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How to model 1 phase STEFAN problem - Explicit FREE boundary condition |
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July 28, 2019, 04:33 |
How to model 1 phase STEFAN problem - Explicit FREE boundary condition
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#1 | |
Senior Member
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Dear Foamers, Help me out here. Attachment gives clear overview. Hereby explaining the gist of my problem. In my work, boiling is considered as a point sink of moisture calculated based on mass and energy balances.
(i) I would like to know as how to implement the Stefan condition (Rankine-Hugoniot condition) based on heat balance (Equ: 10) for moisture in OpenFOAM? Quote:
ENERGY EQU: rho*Cp*(delT/delt) = del/delx[K*delT/delx ] + r_gas*c_gas*delT/delx + rho*delQ/delT (W/m3) (ii) The interface (boiling plane) is located based on sign changes technique as xb- & xb+ where, xb = position of boiling plane. Should I need to adopt level set method ? I'm confused here. REF - Clear details here in this MANUSCRIPT ~ https://sci-hub.tw/https://doi.org/1...361(83)90225-9 Kindly share some advisable methodology in OpenFOAM. Thank you Foamers !! |
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July 29, 2019, 01:16 |
Temperature jump based on heat balance
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#2 |
Senior Member
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Some additional info:
The heat balance equation mentioned above serve as Rankine-Hugoniot ‘‘shock’’ condition which indicates ‘‘interface jump’’ condition expressing energy conservation. At T = 100 ==> the energy undergoes a jump of magnitude based on heat balance term. Figure attached ==> shows how jump occurs during phase transition. ~ No separate transport equations for phase change phenomenon. Phenomenon ==> when the wet coal is heated up, initially a part of heat is needed for the phase change of the water: so should consider this in the energy equation of the pyrolisis model maybe as additional source term - (r*Cp*delT/Delx) - r= rate of evaporation calculated based on mass balance (based on temperature only) stated above. Someone throw light upon this problem please. Some guiding steps in OpenFOAM..?? Thank you !! |
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July 30, 2019, 01:56 |
Energy balance across the liquid-gas interface
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#3 | ||
Senior Member
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Quote:
Quote:
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July 30, 2019, 21:51 |
Evaporation condition for liquid-vapor interface
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#4 | |
Senior Member
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(i) As seen in the attached image, inside the chamber the energy equation follows, which contains the source term for evaporation as "TEMPERATURE CONVECTION" - there is no velocity and pressure in my case.
(ii) Near the interface [location (2)], by default I have prescribed the condition as "compressible::turbulenttemperatureCoupledBaffleMix ed". But I require "EVAPORATION INTERFACE CONDITION" Quote:
Please read my above conditions and correct me if I understood something wrong. 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. On the whole, I am in need of evaporation boundary condition at the interface. Although I gone through many cases related to this study, unfortunately I'm out of ideas as how to overcome this problem. I would real appreciate if anyone could give me a hint where to look at or point me about the implementation in OpenFOAM. Thank you Foamers. |
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