- **OpenFOAM Running, Solving & CFD**
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- - **Buoyancy of the buoyantFOAM case**
(*http://www.cfd-online.com/Forums/openfoam-solving/59701-buoyancy-buoyantfoam-case.html*)

Hi friends,
I want to use tHi friends,
I want to use the buoyantFOAM model to simulate the CO2 sequestration. But I have questions on it. Firstly, the buoyantFOAM case is driven by buoyancy. I want to control the effect of this buoyancy such as decreasing or increasing. But I really do not know where and how to do this. Also, in this model, I found maybe state equation was solved. But I can not find the variable T in source code. Secondely, I want to modify this model as the density-driven flow in porous media. So the Darcy`s law will be considered. Since the P (pressure) is solved by PISO algorithm. The problem is whether any state or energy equation will be added to buoyancyFOAM case for P? Could any friend give me advice? Thanks in advance. |

The energy equation, "hEqn.H",The energy equation, "hEqn.H", is solved in terms of the internal enthalpy, "h". The temperature and several other derived thermodynamic quanties are calculated(updated) using "thermo->correct()". You can get access to the temperature using "thermo->T()". There are also two densities. The first, "rho" which is initialized in "createFields.H", and a second, calculated by thermodynamic class, "thermo->rho()". "rho" is initially calculated from mass conservation ("rhoEqn.H"). The weighted difference between the two is the continuity error.("compressibleContinuityErrors.H")
The gravity vector can be adjusted in: "<case>/constant/environmentalProperties" The "reactingFoam" application provides an example of using FOAM for multispecies flow calculations. good luck Dave |

Hi Dave:
Thank you very mucHi Dave:
Thank you very much. I will follow you to try. Also, if I want to change the propersties of the room, which is air, As you said, maybe I should change this air to coal. How should I do? Also, Could you please give help to explain the fields of "<case>/constant/thermophysicalProperties" ? Thanks again. |

Hi Guoxiang!
When I think oHi Guoxiang!
When I think of coal, I think of black solid stuff that I buy in shops for barbecues or for ovens. I don't think that the assumptions made by the buoyantFoam (density changes due to temperature changes are important) are valid for that stuff. At least not on planet earth. From your postings above I assume that you are talking about a mixture of air and CO2. I think that buoyantFoam is only applicable if that mixture is homogenous. Anyway: thermophysicalProperties is explained in chapter 8.1 of the user guide (it's not a long read, but very interesting). Should you have more specific questions after reading that chapter, I'm sure they will be answered here. |

Hi Bernhard Gschaider,
AnywHi Bernhard Gschaider,
Anyway, many thanks for your advice. Actually, I want to modify buoyantFOAM to simulate CO2 sequestration. It means that I want to injection CO2 to coal Basin. Here, CO2 is the fluid flow but coal as the fixed media for CO2 concentration. Of course, this should be the porous flow with the CO2 concentration. For now, I am thinking to develop a solve for this CO2 sequestration based on the buoyantFOAM or others. So I asked these questions which I am interested in. Whatever, I also want to get your any more advice about this. Thanks a lot. |

Hi Guoxiang!
I don't think Hi Guoxiang!
I don't think that the buoyantFoam-solver is applicable for your problem at all. If I understand your problem correctly you'll want something like the twoLiquidMixingFoam (liquids are CO2 and air) extended to support porous Media (or with Navier removed and only Darcy). |

Hi Bernhard Gschaider,
ManHi Bernhard Gschaider,
Many thanks for your advice. I will dig continuly. Best regards. |

Hi All,
I wonder if anybodyHi All,
I wonder if anybody has some written report or paper that discuss the compressible formulation used in buoyantFoam. Sorry for any inconvenience, but I only have experience with incompressible formulation. I want to shift to buoyantFoam so I can avoid the Boussinesq approx. I just need any doc that may help me derive the formulation my self so, I can modify the solver comfortably. best regards, Maka. |

Hi Maka Mohu,
I have a attaHi Maka Mohu,
I have a attachement here. But I am not sure what it is you said. The link is: hal.iwr.uni-heidelberg.de/~peter/Papers/habil.pdf |

Hi Guoxiang,
I checked the Hi Guoxiang,
I checked the report on the descriped link. Thanks for the report. It includes lots of nice information about software development issues of unstructured solvers, but it seems to be targeted for multiphase formulation and I work with single phase. I posted my message here since the title of the thread was relevant and you were asking about the formulation of buoyantFoam. What I needed is a reference that derives the formulation that is used in buoyantFoam. It is a compressible formulation that still uses a Poisson's equation for pressure. I'm also curios about the advantages, such formulation may have over the common compressible formulation where there is no Passion's equation for pressure. Thanks for you kind response. best regards, Maka |

Hi,
I met the error when IHi,
I met the error when I run buoyantFoam case: -------------------------------------------------- --> FOAM FATAL ERROR : Maximum number of iterations exceeded From function specieThermo<thermo>::T(scalar f, scalar T0, scalar (specieThermo<thermo>::*F)(const scalar) const, scalar (specieThermo<thermo>::*dFdT)(const scalar) const) const in file /home/dm2/henry/OpenFOAM/OpenFOAM-1.3/src/thermophysicalModels/specie/lnInclude/ specieThermoI.H at line 83. FOAM aborting Foam::error::printStack(Foam:: Ostream&) Foam::error::abort() Foam::hThermo<foam::puremixture<foam::consttranspo rt<foam::speciethermo<foam::hc onstthermo<foam::perfectgas> > > > >::calculate() Foam::hThermo<foam::puremixture<foam::consttranspo rt<foam::speciethermo<foam::hc onstthermo<foam::perfectgas> > > > >::correct() buoyantFoam [0x418c59] __libc_start_main __gxx_personality_v0 ------------------------------------------------ I'm using this case for Argon gas with teperature from 300 K upto 20 000K: -------------------------------------- Name Argon -------------------------------------- nMoles 1.0 molecularWeight 39.948 deltaH 1.0499e+05 viscosity 3.4079e-5 Pr 0.65 --------------------------------------- Thanks so much, Rita |

Hi,
I am using buoyancyFoaHi,
I am using buoyancyFoam case. In the thermophysical properties I need to make some changes. Originaly OpenFOAM is using : hThermo > pureMixture > constThermo > specieThermo > hConstThermo > perfectGas In my case : 1. instead constThermo I should put sutherlandTransport library 2. instead hConstThermo I should put JanafThermo. My question is how can I do the link between libraries in OpenFOAM? Thank you for your help, Rita |

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