[Kummi]

Hello Foamers,
I am not sure about my approach - fitting the interface conditions through GROOVY boundary conditions.The temperature is supplied from one end of the wall. My conditions at the interface (boiling plane) are as follows

T= 100 (saturation temperature when phase change occurs)
@T=100 --> [w(moisture content)->at high (-) temperature side =0]

Based on it, mass and heat balances are calculated at interface as,

Mass balance (r) = rho * alpha * (dx/dt) [kg/m2.s] (calculated at -> low (+) temperature side)
Heat balance (-K dT/dx) = (r) * latent heat [W/m2]

PS: The interface (boiling plane) is located based on sign changes technique as xb- & xb+ where, xb = position of boiling plane. What technique should I need to adopt here? I'm confused here.
REF - Clear details here in this MANUSCRIPT ~ http://sci-hub.tw/https://doi.org/10...361(83)90225-9 Images attached with schematic model and curve.

Kindly help me. Thank you^^

[Kummi]

While browsing I have gone through the thread below: - Where my expecting equations mentioned above seems to be fitted appropriately.
Evaporation due to Heat Transport using InterFoam (Correct Implementation?)
I have manipulated this code a bit from the previous thread.
CODE:

volVectorField gradAlpha = fvc::grad(alpha1);
// to compute interface normal unit vector
volVectorField nHat = gradAlpha/(mag(gradAlpha) + interface.deltaN());
// compute interfacial area = magnitude of grad(alpha1)*volume of cell
volScalarField alpha1Prime = mag(gradAlpha);
// set liquid and interfacial temperature to Tsat
forAll(mesh.cells(), celli)
{
if (alpha1[celli] <= scalar(0.1)) //10% of moisture
{
T[celli] = Tsat.value(); //Tsat = 100deg
alpha1Prime[celli] = scalar(0); //Moisture content = 0
}
}
// Compute mass source field (mass balance)
//mDot = -(kappa/evapEnthalpy)*(fvc::grad(T) & nHat)*alpha1Prime;
mDot = -(rho*alpha1*interface_VELOCITY);

// Compute energy source field using enthalpy of evaporation (energy balance)
hDot = -evapEnthalpy*mDot;

Heat balance (flux) of boiling is expressed in unit of W/m2 ==> source term in energy equation carries the unit W/m3 ~ And I am confused here as how to implement this equation as a source term in my work?

So, should the mass and energy balance equations need to be fitted as boundary condition (or) interface condition? How and where the above set of coding can be fitted in OpenFOAM and compiled appropriately ?

ENERGY EQU: rho*Cp*(delT/delt) = del/delx[K*delT/delx ] + r*cp*delT/delx + rho*delQ/delT (W/m3)

Kindly someone share ideas please. Thank you

[Kummi]

The above coding comes under interfaceProperties (~/OpenFOAM/OpenFOAM-2.1.1/src/transportModels/interfaceProperties)

{
const fvMesh& mesh = alpha1.mesh();
const surfaceVectorField& Sf = mesh.Sf();

// Cell gradient of alpha
volVectorField gradAlpha = fvc::grad(alpha1);

// Interpolated face-gradient of alpha
surfaceVectorField gradAlphaf(fvc::interpolate(gradAlpha));

// to compute interface normal unit vector
//volVectorField nHat = gradAlpha/(mag(gradAlpha) + interface.deltaN());
// Face unit interface normal flux
// nHatf_ = nHatfv & Sf;
// Face unit interface normal
//surfaceVectorField nHatfv(gradAlphaf/(mag(gradAlphaf) + deltaN_));

// compute interfacial area = magnitude of grad(alpha1)*volume of cell
//volScalarField alpha1Prime = mag(gradAlpha);
surfaceScalarField alpha1Prime = mag(gradAlpha);

// set liquid and interfacial temperature to Tsat
forAll(mesh.cells(), celli)
{
if (alpha1[celli] <= scalar(0.1)) //10% of moisture
{
T[celli] = Tsat.value(); //Tsat = 100deg
alpha1Prime[celli] = scalar(0); //Moisture content = 0
}
}
// Compute mass source field (mass balance)
//mDot = -(kappa/evapEnthalpy)*(fvc::grad(T) & nHat)*alpha1Prime;
mDot = -(rho*alpha1*interface_VELOCITY);

// Compute energy source field using enthalpy of evaporation (energy balance)
hDot = -evapEnthalpy*mDot;

No calculation related to contact angle here.


The above code is not compiled yet, but it should be calculated for mass and energy balance at the interface --> moisture evaporation from the wet COAL

I should still explore more for the betterment of my solution.