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-   -   SimpleFoam with body force gravity (https://www.cfd-online.com/Forums/openfoam-solving/60166-simplefoam-body-force-gravity.html)

alexice June 16, 2006 07:02

Hello everybody, Did anybod
 
Hello everybody,

Did anybody already modify the simpleFoam solver to include a body force term, i.e. gravity. I would like to add that and look for some hints.

Thanks for all advice

hartinger June 16, 2006 08:27

look at buoyantFoam, it is in
 
look at buoyantFoam, it is in there

markus

alexice June 16, 2006 09:02

thanks, right I just look at t
 
thanks, right I just look at that. I'm new to OpenFoam so it might take me a while to get into the code. buoyantFoam uses a variable density as I understand it, whereas I treat a constant density case.

I want to let the fluid move driven by gravity. Is it maybe simpler to just define the pressure gradient instead of including it in the solver? I guess this is possible in OpenFoam ;-)

hartinger June 16, 2006 09:58

twoLiquidMixingFoam is incompr
 
twoLiquidMixingFoam is incompressible, try that

Ladnam January 3, 2012 10:11

Is this the last word in this case?

Is it not possible to model steady-state, single phase, incompressible, laminar flow with gravity in OpenFoam? :(

sharonyue May 10, 2013 03:27

Quote:

Originally Posted by Ladnam (Post 337669)
Is this the last word in this case?

Is it not possible to model steady-state, single phase, incompressible, laminar flow with gravity in OpenFoam? :(

I also want to try this. Did you find the solution?

Thanks

Tushar@cfd May 14, 2013 01:03

Quote:

Originally Posted by sharonyue (Post 426473)
I also want to try this. Did you find the solution?

Thanks

Quote:

Originally Posted by Ladnam (Post 337669)
Is this the last word in this case?

Is it not possible to model steady-state, single phase, incompressible, laminar flow with gravity in OpenFoam? :(

Did you get the solution?
Instead of variable density suppose I want constant density.
Do you think the answers in both cases will differ?
I too want to know the answer..

sachin May 14, 2013 11:44

Quote:

Originally Posted by Tushar@cfd (Post 427310)
Did you get the solution?
Instead of variable density suppose I want constant density.
Do you think the answers in both cases will differ?
I too want to know the answer..

Hi Tushar,
I guess you might have already traced out solution....
Anyways if your rho is fixed you just have to add it as source term in UEqn.h() with g as vector.
u may define them in create Fields.h. So the efftect will be seen as source term in weight of fluid in only 1 momentum eq but rest would remaiin the same as before...
Correct me if i am wrong ...

Sachin

Tushar@cfd May 15, 2013 00:32

Quote:

Originally Posted by sachin (Post 427496)
Hi Tushar,
I guess you might have already traced out solution....
Anyways if your rho is fixed you just have to add it as source term in UEqn.h() with g as vector.
u may define them in create Fields.h. So the efftect will be seen as source term in weight of fluid in only 1 momentum eq but rest would remaiin the same as before...
Correct me if i am wrong ...

Sachin

Thanks for replying..

I have already done that thing with buoyantSimpleFoam... But later dropped the idea as it didn't suit my requirements and worked with Boussinesq approximation. If you see the code here variable density is needed for buoyancy..

I think I should say in detail, since I am working with buoyantBoussinesqSimpleFoam...

I have solution but these differs from the numerical approach of the papers. For a very simple case the results matches exactly with the journal papers. But for the case of complex geometry results are showing deviations from paper. Which I don't think is permissible, with the use of higher order schemes and since the results are reaching convergence(I have set below 1e-05 for all variable is my convergence criteria). When I happen to see the Isotherms and streamlines the dissipations seems to match with the paper but the gradT value is differs. It seems convective dissipation of heat in OF is more.

Anyways, I am trying to figure it out.

Is there anyone who has solved a complex case of natural convection (especially with buoyantBoussinesqSimpleFoam)?

Tushar@cfd May 15, 2013 00:56

Well,

Anyone successful in solving natural convection of complex geometry (like heat transfer inside a room with a source object).

If yes please, try to share your views.. Are you getting the exact results (as compared with numerical results of papers)?

Thanks in Advance..

:)

sachin May 15, 2013 09:13

Sounds interesting ... Can you share the data ... what is the complexity...
CAn you share the difference ...

Points you can check -
1. What is effect of variation in Tref in boussinesq approximation
2. What is your Rayliegh number ... is it very high .. in which case it would turbulent flow
3. Changes in mesh

Best Luck
Sachin

Tushar@cfd May 15, 2013 23:32

Quote:

Originally Posted by sachin (Post 427733)
Sounds interesting ... Can you share the data ... what is the complexity...
CAn you share the difference ...

Points you can check -
1. What is effect of variation in Tref in boussinesq approximation
2. What is your Rayliegh number ... is it very high .. in which case it would turbulent flow
3. Changes in mesh

Best Luck
Sachin

Condition1:
I didn't understand this. What do you mean by variation in Tref in boussinesq approximation? Can you please explain, what kind of variation you are talking about?
:rolleyes:

Condition 2:
I already shared the data check my post...
http://www.cfd-online.com/Forums/ope...implefoam.html

Condition 3:
Well, if I am right then mesh size won't have much impact on results in case of SIMPLE algorithm.
;)

sachin May 16, 2013 07:47

I was refering to your ref temperature/ambient temperature...
I understand that these solvers might have some problems with complex geometries but the case described doesnt really seems to be a complex geometry ...
For mesh, I dont know why it is not important. your concern from what understand is not something about no convergence but about dissipation of heat. So, if the mesh does capture the heated boundary condition, the results might improve.

To check if the OF is giving some problem, you can compare it with some other s/w.
With no real case results, we can keep guessing what you can try...

If I could still thing of any more ideas, I would keep you posted.
If you do solve your problem, let me know.

Best Luck,
Sachin

Tushar@cfd May 16, 2013 08:07

I am very confident about my results.

Anyways, I am trying to figure out the same with other options.


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