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August 26, 2016, 06:19 |
LiquidEvaporationBoil & LiquidEvaporation
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#1 |
New Member
Amir
Join Date: Feb 2012
Posts: 12
Rep Power: 14 |
Hi,
I'm running a test case with sprayFoam. I have used two evaporation models "LiquidEvaporationBoil" and "LiquidEvaporation". The results are different. After some investigations, I figured out, if boiling does not occurs, theoretically two models should behave the same. dMassPC[lid] in LiquidEvaporation is clear Code:
dMassPC[lid] +=kc*(Cs - Cinf) *pi*sqr(d)*liquids_.properties()[lid].W()*dt However I can not understand how dMassPC[lid] is calculated in LiquidEvaporationBoil (when there is not boiling) Code:
else { // evaporation // surface molar fraction - Raoult's Law const scalar Xs = X[lid]*pSat/pc; // molar ratio const scalar Xr = (Xs - Xc)/max(SMALL, 1.0 - Xs); if (Xr > 0) { // mass transfer [kg] dMassPC[lid] += pi*d*Sh*Dab*rhos*log(1.0 + Xr)*dt; } } |
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August 26, 2016, 08:22 |
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#2 |
New Member
Amir
Join Date: Feb 2012
Posts: 12
Rep Power: 14 |
I found some information baout the evaporation part in the "LiquidEvaporationBoil" model. It is called "The Spalding evaporation model" (Spalding (1953)). you can find more information in the following link
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July 31, 2019, 06:03 |
Spalding number in LiquidEvaporationBoil
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#3 |
New Member
Alessandro
Join Date: Jul 2016
Posts: 11
Rep Power: 10 |
I know the post is quite old but I have a question concerning the use of Xr in the expression:
dMassPC[lid] += pi*d*Sh*Dab*rhos*log(1.0 + Xr)*dt; In literature this expression is always written using Bm, the Spalding mass number: #mass ratio const scalar Bm=(Ys-Yc)/max(SMALL,1.0-Ys) #Molar ratio const scalar Xr = (Xs - Xc)/max(SMALL, 1.0 - Xs) Does anybody know the rationale behind this choice in OpenFOAM? |
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