void Foam::SHF::breakupParcel
(
parcel& p,
const scalar deltaT,
const vector& vel,
const liquidMixtureProperties& fuels
) const
{
label cellI = p.cell();
scalar T = p.T();
scalar pc = spray_.p()[cellI];
scalar sigma = fuels.sigma(pc, T, p.X());
scalar rhoLiquid = fuels.rho(pc, T, p.X());
scalar muLiquid = fuels.mu(pc, T, p.X());
scalar rhoGas = spray_.rho()[cellI];
scalar weGas = p.We(vel, rhoGas, sigma);
scalar weLiquid = p.We(vel, rhoLiquid, sigma);
// correct the Reynolds number. Reitz is using radius instead of diameter
scalar reLiquid = p.Re(rhoLiquid, vel, muLiquid);
scalar ohnesorge = sqrt(weLiquid)/(reLiquid + VSMALL);
vector vRel = p.Urel(vel);
scalar weGasCorr = weGas/(1.0 + weCorrCoeff_*ohnesorge);
// droplet deformation characteristic time
scalar tChar = p.d()/mag(vRel)*sqrt(rhoLiquid/rhoGas);
scalar tFirst = cInit_*tChar;
scalar tSecond = 0;
scalar tCharSecond = 0;
// updating the droplet characteristic time
p.ct() += deltaT;
if (weGas > weConst_)
{
if (weGas < weCrit1_)
{
tCharSecond = c1_*pow((weGas - weConst_),cExp1_);
}
else if (weGas >= weCrit1_ && weGas <= weCrit2_)
{
tCharSecond = c2_*pow((weGas - weConst_),cExp2_);
}
else
{
tCharSecond = c3_*pow((weGas - weConst_),cExp3_);
}
}
scalar weC = weBuCrit_*(1.0+ohnCoeffCrit_*pow(ohnesorge, ohnExpCrit_));
scalar weB = weBuBag_*(1.0+ohnCoeffBag_*pow(ohnesorge, ohnExpBag_));
scalar weMM = weBuMM_*(1.0+ohnCoeffMM_*pow(ohnesorge, ohnExpMM_));
bool bag = (weGas > weC && weGas < weB);
bool multimode = (weGas >= weB && weGas <= weMM);
bool shear = (weGas > weMM);
tSecond = tCharSecond*tChar;
scalar tBreakUP = tFirst + tSecond;
if (p.ct() > tBreakUP)
{
scalar d32 =
coeffD_*p.d()*pow(ohnesorge, onExpD_)*pow(weGasCorr, weExpD_);
if (bag || multimode)
{
scalar d05 = d32Coeff_*d32;
scalar x = 0.0;
scalar y = 0.0;
scalar d = 0.0;
scalar px = 0.0;
do
{
x = cDmaxBM_*rndGen_.sample01<scalar>();
d = sqr(x)*d05;
y = rndGen_.sample01<scalar>();
px =
x
/(2.0*sqrt(constant::mathematical::twoPi)*sigma_)
*exp(-0.5*sqr((x-mu_)/sigma_));
} while (y >= px);
p.d() = d;
p.ct() = 0.0;
}
if (shear)
{
scalar dC = weConst_*sigma/(rhoGas*sqr(mag(vRel)));
scalar d32Red = 4.0*(d32*dC)/(5.0*dC - d32);
scalar initMass = p.m();
scalar d05 = d32Coeff_*d32Red;
scalar x = 0.0;
scalar y = 0.0;
scalar d = 0.0;
scalar px = 0.0;
do
{
x = cDmaxS_*rndGen_.sample01<scalar>();
d = sqr(x)*d05;
y = rndGen_.sample01<scalar>();
px =
x
/(2.0*sqrt(constant::mathematical::twoPi)*sigma_)
*exp(-0.5*sqr((x-mu_)/sigma_));
} while (y >= px);
p.d() = dC;
p.m() = corePerc_*initMass;
spray_.addParticle
(
new parcel
(
p.mesh(),
p.position(),
p.cell(),
p.tetFace(),
p.tetPt(),
p.n(),
d,
p.T(),
(1.0 - corePerc_)*initMass,
0.0,
0.0,
0.0,
-GREAT,
p.tTurb(),
0.0,
scalar(p.injector()),
p.U(),
p.Uturb(),
p.X(),
p.fuelNames()
)
);
p.ct() = 0.0;
}
}
}
// Return 'keepParcel'
bool reflectParcel::wallTreatment
(
parcel& p,
const label globalFacei
) const
{
label patchi = p.patch(globalFacei);
label facei = p.patchFace(patchi, globalFacei);
