Problem with convection term

rapierrz · March 3, 2015, 11:10

Hello friends,

I have a problem with energy equation in icoFoam

fvm::ddt(T)
+fvm::div(phi,T)
-fvm::laplacian(D,T)

my boundary condition is T=353 at wall and T=293 in internalField,

but in temrature data i have T=2000-3000 and i know it's from convection

term but i don't know that's reason!!!

Cyp · March 3, 2015, 20:15

Quote:

Originally Posted by rapierrz

Hello friends,

I have a problem with energy equation in icoFoam

fvm::ddt(T)
-fvm::div(phi,T)
-fvm::laplacian(D,T)

my boundary condition is T=353 at wall and T=293 in internalField,

but in temrature data i have T=2000-3000 and i know it's from convection

term but i don't know that's reason!!!

PLUS instead of MINUS for the convection term should works

rapierrz · March 3, 2015, 23:53

Excuse me Cyprien,

my equation is :

fvm::ddt(T)

+fvm::div(phi,T)

-fvm::laplacian(D,T)

and when I remove the convection term everything is ok but when I add

this term temprature become very high!!!

Cyp · March 3, 2015, 23:57

what if you decrease your time step ?

rapierrz · March 4, 2015, 00:05

My time step is 0.000005 sec.and courant number in runtime is about 0.4

rapierrz · March 4, 2015, 02:26

Thank you very much Cyprien,

I decrease the time step to 0.0000005 and it's work!

March 3, 2015, 11:10	Problem with convection term	#1
rapierrz Senior Member Hesam Join Date: Feb 2015 Posts: 139 Rep Power: 11	Hello friends, I have a problem with energy equation in icoFoam fvm::ddt(T) +fvm::div(phi,T) -fvm::laplacian(D,T) my boundary condition is T=353 at wall and T=293 in internalField, but in temrature data i have T=2000-3000 and i know it's from convection term but i don't know that's reason!!! Last edited by rapierrz; March 3, 2015 at 23:48.

March 3, 2015, 23:57		#4
Cyp Senior Member Cyprien Join Date: Feb 2010 Location: Stanford University Posts: 299 Rep Power: 18	what if you decrease your time step ? rapierrz likes this.

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March 3, 2015, 23:53		#3
rapierrz Senior Member Hesam Join Date: Feb 2015 Posts: 139 Rep Power: 11	Excuse me Cyprien, my equation is : fvm::ddt(T) +fvm::div(phi,T) -fvm::laplacian(D,T) and when I remove the convection term everything is ok but when I add this term temprature become very high!!!

March 4, 2015, 00:05		#5
rapierrz Senior Member Hesam Join Date: Feb 2015 Posts: 139 Rep Power: 11	My time step is 0.000005 sec.and courant number in runtime is about 0.4

March 4, 2015, 02:26		#6
rapierrz Senior Member Hesam Join Date: Feb 2015 Posts: 139 Rep Power: 11	Thank you very much Cyprien, I decrease the time step to 0.0000005 and it's work!