Dual stream heat exchanger for porous media
This commit is contained in:
Hrvoje Jasak
parent
baabe4700b
commit
6c3a4880a4
4 changed files with 185 additions and 116 deletions
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@ -77,16 +77,18 @@ Foam::porousZone::porousZone
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C1_(0),
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D_("D", dimensionSet(0, -2, 0, 0, 0), tensor::zero),
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F_("F", dimensionSet(0, -1, 0, 0, 0), tensor::zero),
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rhoPri_(0),
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Cpri_(0),
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Maux_(0),
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Qaux_(0),
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Caux_(0),
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Taux_(0),
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caux_(0),
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Qepsilon_(0),
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Tauxrelax_(0),
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TauxRelax_(1),
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nCellsAuxInlet_(0),
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firstCell_(0),
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auxUnitVector_(vector::zero),
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nVerticalCells_(0)
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{
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Info<< "Creating porous zone: " << name_ << endl;
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@ -184,7 +186,7 @@ Foam::porousZone::porousZone
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// provide some feedback for the user
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// writeDict(Info, false);
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// it is an error not to define anything
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// It is an error not to define anything
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if
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(
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C0_ <= VSMALL
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@ -206,32 +208,41 @@ Foam::porousZone::porousZone
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if (const dictionary* dictPtr = dict_.subDictPtr("heatTransfer"))
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{
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Info<< "Reading porous heatTransfer: Maux and Taux" << nl;
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dictPtr->lookup("rhoPri") >> rhoPri_;
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dictPtr->lookup("Cpri") >> Cpri_;
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dictPtr->lookup("Maux") >> Maux_;
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dictPtr->lookup("Qaux") >> Qaux_;
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dictPtr->lookup("Caux") >> Caux_;
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dictPtr->lookup("Taux") >> Taux_;
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dictPtr->lookup("caux") >> caux_;
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dictPtr->lookup("Qepsilon") >> Qepsilon_;
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dictPtr->lookup("firstCell") >> firstCell_;
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dictPtr->lookup("auxUnitVector") >> auxUnitVector_;
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dictPtr->lookup("nVerticalCells") >> nVerticalCells_;
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dictPtr->lookup("nCellsAuxInlet") >> nCellsAuxInlet_;
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dictPtr->lookup("TauxRelax") >> Tauxrelax_;
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Info<< "Maux = " << Maux_ <<
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", Taux = " << Taux_ <<
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", caux = " << caux_ <<
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", nCellsAuxInlet = " << nCellsAuxInlet_ <<
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", Qepsilon = " << Qepsilon_ << nl;
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dictPtr->lookup("TauxRelax") >> TauxRelax_;
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Info<< "Maux = " << Maux_
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<< ", Taux = " << Taux_
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<< ", Caux = " << Caux_
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<< ", nCellsAuxInlet = " << nCellsAuxInlet_
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<< ", Qepsilon = " << Qepsilon_
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<< endl;
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if (mag(auxUnitVector_) < SMALL)
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{
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FatalIOErrorInFunction(dict)
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<< "auxUnitVector for heat transfer zone "
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<< name_ << " has zero length"
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<< exit(FatalIOError);
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}
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else
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{
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FatalIOErrorIn
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(
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"Foam::porousZone::porousZone"
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"(const fvMesh&, const word&, const dictionary&)",
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dict_
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) << "\"heatTransfer\" dictionary not specified"
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<< exit(FatalIOError);
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auxUnitVector_ /= mag(auxUnitVector_);
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}
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}
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}
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@ -330,6 +341,7 @@ void Foam::porousZone::addResistance
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}
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bool compressible = false;
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if (UEqn.dimensions() == dimensionSet(1, 1, -2, 0, 0))
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{
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compressible = true;
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@ -473,35 +485,60 @@ void Foam::porousZone::macroCellOrder
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Info<< "Creating cellsOrdered list for porous heat transfer zone "
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<< name_ << nl << endl;
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const labelList& cells = mesh_.cellZones()[cellZoneID_];
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const vectorField& cellsCellCenter = mesh_.cellCentres();
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// Get current zone
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const cellZone& curZone = mesh_.cellZones()[cellZoneID_];
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// Get cell centres
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const vectorField& cellCentres = mesh_.C().internalField();
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// Get cell-cell addressing
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const labelListList& cc = mesh_.cellCells();
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scalarField& Tauxi = Taux.internalField();
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label nCellsAuxInlet(nCellsAuxInlet_);
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label firstCell(firstCell_);
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label nVerticalCells(nVerticalCells_);
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vector auxUnitVector(auxUnitVector_);
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// Get inlet cells
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labelList cellsAuxInlet(nCellsAuxInlet_, -1);