const polyMesh& mesh = spray_.mesh();
if (mesh_.boundaryMesh()[patchi].isWall())
{
// wallNormal defined to point outwards of domain
vector Sf = mesh_.Sf().boundaryField()[patchi][facei];
Sf /= mag(Sf);
if (!mesh.moving())
{
// static mesh
scalar Un = p.U() & Sf;
if (Un > 0)
{
p.U() -= (1.0 + elasticity_)*Un*Sf;
}
}
else
{
// moving mesh
vector Ub1 = U_.boundaryField()[patchi][facei];
vector Ub0 = U_.oldTime().boundaryField()[patchi][facei];
scalar dt = spray_.runTime().deltaT().value();
const vectorField& oldPoints = mesh.oldPoints();
const vector& Cf1 = mesh.faceCentres()[globalFacei];
vector Cf0 = mesh.faces()[globalFacei].centre(oldPoints);
vector Cf = Cf0 + p.stepFraction()*(Cf1 - Cf0);
vector Sf0 = mesh.faces()[globalFacei].normal(oldPoints);
// for layer addition Sf0 = vector::zero and we use Sf
if (mag(Sf0) > SMALL)
{
Sf0 /= mag(Sf0);
}
else
{
Sf0 = Sf;
}
scalar magSfDiff = mag(Sf - Sf0);
vector Ub = Ub0 + p.stepFraction()*(Ub1 - Ub0);
if (magSfDiff > SMALL)
{
// rotation + translation
vector Sfp = Sf0 + p.stepFraction()*(Sf - Sf0);
vector omega = Sf0 ^ Sf;
scalar magOmega = mag(omega);
omega /= magOmega+SMALL;
scalar phiVel = ::asin(magOmega)/dt;
scalar dist = (p.position() - Cf) & Sfp;
vector pos = p.position() - dist*Sfp;
vector vrot = phiVel*(omega ^ (pos - Cf));
vector v = Ub + vrot;
scalar Un = ((p.U() - v) & Sfp);
if (Un > 0.0)
{
p.U() -= (1.0 + elasticity_)*Un*Sfp;
}
}
else
{
// translation
vector Ur = p.U() - Ub;
scalar Urn = Ur & Sf;
/*
if (mag(Ub-v) > SMALL)
{
Info << "reflectParcel:: v = " << v
<< ", Ub = " << Ub
<< ", facei = " << facei
<< ", patchi = " << patchi
<< ", globalFacei = " << globalFacei
<< ", name = " << mesh_.boundaryMesh()[patchi].name()
<< endl;
}
*/
if (Urn > 0.0)
{
p.U() -= (1.0 + elasticity_)*Urn*Sf;
}
}
}
}
else
{
FatalError
<< "bool reflectParcel::wallTreatment(parcel& parcel) const "
<< " parcel has hit a boundary "
<< mesh_.boundary()[patchi].type()
<< " which not yet has been implemented."
<< abort(FatalError);
}
return true;
}
void myLISA_3_InjPos::atomizeParcel
(
parcel& p,
const scalar deltaT,
const vector& vel,
const liquidMixture& fuels
) const
{
const PtrList<volScalarField>& Y = spray_.composition().Y();
label Ns = Y.size();
label cellI = p.cell();
scalar pressure = spray_.p()[cellI];
scalar temperature = spray_.T()[cellI];
//--------------------------------------AL____101015--------------------------------//
// scalar Taverage = p.T() + (temperature - p.T())/3.0;
scalar Taverage = temperature;
//-----------------------------------------END--------------------------------------//
scalar Winv = 0.0;
for(label i=0; i<Ns; i++)
{
Winv += Y[i][cellI]/spray_.gasProperties()[i].W();
}
scalar R = specie::RR*Winv;
// ideal gas law to evaluate density
scalar rhoAverage = pressure/R/Taverage;
//scalar nuAverage = muAverage/rhoAverage;
scalar sigma = fuels.sigma(pressure, p.T(), p.X());
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
// The We and Re numbers are to be evaluated using the 1/3 rule.
