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-   -   Laminar Natural Convection (http://www.cfd-online.com/Forums/openfoam/91636-laminar-natural-convection.html)

mahdiiowa August 17, 2011 15:30

Laminar Natural Convection
 
Hi Guys

I want to solve a Laminar Natural Convection problem with OPENFOAM, but as you may know the wellknown heat transfer solvers of OPENFOAM, like "buoyantBoussinesqPimpleFoam" and "buoyantBoussinesqSimpleFoam" are for turbulent flows.

So, my question is that whether I have to modify "icoFoam" to include energy equation or there are other ways of solving Laminar Natural Convection in OpenFoam.

You comments will be greatly appreciated.

Mahdi

eugene August 18, 2011 05:30

You can run laminar with the "turbulent" solvers. Just select "laminar" as the turbulence model in the RASproperties dictionary.

jignesh_thaker2007 September 27, 2011 02:58

hiiiii every one
 
hi
I m also new user of openfoam so i solved cavity tutorial also bt its for isothermal but right now i want to solve non-isothermal problem of cavity laminar flow it means natural convection flow so what r the changes require in icoFoam solver plz tel me. because in heat transfer solver there are more properties given like omega, k ,epsilon ,nutilda etc so i m so confuse to solve that so plz help me.

i m waiting for reply

Bernhard September 27, 2011 03:17

As Eugene says, you can use any solver for turbulent flow for laminar flow as well: use the laminar dummy turbulent model.

Select the solver you want to use here: http://openfoam.com/features/standard-solvers.php

omega, k, epsilon and nutilda are typical variables obtained from turbulence modelling. If you have laminar flow, you don't need those.

jignesh_thaker2007 September 27, 2011 03:33

Hello sir
 
thanks for ur kind reply

but sir in Heat transfer there r all turbulent and compressible solver so i m confusing which solver i choose?
because i solved lid-driven cavity problem with no moving velocity only temperature influence so actualy i add temp in icoFoam with the help of wikiopenfoam but i cant able to do when i give the value of velocity 0. so
plz tel me what r the modification require to solve my incompressible, laminar & nonisothermal cavity flow?

nimasam September 27, 2011 03:52

you just add temperature to icoFoam but you forget to consider the effect of buoyancy! so
if you want to consider the effect of compressibility, and its not to much, Boussinesq approximation is good! so you should use "buoyantBoussinesqPisoFoam"
and this solvers can be chosen to solve laminar case too! read above more care fully! as previously said its dummy!
for example in hot room tutorial you just need to edit RASProperties file and put instead of kEpsilon laminar!

Bernhard September 27, 2011 03:55

Did you read my post at all?
You don't need any modifications, since
1. All solver for turbulent flow can be run for laminar flow
2. From the link you can find a solver for incompressible flow and heat transfer as well

jignesh_thaker2007 September 27, 2011 04:13

ok sir i will go for buoyantBoussinesqpimpleFoam solver i only change the Ras properties as u said earlier

jignesh_thaker2007 September 28, 2011 04:18

hello every one
 
hiii
i started to solve nonisothermal cavity problem but i dont know how to give the insulated boundary condition. so plz tel me in 2D cavity left & right r my hot & cold wall but top & bottom are insulated so which condition i will put? i think its is zero gradient m i right?

nimasam September 28, 2011 04:21

you are right, zeroGradient is suitable

jignesh_thaker2007 September 28, 2011 07:12

hi
 
yes sir i solved my problem but sir i have problem to plot streamFunction i solved problem for laminar nonisothermal cavity flow with buoyantBoussinesqSimpleFoam.

when i run streamfunction then it gave me error like in the file streamFunction.c at line 456 flux field does not exist stream function not calculated so

plz tel me how can i plot streamFunction?

tel me how to plot streamFunction using buoyantBoussinesqSimpleFoam.
i found error like,

reate time

Create mesh, no clear-out for time = 0


Time: 0
--> FOAM Warning :
From function streamFunction
in file streamFunction.C at line 456
Flux field does not exist. Stream function not calculated

Time: 100

Reading field phi
Zero face: patch: 0 face: 0
#0 Foam::error:printStack(Foam::Ostream&) in "/opt/openfoam201/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#1 Foam::sigFpe::sigHandler(int) in "/opt/openfoam201/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#2 Uninterpreted:
#3
in "/opt/openfoam201/platforms/linuxGccDPOpt/bin/streamFunction"
#4 __libc_start_main in "/lib/tls/i686/cmov/libc.so.6"
#5
in "/opt/openfoam201/platforms/linuxGccDPOpt/bin/streamFunction"
Floating point exception
abcz@abcz-desktop:~/Desktop/sample$


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