the following

Code:

solution
{
    active          true;
    coupled        false;
    transient      yes;
    cellValueSourceCorrection off;

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

    integrationSchemes
    {
        U              Euler;
    }

    sourceTerms
    {
        schemes
        {
        // Scheme and under-relaxation factor
          U              semiImplicit 0.5;
//        U              explicit 1.0;
        }
    }

}

constantProperties
{
    parcelTypeId    1;

    rhoMin          1e-16;
    minParticleMass 1.0e-15;

    rho0            1;
    youngsModulus  6e8;
    poissonsRatio  0.35;

    constantVolume  false;
}

subModels
{
    particleForces
    {
        sphereDrag;
        gravity;
    }

    injectionModel manualInjection;

    dispersionModel none;

    patchInteractionModel standardWallInteraction;

    heatTransferModel none;

    surfaceFilmModel none;

    collisionModel pairCollision;

    radiation off;

    manualInjectionCoeffs
    {
        massTotal      0;
        parcelBasisType fixed;
        nParticle      1;
        SOI            0;
        positionsFile  "kinematicCloud0Positions";
        U0              (0 0 0);
        sizeDistribution
        {
            type        fixedValue;
            fixedValueDistribution
            {
                value  0.1;
            }
        }
    }

pairCollisionCoeffs
    {
        // Maximum possible particle diameter expected at any time
        maxInteractionDistance  0.1;

        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;
            walls
            {
                youngsModulus  1e10;
                poissonsRatio  0.23;
                alpha          0.12;
                b              1.5;
                mu              0.43;
        cohesionEnergyDensity 0;
            }
        };
    }

    standardWallInteractionCoeffs
    {
        //type            stick;
        type            rebound;
    }
}


cloudFunctions
{

}

I am not sure where to add the second injection, as the format is a little different, but certainly thank you for your reply.

czhao86 March 7, 2013 17:20

Quote:

Originally Posted by ris (Post 412089)
Hello czhao86,

I just saw this and it might be useful to you http://www.openfoam.org/version2.2.0...-modelling.php
You could specifiy two injectors of the same model having different size distributions.
Also you only need one sprayCloudProperties file.

regards,

ris.

I figured out openfoam 2.2.0 has a different format of 'injectionModels' even in the tutorials, compared to 2.1.1.

I saw this webpage but did not realize its importance.

Thank you for giving me a hint.

camzis June 16, 2015 05:15

Diifferent numbers of particle injection?
 
Dear Foamers,
I'm currently working with the solver iconUncoupledKinematicParcelFoam (lagrangian).
I need to inject a different number of particles at each time step.
I'm currently using the model "patchInjection" in the file kinematicCloudProperties.
The problem is, I dont know how to make the number of particels vary.
Is there a way to force the number of particles to vary by wether providing a table (for number of particles vs. time) or as a function?
Any suggestions, ideas are very welcome.
Please, my master thesis depends on this.
Regards!
Mamadou.

Dust July 8, 2015 20:06

Normal Distribution
 
Quote:

Originally Posted by czhao86 (Post 412074)
does anyone have some ideas?

I think you can define the size of particles to be normal distributed. For instance:

sizeDistribution
{
type normal;
normalDistribution
{
expectation 0.0001;
variance 2.16e-10;
minValue 0.00005;
maxValue 0.00015;
}
}

Hope it helps

Zonghao


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