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
scalar WeberNumber = p.We(vel, rhoAverage, sigma);
scalar tau = 0.0;
scalar dL = 0.0;
scalar k = 0.0;
scalar muFuel = fuels.mu(pressure, p.T(), p.X());
scalar rhoFuel = fuels.rho(1.0e+5, p.T(), p.X());
scalar nuFuel = muFuel/rhoFuel;
vector uDir = p.U()/mag(p.U());
scalar uGas = mag(vel & uDir);
vector Ug = uGas*uDir;
/*
TL
It might be the relative velocity between Liquid and Gas, but I use the
absolute velocity of the parcel as suggested by the authors
*/
// scalar U = mag(p.Urel(vel));
scalar U = mag(p.U());
p.ct() += deltaT;
scalar Q = rhoAverage/rhoFuel;
const injectorType& it =
spray_.injectors()[label(p.injector())].properties();
if (it.nHoles() > 1)
{
Info << "Warning: This atomization model is not suitable for multihole injector." << endl
<< "Only the first hole will be used." << endl;
}
const vector direction = it.direction(0, spray_.runTime().value());
//--------------------------------CH 101108--------------------------------------------------//
// const vector itPosition = it.position(0);
const injectorModel& im = spray_.injection();
const vector itPosition = it.position(0) + im.injDist(0)*direction/mag(direction);
//------------------------------------END----------------------------------------------------//
scalar pWalk = mag(p.position() - itPosition);
// Updating liquid sheet tickness... that is the droplet diameter
// const vector direction = it.direction(0, spray_.runTime().value());
scalar h = (p.position() - itPosition) & direction;
scalar d = sqrt(sqr(pWalk)-sqr(h));
scalar time = pWalk/mag(p.U());
scalar elapsedTime = spray_.runTime().value();
scalar massFlow = it.massFlowRate(max(0.0,elapsedTime-time));
scalar hSheet = massFlow/(mathematicalConstant::pi*d*rhoFuel*mag(p.U()));
p.d() = min(hSheet,p.d());
if(WeberNumber > 27.0/16.0)
{
scalar kPos = 0.0;
scalar kNeg = Q*pow(U, 2.0)*rhoFuel/sigma;
scalar derivativePos = sqrt
(
Q*pow(U,2.0)
);
scalar derivativeNeg =
(
8.0*pow(nuFuel, 2.0)*pow(kNeg, 3.0)
+ Q*pow(U, 2.0)*kNeg
- 3.0*sigma/2.0/rhoFuel*pow(kNeg, 2.0)
)
/
sqrt
(
4.0*pow(nuFuel, 2.0)*pow(kNeg, 4.0)
+ Q*pow(U, 2.0)*pow(kNeg, 2.0)
- sigma*pow(kNeg, 3.0)/rhoFuel
)
-
4.0*nuFuel*kNeg;
scalar kOld = 0.0;
for(label i=0; i<40; i++)
{
k = kPos - (derivativePos/((derivativeNeg-derivativePos)/(kNeg-kPos)));
scalar derivativek =
(
8.0*pow(nuFuel, 2.0)*pow(k, 3.0)
+ Q*pow(U, 2.0)*k
- 3.0*sigma/2.0/rhoFuel*pow(k, 2.0)
)
/
sqrt
(
4.0*pow(nuFuel, 2.0)*pow(k, 4.0)
+ Q*pow(U, 2.0)*pow(k, 2.0)
- sigma*pow(k, 3.0)/rhoFuel
)
-
4.0*nuFuel*k;
if(derivativek > 0)
{
derivativePos = derivativek;
kPos = k;
}
else
{
derivativeNeg = derivativek;
kNeg = k;
}
if(mag(k-kOld)/k < 1e-4)
{
break;
}
kOld = k;
}
scalar omegaS =
- 2.0 * nuFuel * pow(k, 2.0)
+ sqrt
(
4.0*pow(nuFuel, 2.0)*pow(k, 4.0)
+ Q*pow(U, 2.0)*pow(k, 2.0)
- sigma*pow(k, 3.0)/rhoFuel
);
tau = cTau_/omegaS;
dL = sqrt(8.0*p.d()/k);
}
else
{
k =
rhoAverage*pow(U, 2.0)
/
2.0*sigma;
//--------------------------------------AL____101011--------------------------------//
// scalar J = pWalk*p.d()/2.0;
scalar J = time*hSheet/2.0;
//-----------------------------------------END--------------------------------------//
tau = pow(3.0*cTau_,2.0/3.0)*cbrt(J*sigma/(sqr(Q)*pow(U,4.0)*rhoFuel));
dL = sqrt(4.0*p.d()/k);
}
scalar kL =
1.0
/
(
dL *
pow(0.5 + 1.5 * muFuel/pow((rhoFuel*sigma*dL), 0.5), 0.5)
);
scalar dD = cbrt(3.0*mathematicalConstant::pi*pow(dL, 2.0)/kL);
// lisaExp is included in coeffsDict
// scalar lisaExp = 0.27;
scalar ambientPressure = 1.0e+5;
scalar pRatio = spray_.ambientPressure()/ambientPressure;
dD = dD*pow(pRatio,lisaExp_);
// modifications to take account of the flash boiling on primary breakUp
scalar pExp = 0.135;
scalar chi = 0.0;
label Nf = fuels.components().size();
scalar Td = p.T();
for(label i = 0; i < Nf ; i++)
{
if(fuels.properties()[i].pv(spray_.ambientPressure(), Td) >= 0.999*spray_.ambientPressure())
{
// The fuel is boiling.....