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labelList cellsAuxInlet(nCellsAuxInlet, -1);
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cellsAuxInlet[0] = firstCell;
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if (nCellsAuxInlet_ > 0)
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{
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cellsAuxInlet[0] = firstCell_;
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}
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else
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{
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WarningInFunction
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<< "Number of aux inlet cells is set to zero: " << nCellsAuxInlet_
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<< "Reconsider the definition of macro cell order"
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<< endl;
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}
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// Creating horizontal list of cells, cellsAuxInlet[nCellsAuxInlet_]
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label newCounter = 1;
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// Note
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// Terrible search algorithms
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// Will work only in serial. Rewrite required
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// HJ, 17/Jul/2019
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// - Creating horizontal list of cells, cellsAuxInlet[nCellsAuxInlet]
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label newcounter = 1;
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forAll (cellsAuxInlet, i)
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{
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const labelList& cellNb = mesh_.cellCells(cellsAuxInlet[i]);
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const labelList& cellNb = cc[cellsAuxInlet[i]];
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forAll (cellNb, ii)
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{
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bool isInsideNb = false;
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forAll (cellsAuxInlet, iii)
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{
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if (cellNb[ii] == cellsAuxInlet[iii]) isInsideNb = true;
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if (cellNb[ii] == cellsAuxInlet[iii])
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{
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isInsideNb = true;
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break;
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}
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}
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if (!isInsideNb)
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{
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if (mesh_.cellZones()[cellZoneID_].whichCell(cellNb[ii]) != -1)
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if (curZone.whichCell(cellNb[ii]) != -1)
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{
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if
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(
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@ -509,21 +546,21 @@ void Foam::porousZone::macroCellOrder
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(
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(
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(
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cellsCellCenter[cellsAuxInlet[i]]
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- cellsCellCenter[cellNb[ii]]
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cellCentres[cellsAuxInlet[i]]
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- cellCentres[cellNb[ii]]
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)/
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mag
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(
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cellsCellCenter[cellsAuxInlet[i]]
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- cellsCellCenter[cellNb[ii]]
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cellCentres[cellsAuxInlet[i]]
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- cellCentres[cellNb[ii]]
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)
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)
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& auxUnitVector
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& auxUnitVector_
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) < 0.5
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)
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{
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cellsAuxInlet[newcounter] = cellNb[ii];
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++newcounter;
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cellsAuxInlet[newCounter] = cellNb[ii];
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++newCounter;
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}
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}
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}
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@ -532,42 +569,45 @@ void Foam::porousZone::macroCellOrder
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scalarField& Macroi = Macro.internalField();
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labelList cellsOrdered(cells.size(), -1);
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labelList cellsOrdered(curZone.size(), -1);
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// Writing horizontal cells into list cellsOrdered[cells.size()]
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forAll (cellsAuxInlet, i)
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{
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cellsOrdered[i*nVerticalCells] = cellsAuxInlet[i];
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cellsOrdered[i*nVerticalCells_] = cellsAuxInlet[i];
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}
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// Creating cellsOrdered list of ordered horizontal cells
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label counter = 1;
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forAll (cellsOrdered, i)
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{
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Macroi[cellsOrdered[i]] = i;
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Tauxi[cellsOrdered[i]] = Taux_;
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if ((i > 1) && (i % nVerticalCells == 0))
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if ((i > 1) && (i % nVerticalCells_ == 0))
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{
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++counter;
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}
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const labelList& cellNb = mesh_.cellCells(cellsOrdered[i]);
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const labelList& cellNb =cc[cellsOrdered[i]];
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forAll (cellNb, iii)
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{
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bool isInsideNb = false;
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forAll (cellsOrdered, iiii)
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{
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if (cellNb[iii] == cellsOrdered[iiii])
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{
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isInsideNb = true;
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break;
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}
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}
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if (!isInsideNb)
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{
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if (mesh_.cellZones()[cellZoneID_].whichCell(cellNb[iii]) != -1)
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if (curZone.whichCell(cellNb[iii]) != -1)
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{
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if
