You must either move the
g
You must either move the
g*alpha*(T-TRef) term into the UEqn construction statement fvVectorMatrix UEqn ... or also include the term in the flux prediction by including it in U = UEqn.H()/A; and remove it from the momentum correction statement U -= fvc::grad(p)/A + (g*alpha*(T-TRef))/A; |
Christian, have you had any lu
Christian, have you had any luck? I have been thinking about a boussinesq solver, but haven't had enough time to write it. Does yours work and if so, what tricks did you use to get it up and running. Thanks
|
Hi,
we also want to build a
Hi,
we also want to build a boussinesq-approximation. You wrote your solver in the version 1.2. Am I right? We changed your idea, so it could work in 1.3. But we had a problem with the line: g*alpha*(T-TRef) what type is TRef and T and where you definded it? Thanks Martin |
Hi,
also trying to get an i
Hi,
also trying to get an incompressible boussinesq-approx. solver running ... I got something working, basically what Christian has posted, with the corrections by Henry. Works mostly, but sometimes I get problems at boundaries (using a zeroGradient B.C. for pressure) I thought I needed a pressure boundary condition, and implemented one similar to the existing wallBuoyantPressure - just computing the pressure gradient as g*beta*(T-TRef) Also at first glance seemed to work, gives a smooth looking pressure field, but then I realized strange vectors and pressures at the pressure reference cell, finally calculations diverge. Fixing pressure at some boundary, instead of using pEqn.setReference(pRefCell, pRefValue), works. Not setting a pressure reference the pressure solver (AMG or ICCG) diverges. almost forgot - using OpenFOAM 1.3 Any hint would be greatly appreciated... Thank you ! Thomas |
For the lazy ones out there, I
For the lazy ones out there, I have written a Boussinesq approximation incompressible buoyant flow solver with constant material properties. You can get it from the link below, including a tutorial case:
boussinesqBuoyantFoam Currently, it is laminar and quite easy to understand, it will swallow the wall bouyant pressure b.c. and I think it's a pretty decent example. Extensions to turbulent, real material properties etc are straightforward but uninteresting (for me!). Enjoy, Hrv |
This link is dead.
This link is dead.
|
Stupid, sorry: boussinesqBuoya
|
Hrvoje,
From one of the laz
Hrvoje,
From one of the lazy ones: Your implementation suffers the same problems (mass conservation fluxes at walls not parallel to gravity and not at reference temperature). You can see it if you make your cavity hot at bottom, cold on top, and adiabatic sidewalls. A pressure B.C. computing pressure gradient as g*beta*(T-TRef), but without contribution to mass fluxes, works. There is also no need to have an extra density field - which for me is the main point of the Boussinesq approximation. regards, Thomas |
Hrvoje,
we tried to get your
Hrvoje,
we tried to get your Boussinesq approximation incompressible buoyant flow solver, but we get the following message The page cannot be found We wait your help... Sonia |
Sorry, probably got deleted: t
Sorry, probably got deleted: try it from SVN:
http://openfoam-extend.svn.sourceforge.net/viewvc/openfoam-extend/trunk/Core/Ope nFOAM-1.4.1-dev/applications/solvers/heatTransfer/boussinesqBuoyantFoam/ Hrv |
Hi,Hrvoje
Thank you for your
Hi,Hrvoje
Thank you for your help, We can download your files. We start working on this case. Sonia |
Hi,
somebody created a bous
Hi,
somebody created a boussinesq approximation solver with turbulent already and can share it with me? Thanks a lot. Bye |
Yes: have a look at:
http:/
|
Hi Hrvoje,
this solver is f
Hi Hrvoje,
this solver is for buoyancy-driven laminar flow. I like to try the boussinesq approximation with turbulent flow. thanks |
Hi Thomas,
I just wrote Wik
Hi Thomas,
I just wrote Wiki page of Boussinesq-Approximation solver for turbulent flow. http://openfoamwiki.net/index.php/Co...yantSimpleFoam Also I wrote Wiki page of tutorial case using this solver. http://openfoamwiki.net/index.php/Ma...onditionedRoom Bye! Masashi |
Hi Masashi,
thanks a lot! A
Hi Masashi,
thanks a lot! Arigato Bye |
Hi Masashi,
nice work! I like
Hi Masashi,
nice work! I like your tutorial with the makefile and the python meshing :-) Fabian |
Hi Masashi,
I have a quest
Hi Masashi,