// Calculation of the boiling temperature
scalar tBoilingSurface = Td;
label Niter = 200;
for(label k=0; k< Niter ; k++)
{
scalar pBoil = fuels.properties()[i].pv(pressure, tBoilingSurface);
if(pBoil > pressure)
{
tBoilingSurface = tBoilingSurface - (Td-temperature)/Niter;
}
else
{
break;
}
}
scalar hl = fuels.properties()[i].hl(spray_.ambientPressure(), tBoilingSurface);
scalar iTp = fuels.properties()[i].h(spray_.ambientPressure(), Td) - spray_.ambientPressure()/fuels.properties()[i].rho(spray_.ambientPressure(), Td);
scalar iTb = fuels.properties()[i].h(spray_.ambientPressure(), tBoilingSurface) - spray_.ambientPressure()/fuels.properties()[i].rho(spray_.ambientPressure(), tBoilingSurface);
chi += p.X()[i]*(iTp-iTb)/hl;
}
}
// bounding chi
chi = max(chi, 0.0);
chi = min(chi, 1.0);
// modifing dD to take account of flash boiling
dD = dD*(1.0 - chi*pow(pRatio, -pExp));
scalar lBU = Cl_ * mag(p.U())*tau;
if(pWalk > lBU)
{
p.liquidCore() = 0.0;
// calculate the new diameter with the standard 1D Rosin Rammler distribution
//--------------------------------AL_____101012------------------------------//
// Calculation of the mean radius based on SMR rs. Coefficient factorGamma depends on nExp.
// Note that Reitz either used (Schmidt et al., 1999-01-0496) or skipped (Senecal et al.) this factor!!!
// scalar factorGamma = 0.75*sqrt(mathematicalConstant::pi); //nExp=2
scalar factorGamma = 1.;
scalar delta = dD/factorGamma;
/* dD is the SMD, and the delta is calculated using gama
function. Here we assume nExp = 2. */
// scalar delta = dD/(0.75*sqrt(mathematicalConstant::pi));
// scalar minValue = min(p.d()/20.0,dD/20.0);
scalar minValue = dD/10.0;
// delta is divided by 20 instead of 10 in order to make sure of small minValue
// scalar minValue = min(p.d(),dD/20.0);
// scalar maxValue = p.d();
scalar maxValue = dD;
// The pdf value for 4.0*delta is already very small.
// scalar maxValue = delta*4.0;
if(maxValue - minValue < SMALL)
{
// minValue = p.d()/20.0;
minValue = maxValue/20.0;
//-----------------------------------END-------------------------------------//
}
scalar range = maxValue - minValue;
scalar nExp = 3;
scalar rrd_[500];
//--------------------------------AL_____101012------------------------------//
scalar probFactorMin = exp(-pow(minValue/delta,nExp));
scalar probFactorMax = exp(-pow(maxValue/delta,nExp));
scalar probFactor = 1./(probFactorMin - probFactorMax);
//-----------------------------------END-------------------------------------//
for(label n=0; n<500; n++)
{
scalar xx = minValue + range*n/500;
//-------------------------------AL_____101012-------------------------------//
// rrd_[n] = 1 - exp(-pow(xx/delta,nExp));
rrd_[n] = (probFactorMin - exp(-pow(xx/delta,nExp)))*probFactor;
//-----------------------------------END-------------------------------------//
}
bool success = false;
scalar x = 0;
scalar y = rndGen_.scalar01();
label k = 0;
while(!success && (k<500))
{
if (rrd_[k]>y)
{
success = true;
}
k++;
}
//--------------------------------AL_____101012------------------------------//
// x = minValue + range*n/500;
x = minValue + range*(k-0.5)/500.0;
//------------------------------------END------------------------------------//
// New droplet diameter
p.d() = x;
p.ct() = 0.0;
}
}
void reitzKHRT::breakupParcel
(
parcel& p,
const scalar deltaT,
const vector& vel,
const liquidMixture& fuels
) const
{
label celli = p.cell();
scalar T = p.T();
scalar r = 0.5*p.d();
scalar pc = spray_.p()[celli];
scalar sigma = fuels.sigma(pc, T, p.X());
scalar rhoLiquid = fuels.rho(pc, T, p.X());
scalar muLiquid = fuels.mu(pc, T, p.X());
scalar rhoGas = spray_.rho()[celli];
scalar Np = p.N(rhoLiquid);
scalar semiMass = Np*pow(p.d(), 3.0);
scalar weGas = p.We(vel, rhoGas, sigma);
scalar weLiquid = p.We(vel, rhoLiquid, sigma);
// correct the Reynolds number. Reitz is using radius instead of diameter
scalar reLiquid = 0.5*p.Re(rhoLiquid, vel, muLiquid);
scalar ohnesorge = sqrt(weLiquid)/(reLiquid + VSMALL);
scalar taylor = ohnesorge*sqrt(weGas);
vector acceleration = p.Urel(vel)/p.tMom();
vector trajectory = p.U()/mag(p.U());
scalar gt = (g_ + acceleration) & trajectory;
// frequency of the fastest growing KH-wave
scalar omegaKH =
(0.34 + 0.38*pow(weGas, 1.5))
/((1 + ohnesorge)*(1 + 1.4*pow(taylor, 0.6)))
*sqrt(sigma/(rhoLiquid*pow(r, 3)));
// corresponding KH wave-length.