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(
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@ -575,16 +615,16 @@ void Foam::porousZone::macroCellOrder
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(
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(
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(
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cellsCellCenter[cellsOrdered[i]]
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- cellsCellCenter[cellNb[iii]]
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cellCentres[cellsOrdered[i]]
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- cellCentres[cellNb[iii]]
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)/
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mag
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(
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cellsCellCenter[cellsOrdered[i]]
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- cellsCellCenter[cellNb[iii]]
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cellCentres[cellsOrdered[i]]
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- cellCentres[cellNb[iii]]
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)
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)
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& auxUnitVector
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& auxUnitVector_
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) > 0.85
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)
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{
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@ -602,9 +642,11 @@ void Foam::porousZone::macroCellOrder
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forAll (cellsOrdered, i)
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{
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const labelList& cellFaces = mesh_.cells()[cellsOrdered[i]];
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forAll (cellFaces,ii)
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forAll (cellFaces, ii)
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{
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label faceI = cellFaces[ii];
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if (mesh_.isInternalFace(faceI))
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{
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if (mesh_.faceOwner()[faceI] == cellsOrdered[i])
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@ -626,15 +668,10 @@ void Foam::porousZone::macroCellOrder
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else
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{
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const label patchI = mesh_.boundaryMesh().whichPatch(faceI);
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const label faceIL =
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mesh_.boundaryMesh()[patchI].whichFace(faceI);
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if (patchI < 0)
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{
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Info << "patchI < 0 " << endl;
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return;
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}
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if (phi.boundaryField()[patchI][faceIL] > 0.0)
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{
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posFluxi[cellsOrdered[i]] +=
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@ -645,6 +682,7 @@ void Foam::porousZone::macroCellOrder
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}
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}
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void Foam::porousZone::writeDict(Ostream& os, bool subDict) const
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{
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if (subDict)
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@ -39,13 +39,15 @@ Description
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S = - \rho C_0 |U|^{(C_1 - 1)/2} U
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@f]
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In the porous zone a heat source using the single stream heat exchanger
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In the porous zone a heat source using the dual stream heat exchanger
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approach:
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heatTransfer
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@f[
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Qtot = const //[J/s]
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Tref = const //[K]
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Maux = Mass flow of aux fluid // [kg/s]
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Qaux = Heat to be eliminated // [W]
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Caux = Specific heat capacity of aux fluid // [J / kg K]
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Taux = initial guess for aux fluid inlet temperature // [K]
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@f]
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Darcy-Forchheimer (@e d and @e f parameters)
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@ -138,20 +140,29 @@ class porousZone
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//- Forchheimer coefficient
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dimensionedTensor F_;
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//- Density of primary fluid
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scalar rhoPri_;
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//- Specific heat capacity of primary fluid
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scalar Cpri_;
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//- Mass flow of aux fluid
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scalar Maux_;
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//- Inlet temperature of aux fluid
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scalar Taux_;
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//- Heat to be eliminated
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scalar Qaux_;
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//- Specific heat capacity of coolant
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scalar caux_;
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scalar Caux_;
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//- Inlet temperature of aux fluid
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mutable scalar Taux_;
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//- Epsilon for Single Effectiveness HX
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scalar Qepsilon_;
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//- Relaxation factor for Taux
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scalar Tauxrelax_;
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scalar TauxRelax_;
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// Geometrical description of the porous heat exchanger
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@ -33,12 +33,12 @@ void Foam::porousZone::modifyDdt(fvMatrix<Type>& m) const
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{
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if (porosity_ < 1)
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{
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const labelList& cells = mesh_.cellZones()[cellZoneID_];
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const labelList& zoneCells = mesh_.cellZones()[cellZoneID_];
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forAll(cells, i)
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forAll (zoneCells, i)
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{
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m.diag()[cells[i]] *= porosity_;
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m.source()[cells[i]] *= porosity_;
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m.diag()[zoneCells[i]] *= porosity_;
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m.source()[zoneCells[i]] *= porosity_;
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}
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}
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}