I have a question about your implementation of the temperature equation. As I get it, you add a defined heat flux to the equation, which is activated by the internal field of Q!? I tried a more general approach by defining a heat flux b.c. using: const boussinesq::RASModel& RAS = db().lookupObject<boussinesq::rasmodel>("RASProper ties"); scalarField nuEffWall = RAS.nuEff()().boundaryField()[patch().patch().index()]; scalarField alphaEffWall = nuEffWall /Prt; gradient()=(heatFlux_/(Cp0*rho0*alphaEffWall)); Based on your added b.c. one could use: wall { type fixedHeatFlux; heatFlux 5.0; gradient uniform 200; } Though I am not sure yet, how to validate this b.c. with a really simple setup!? And right now, it is a static Prt, Cp0 and rho implementation. Does anyone know, how to get those value by a dictionary? I got one more question about the wall function. Is it correct, that as long as one uses a constant Pr model is used, the wall effects are all included in the turbulence model and no separate treatment for the temperature near-wall behavior is needed? Fabian |
Hi Fabian,
It seems that f
Hi Fabian,
It seems that fixedHeatFluxFvPatchScalarField.[C,H] are not attached properly in your previous post. So please attach them again! Masashi |
oh
http://www.cfd-online.c
|
Hi Fabian,
Thank you for at
Hi Fabian,
Thank you for attaching your code again. As a matter of fact I have made fixed heat flux B.C. library like you have made, but I intentionally remove heat flux B.C from the airConditionedRoom tutorial case in order to decrease installation process like compiling addtional custom library. However the fixed flux B.C. is more general and elegant in this tutorial indeed, so I wrote a Wiki page of my fixed heat flux B.C. library and added an option to use heat flux B.C. into airConditionedRoom tutorial case. http://openfoamwiki.net/index.php/Contrib_wallHeatFlux http://openfoamwiki.net/index.php/Ma...onditionedRoom Please have a look at Wiki pages and source code for detail. The Last question about the wall function: The separate treatment for temperature might be needed indeed, but currently I have no plan to implement them soon... So I wish someone get started on them... http://www.cfd-online.com/OpenFOAM_D...part/happy.gif Masashi |
Nice :-) Do you have a hint, a
Nice :-) Do you have a hint, about implementing it?
|
... I mean the wall treatment.
... I mean the wall treatment.
|
In the code by Masashi, the wa
In the code by Masashi, the wall heat transfer is calculated as:
temperature gradient = q/(alpha_eff*Cp0*rho0) Cp will not vary much with temperature, but density will change more than negligable for my case. What do you think, wouldn't it be better to express rho in terms of rho0, beta, g, T and T0 (Boussinesq approximation)? Hope to have someones opinion. Regards, Christian Lindbäck |
Hi to all
What is beta here
Hi to all
What is beta here? can anyone tell me? Emo |
Beta is the thermal expansion
Beta is the thermal expansion coefficient.
http://web.njit.edu/topics/Prog_Lang_Docs/html/FLUENT/fluent/fluent5/ug/html/nod e296.htm |
Hi Jeong
Thanks for the qui
Hi Jeong
Thanks for the quick answer... but i could not open your site...is it without dimension or? thanks in advance!! |
Dear Emilian,
The dimensio
Dear Emilian,
The dimension is [1/K]. You can check its dimension and value in the "/constant/transportProperties" file of the example directory. http://www.engineeringtoolbox.com/ai...ies-d_156.html http://en.wikipedia.org/wiki/Coeffic...rmal_expansion Jeong |
Dear Hrvoje,
is the Boussin
Dear Hrvoje,
is the Boussinesq approximation solver /OpenFOAM-1.4.1-dev/applications/solvers/heatTransfer/boussinesqBuoyantFoam/ compatible with OpenFOAM-1.5? If not what modifications it request? Nicoleta |
I think it will work with no c
I think it will work with no changes - try to compile and see what happens.
There sound le no problems. Enjoy. Hrv |
boussinesq approximation
Hi,
I am new to OpenFoam. I'd like to solve the problem of natural convection heat transfer in rod bundle that generating 200 kW of power. Is the boussinesq approximation solver enough for this case, since there will be two phase flow when boiling happen? bintoro |
hello Masashi,
I am trying to solve solidification problem and have written a code. Im using the wallHeatFlux BC for cooling the walls of the mould provided by you on the wiki page. When the liquid starts to solidify, i see that the temperature at the walls become lower and goes negative. could u give any suggestions about how to overcome this problem. |
All times are GMT -4. The time now is 23:19. |