scalar lambdaKH =
9.02
*r
*(1.0 + 0.45*sqrt(ohnesorge))
*(1.0 + 0.4*pow(taylor, 0.7))
/pow(1.0 + 0.865*pow(weGas, 1.67), 0.6);
// characteristic Kelvin-Helmholtz breakup time
scalar tauKH = 3.726*b1_*r/(omegaKH*lambdaKH);
// stable KH diameter
scalar dc = 2.0*b0_*lambdaKH;
// the frequency of the fastest growing RT wavelength.
scalar helpVariable = mag(gt*(rhoLiquid - rhoGas));
scalar omegaRT = sqrt
(
2.0*pow(helpVariable, 1.5)
/(3.0*sqrt(3.0*sigma)*(rhoGas + rhoLiquid))
);
// RT wave number
scalar KRT = sqrt(helpVariable/(3.0*sigma + VSMALL));
// wavelength of the fastest growing RT frequency
scalar lambdaRT = 2.0*mathematicalConstant::pi*cRT_/(KRT + VSMALL);
// if lambdaRT < diameter, then RT waves are growing on the surface
// and we start to keep track of how long they have been growing
if ((p.ct() > 0) || (lambdaRT < p.d()))
{
p.ct() += deltaT;
}
// characteristic RT breakup time
scalar tauRT = cTau_/(omegaRT + VSMALL);
// check if we have RT breakup
if ((p.ct() > tauRT) && (lambdaRT < p.d()))
{
// the RT breakup creates diameter/lambdaRT new droplets
p.ct() = -GREAT;
scalar multiplier = p.d()/lambdaRT;
scalar nDrops = multiplier*Np;
p.d() = cbrt(semiMass/nDrops);
}
// otherwise check for KH breakup
else if (dc < p.d())
{
// no breakup below Weber = 12
if (weGas > weberLimit_)
{
label injector = label(p.injector());
scalar fraction = deltaT/tauKH;
// reduce the diameter according to the rate-equation
p.d() = (fraction*dc + p.d())/(1.0 + fraction);
scalar ms = rhoLiquid*Np*pow3(dc)*mathematicalConstant::pi/6.0;
p.ms() += ms;
// Total number of parcels for the whole injection event
label nParcels =
spray_.injectors()[injector].properties()->nParcelsToInject
(
spray_.injectors()[injector].properties()->tsoi(),
spray_.injectors()[injector].properties()->teoi()
);
scalar averageParcelMass =
spray_.injectors()[injector].properties()->mass()/nParcels;
if (p.ms()/averageParcelMass > msLimit_)
{
// set the initial ms value to -GREAT. This prevents
// new droplets from being formed from the child droplet
// from the KH instability
// mass of stripped child parcel
scalar mc = p.ms();
// Prevent child parcel from taking too much mass
if (mc > 0.5*p.m())
{
mc = 0.5*p.m();
}
spray_.addParticle
(
new parcel
(
spray_,
p.position(),
p.cell(),
p.n(),
dc,
p.T(),
mc,
0.0,
0.0,
0.0,
-GREAT,
p.tTurb(),
0.0,
p.injector(),
p.U(),
p.Uturb(),
p.X(),
p.fuelNames()
)
);
p.m() -= mc;
p.ms() = 0.0;
}
}
}
}