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@ -150,68 +150,86 @@ void Foam::porousZone::addHeatSource
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const scalarField dT = Tauxi - T;
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const label nMacro(nCellsAuxInlet_*nVerticalCells_);
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scalarList Tmacro(nMacro, 0.0);
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scalarList dTaux(nMacro, 0.0);
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scalar QSum(0.0);
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scalarField Tmacro(nMacro, scalar(0));
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scalarField dTaux(nMacro, scalar(0));
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scalar QSum = 0;
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const scalar Taux_relax(Tauxrelax_);
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const scalar c_aux(caux_);
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const scalar c_pri(1009.0);
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const scalar qm_aux(Maux_);
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const scalar qm_auxi = qm_aux/nCellsAuxInlet_;
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const scalar T_aux(Taux_);
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const scalar rho_pri(1.1021);
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const scalar Qeps(Qepsilon_);
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// Mass flow rate for individual channels
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const scalar qmAuxi = Maux_/nCellsAuxInlet_;
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const labelList& cells = mesh_.cellZones()[cellZoneID_];
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// Get zone cells
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const labelList& zoneCells = mesh_.cellZones()[cellZoneID_];
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forAll(cells, i)
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forAll (zoneCells, i)
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{
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scalar Qcell = Qeps*rho_pri*c_pri*posFlux[cells[i]]*dT[cells[i]];
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scalar Qcell =
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Qepsilon_*rhoPri_*Cpri_*posFlux[zoneCells[i]]*dT[zoneCells[i]];
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// heat in each macro(cell)
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Qauxi[cells[i]] = Qcell;
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// Heat in each macro (cell)
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Qauxi[zoneCells[i]] = Qcell;
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// make an int out of a macro
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const int macro = Macro[cells[i]];
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const int macro = Macro[zoneCells[i]];
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// deltaTaux in each macro(cell)
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dTaux[macro] = Qcell/(c_aux*qm_auxi);
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dTaux[macro] = Qcell/(Caux_*qmAuxi);
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// adding Heat to equation
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QSource[cells[i]] += Qcell/(rho_pri*c_pri);
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QSource[zoneCells[i]] += Qcell/(rhoPri_*Cpri_);
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// summing for total heat of HX
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QSum += Qcell;
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}
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reduce(dTaux, sumOp<scalarList>());
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Tmacro[0] = T_aux;
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reduce(dTaux, sumOp<scalarField>());
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Tmacro[0] = Taux_;
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forAll (Tmacro, i)
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{
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if (i > 0)
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{
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Tmacro[i] = Tmacro[i-1] - dTaux[i-1];
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}
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if ((i > 0) && (i % nVerticalCells_ == 0))
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if (i % nVerticalCells_ == 0)
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{
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Tmacro[i] = T_aux;
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Tmacro[i] = Taux_;
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}
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else
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{
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Tmacro[i] = Tmacro[i - 1] - dTaux[i - 1];
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}
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}
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}
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reduce(QSum, sumOp<scalar>());
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Info << "Heat exchanger: " << name_ << endl;
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Info << "Q = " << QSum << endl;
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Info << "deltaT = " << QSum/(qm_aux*c_aux) << endl;
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forAll(cells, i)
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// Adjust Taux_ to match the specified transferred heat
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scalar deltaTAux = (Qaux_ - QSum)/(Maux_*Caux_);
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Info<< "Heat exchanger: " << name_
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<< ": Q = " << QSum
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<< " Taux = " << Taux_
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<< " delta Taux = " << deltaTAux
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<< endl;
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// Relax the heat source
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forAll (zoneCells, i)
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{
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const int macro = Macro[cells[i]];
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Tauxi[cells[i]] = Tauxi_old[cells[i]]
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// upwind scheme for Aux fluid (Tmacro = inlet temp)
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+ Taux_relax*(Tmacro[macro] - Tauxi_old[cells[i]]);
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const int macro = Macro[zoneCells[i]];
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Tauxi[zoneCells[i]] = Tauxi_old[zoneCells[i]]
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+ TauxRelax_*(Tmacro[macro] - Tauxi_old[zoneCells[i]]);
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}
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// Note: need better relaxation to speed up convergence close
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// to the matching value, when deltaTAux -> 0
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// HJ, 17/Jul/2019
|
||||
|
||||
// Limit deltaTAux to 10% of Taux_
|
||||
deltaTAux = sign(deltaTAux)*Foam::min(0.1*Taux_, mag(deltaTAux));
|
||||
|
||||
// Update Taux for next iteration
|
||||
Taux_ += TauxRelax_*deltaTAux;
|
||||
}
|
||||
|
||||
|
||||
|
|
|
|||
|
|
@ -47,8 +47,10 @@ Description
|
|||
}
|
||||
heatTransfer
|
||||
{
|
||||
Qtot 50; //[J/s]
|
||||
Tref 273.15; //[K]
|
||||
Maux = Mass flow of aux fluid // [kg/s]
|
||||
Qaux = Heat to be eliminated // [W]
|
||||
Caux = Specific heat capacity of aux fluid // [J / kg K]
|
||||
Taux = initial guess for aux fluid inlet temperature // [K]
|
||||
}
|
||||
}
|
||||
)
|
||||
|
|
@ -168,7 +170,7 @@ public:
|
|||
const volScalarField& posFlux
|
||||
) const;
|
||||
|
||||
//- Order cells for Dual Stream model
|
||||
//- Order cells for the Dual Stream model
|
||||
void macroCellOrder
|
||||
(
|
||||
volScalarField& Taux,
|
||||
|
|
|
|||
Reference in a new issue