Exemplo n.º 1
0
void Foam::MaxwellianThermal<CloudType>::correct
(
    typename CloudType::parcelType& p,
    const wallPolyPatch& wpp
)
{
    vector& U = p.U();

    scalar& Ei = p.Ei();

    label typeId = p.typeId();

    label wppIndex = wpp.index();

    label wppLocalFace = wpp.whichFace(p.face());

    vector nw = p.normal();
    nw /= mag(nw);

    // Normal velocity magnitude
    scalar U_dot_nw = U & nw;

    // Wall tangential velocity (flow direction)
    vector Ut = U - U_dot_nw*nw;

    CloudType& cloud(this->owner());

    Random& rndGen(cloud.rndGen());

    while (mag(Ut) < SMALL)
    {
        // If the incident velocity is parallel to the face normal, no
        // tangential direction can be chosen.  Add a perturbation to the
        // incoming velocity and recalculate.

        U = vector
        (
            U.x()*(0.8 + 0.2*rndGen.scalar01()),
            U.y()*(0.8 + 0.2*rndGen.scalar01()),
            U.z()*(0.8 + 0.2*rndGen.scalar01())
        );

        U_dot_nw = U & nw;

        Ut = U - U_dot_nw*nw;
    }

    // Wall tangential unit vector
    vector tw1 = Ut/mag(Ut);

    // Other tangential unit vector
    vector tw2 = nw^tw1;

    scalar T = cloud.boundaryT().boundaryField()[wppIndex][wppLocalFace];

    scalar mass = cloud.constProps(typeId).mass();

    scalar iDof = cloud.constProps(typeId).internalDegreesOfFreedom();

    U =
        sqrt(physicoChemical::k.value()*T/mass)
       *(
            rndGen.GaussNormal()*tw1
          + rndGen.GaussNormal()*tw2
          - sqrt(-2.0*log(max(1 - rndGen.scalar01(), VSMALL)))*nw
        );

    U += cloud.boundaryU().boundaryField()[wppIndex][wppLocalFace];

    Ei = cloud.equipartitionInternalEnergy(T, iDof);
}
void Foam::PatchInteractionModel<CloudType>::patchData
(
    typename CloudType::parcelType& p,
    const polyPatch& pp,
    const scalar trackFraction,
    const tetIndices& tetIs,
    vector& nw,
    vector& Up
) const
{
    const fvMesh& mesh = this->owner().mesh();

    const volVectorField& Ufield =
        mesh.objectRegistry::lookupObject<volVectorField>(UName_);

    label patchI = pp.index();
    label patchFaceI = pp.whichFace(p.face());

    vector n = tetIs.faceTri(mesh).normal();
    n /= mag(n);

    vector U = Ufield.boundaryField()[patchI][patchFaceI];

    // Unless the face is rotating, the required normal is n;
    nw = n;

    if (!mesh.moving())
    {
        // Only wall patches may have a non-zero wall velocity from
        // the velocity field when the mesh is not moving.

        if (isA<wallPolyPatch>(pp))
        {
            Up = U;
        }
        else
        {
            Up = vector::zero;
        }
    }
    else
    {
        vector U00 = Ufield.oldTime().boundaryField()[patchI][patchFaceI];

        vector n00 = tetIs.oldFaceTri(mesh).normal();

        // Difference in normal over timestep
        vector dn = vector::zero;

        if (mag(n00) > SMALL)
        {
            // If the old normal is zero (for example in layer
            // addition) then use the current normal, meaning that the
            // motion can only be translational, and dn remains zero,
            // otherwise, calculate dn:

            n00 /= mag(n00);

            dn = n - n00;
        }

        // Total fraction thought the timestep of the motion,
        // including stepFraction before the current tracking step
        // and the current trackFraction
        // i.e.
        // let s = stepFraction, t = trackFraction
        // Motion of x in time:
        // |-----------------|---------|---------|
        // x00               x0        xi        x
        //
        // where xi is the correct value of x at the required
        // tracking instant.
        //
        // x0 = x00 + s*(x - x00) = s*x + (1 - s)*x00
        //
        // i.e. the motion covered by previous tracking portions
        // within this timestep, and
        //
        // xi = x0 + t*(x - x0)
        //    = t*x + (1 - t)*x0
        //    = t*x + (1 - t)*(s*x + (1 - s)*x00)
        //    = (s + t - s*t)*x + (1 - (s + t - s*t))*x00
        //
        // let m = (s + t - s*t)
        //
        // xi = m*x + (1 - m)*x00 = x00 + m*(x - x00);
        //
        // In the same form as before.

        scalar m =
            p.stepFraction()
          + trackFraction
          - (p.stepFraction()*trackFraction);

        // When the mesh is moving, the velocity field on wall patches
        // will contain the velocity associated with the motion of the
        // mesh, in which case it is interpolated in time using m.
        // For other patches the face velocity will need to be
        // reconstructed from the face centre motion.

        const vector& Cf = mesh.faceCentres()[p.face()];

        vector Cf00 = mesh.faces()[p.face()].centre(mesh.oldPoints());

        if (isA<wallPolyPatch>(pp))
        {
            Up = U00 + m*(U - U00);
        }
        else
        {
            Up = (Cf - Cf00)/this->owner().time().deltaTValue();
        }

        if (mag(dn) > SMALL)
        {
            // Rotational motion, nw requires interpolation and a
            // rotational velocity around face centre correction to Up
            // is required.

            nw = n00 + m*dn;

            // Cf at tracking instant
            vector Cfi = Cf00 + m*(Cf - Cf00);

            // Normal vector cross product
            vector omega = (n00 ^ n);

            scalar magOmega = mag(omega);

            // magOmega = sin(angle between unit normals)
            // Normalise omega vector by magOmega, then multiply by
            // angle/dt to give the correct angular velocity vector.
            omega *=
                Foam::asin(magOmega)
               /(magOmega*this->owner().time().deltaTValue());

            // Project position onto face and calculate this position
            // relative to the face centre.
            vector facePos =
                p.position()
              - ((p.position() - Cfi) & nw)*nw
              - Cfi;

            Up += (omega ^ facePos);
        }

        // No further action is required if the motion is
        // translational only, nw and Up have already been set.
    }
}
Exemplo n.º 3
0
void Foam::MixedDiffuseSpecular<CloudType>::correct
(
    typename CloudType::parcelType& p
)
{
    vector& U = p.U();

    scalar& Ei = p.Ei();

    label typeId = p.typeId();

    const label wppIndex = p.patch();

    const polyPatch& wpp = p.mesh().boundaryMesh()[wppIndex];

    label wppLocalFace = wpp.whichFace(p.face());

    const vector nw = p.normal();

    // Normal velocity magnitude
    scalar U_dot_nw = U & nw;

    CloudType& cloud(this->owner());

    Random& rndGen(cloud.rndGen());

    if (diffuseFraction_ > rndGen.scalar01())
    {
        // Diffuse reflection

        // Wall tangential velocity (flow direction)
        vector Ut = U - U_dot_nw*nw;

        while (mag(Ut) < small)
        {
            // If the incident velocity is parallel to the face normal, no
            // tangential direction can be chosen.  Add a perturbation to the
            // incoming velocity and recalculate.

            U = vector
            (
                U.x()*(0.8 + 0.2*rndGen.scalar01()),
                U.y()*(0.8 + 0.2*rndGen.scalar01()),
                U.z()*(0.8 + 0.2*rndGen.scalar01())
            );

            U_dot_nw = U & nw;

            Ut = U - U_dot_nw*nw;
        }

        // Wall tangential unit vector
        vector tw1 = Ut/mag(Ut);

        // Other tangential unit vector
        vector tw2 = nw^tw1;

        scalar T = cloud.boundaryT().boundaryField()[wppIndex][wppLocalFace];

        scalar mass = cloud.constProps(typeId).mass();

        direction iDof = cloud.constProps(typeId).internalDegreesOfFreedom();

        U =
            sqrt(physicoChemical::k.value()*T/mass)
           *(
                rndGen.scalarNormal()*tw1
              + rndGen.scalarNormal()*tw2
              - sqrt(-2.0*log(max(1 - rndGen.scalar01(), vSmall)))*nw
            );

        U += cloud.boundaryU().boundaryField()[wppIndex][wppLocalFace];

        Ei = cloud.equipartitionInternalEnergy(T, iDof);
    }
    else
    {
        // Specular reflection

        if (U_dot_nw > 0.0)
        {
            U -= 2.0*U_dot_nw*nw;
        }
    }

}
bool Foam::LocalInteraction<CloudType>::correct
(
    typename CloudType::parcelType& p,
    const polyPatch& pp,
    bool& keepParticle,
    const scalar trackFraction,
    const tetIndices& tetIs
)
{
    label patchI = patchData_.applyToPatch(pp.index());

    if (patchI >= 0)
    {
        vector& U = p.U();
        bool& active = p.active();

        typename PatchInteractionModel<CloudType>::interactionType it =
            this->wordToInteractionType
            (
                patchData_[patchI].interactionTypeName()
            );

        switch (it)
        {
            case PatchInteractionModel<CloudType>::itEscape:
            {
                scalar dm = p.mass()*p.nParticle();

                keepParticle = false;
                active = false;
                U = vector::zero;
                nEscape_[patchI]++;
                massEscape_[patchI] += dm;
                if (writeFields_)
                {
                    label pI = pp.index();
                    label fI = pp.whichFace(p.face());
                    massEscape().boundaryField()[pI][fI] += dm;
                }
                break;
            }
            case PatchInteractionModel<CloudType>::itStick:
            {
                scalar dm = p.mass()*p.nParticle();

                keepParticle = true;
                active = false;
                U = vector::zero;
                nStick_[patchI]++;
                massStick_[patchI] += dm;
                if (writeFields_)
                {
                    label pI = pp.index();
                    label fI = pp.whichFace(p.face());
                    massStick().boundaryField()[pI][fI] += dm;
                }
                break;
            }
            case PatchInteractionModel<CloudType>::itRebound:
            {
                keepParticle = true;
                active = true;

                vector nw;
                vector Up;

                this->owner().patchData(p, pp, trackFraction, tetIs, nw, Up);

                // Calculate motion relative to patch velocity
                U -= Up;

                scalar Un = U & nw;
                vector Ut = U - Un*nw;

                if (Un > 0)
                {
                    U -= (1.0 + patchData_[patchI].e())*Un*nw;
                }

                U -= patchData_[patchI].mu()*Ut;

                // Return velocity to global space
                U += Up;

                break;
            }
            default:
            {
                FatalErrorIn
                (
                    "bool LocalInteraction<CloudType>::correct"
                    "("
                        "typename CloudType::parcelType&, "
                        "const polyPatch&, "
                        "bool&, "
                        "const scalar, "
                        "const tetIndices&"
                    ") const"
                )   << "Unknown interaction type "
                    << patchData_[patchI].interactionTypeName()
                    << "(" << it << ") for patch "
                    << patchData_[patchI].patchName()
                    << ". Valid selections are:" << this->interactionTypeNames_
                    << endl << abort(FatalError);
            }
        }

        return true;
    }

    return false;
}