Finite volume calculus

Sujatha · October 15, 2013, 16:06

Hi all...
I am a newbie to openfoam and cfd.
I cant understand the finite volume calculus described in openfoam as a discretization method. I can't understand what exactly is that. I couldn't find any such method in text books etc.
I will be grateful to get some hint regarding the topic.

Thanks in advance.

Regards
Sujatha

ARTem · October 16, 2013, 05:17

Hello, Sujatha.

OpenFOAM uses finite volume method (FVM) to discretize differential equations. FVM can easily be found in most of CFD books.

sam.ho · October 16, 2013, 07:51

Hi Sujatha,

Even i am a new member

Kindly Go through "Jasak, H.: Error analysis and estimation for the Finite Volume method with applications to fluid flows, PhD. Thesis, Imperial College, University of London, 1996" this thesis.

this will give you more insight

Cheers
Sam.Ho

Sujatha · October 16, 2013, 09:18

Thank you Artem and Sam ho for your quick response.
But I was asking about FINITE VOLUME CALCULUS mentioned in page 29 of programmers guide of OpenFOAM 2.2.1 and not finite volume method or are both the same thing said in different names, if so please explain the significance of such a differentiation.
I guess this time I have made my doubt specific.

"Each term in a PDE is represented individually in OpenFOAM code using the classes
of static functions finiteVolumeMethod and finiteVolumeCalculus, ".......page 29 of programmers guide

I will be grateful to get any response.
Regards,
Sujatha

ARTem · October 16, 2013, 10:46

Hello, Sujatha.
Functions located under namespace fvm (FiniteVolumeMethod) return you coefficients for matrix equation (central a_p and neighbours a_nb). At the other hand, functions located under namespace fvc (FiniteVolumeCalculus) return you fields.
E.g. fvm::div(phi, A), with phi being convective flux and A being scalar parameter, gives you matrix with coefficients, which you can solve with respect to A. fvc::div(phi*A) gives you just sink or source values of parameter A from convection of A through faces.
Basically, it's implicit (fvm) and explicit (fvc) discretisations.

Sujatha · October 16, 2013, 11:40

Thank you Artem. This explanations now helps me. I really wanted to confirm that both the names implies the same method of discretization.
Thanks a million.
Regards
sujatha

October 15, 2013, 16:06	Finite volume calculus	#1
Sujatha New Member Join Date: Jul 2013 Posts: 27 Rep Power: 12	Hi all... I am a newbie to openfoam and cfd. I cant understand the finite volume calculus described in openfoam as a discretization method. I can't understand what exactly is that. I couldn't find any such method in text books etc. I will be grateful to get some hint regarding the topic. Thanks in advance. Regards Sujatha

October 16, 2013, 10:46		#5
ARTem Member Artem Shaklein Join Date: Feb 2010 Location: Russia, Izhevsk Posts: 43 Rep Power: 16	Hello, Sujatha. Functions located under namespace fvm (FiniteVolumeMethod) return you coefficients for matrix equation (central a_p and neighbours a_nb). At the other hand, functions located under namespace fvc (FiniteVolumeCalculus) return you fields. E.g. fvm::div(phi, A), with phi being convective flux and A being scalar parameter, gives you matrix with coefficients, which you can solve with respect to A. fvc::div(phi*A) gives you just sink or source values of parameter A from convection of A through faces. Basically, it's implicit (fvm) and explicit (fvc) discretisations. granzer likes this.

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October 16, 2013, 05:17		#2
ARTem Member Artem Shaklein Join Date: Feb 2010 Location: Russia, Izhevsk Posts: 43 Rep Power: 16	Hello, Sujatha. OpenFOAM uses finite volume method (FVM) to discretize differential equations. FVM can easily be found in most of CFD books.

October 16, 2013, 07:51	Hi	#3
sam.ho Senior Member Join Date: Sep 2013 Location: Bangalore India Posts: 134 Rep Power: 12	Hi Sujatha, Even i am a new member Kindly Go through "Jasak, H.: Error analysis and estimation for the Finite Volume method with applications to fluid flows, PhD. Thesis, Imperial College, University of London, 1996" this thesis. this will give you more insight Cheers Sam.Ho

October 16, 2013, 09:18		#4
Sujatha New Member Join Date: Jul 2013 Posts: 27 Rep Power: 12	Thank you Artem and Sam ho for your quick response. But I was asking about FINITE VOLUME CALCULUS mentioned in page 29 of programmers guide of OpenFOAM 2.2.1 and not finite volume method or are both the same thing said in different names, if so please explain the significance of such a differentiation. I guess this time I have made my doubt specific. "Each term in a PDE is represented individually in OpenFOAM code using the classes of static functions finiteVolumeMethod and finiteVolumeCalculus, ".......page 29 of programmers guide I will be grateful to get any response. Regards, Sujatha

October 16, 2013, 11:40		#6
Sujatha New Member Join Date: Jul 2013 Posts: 27 Rep Power: 12	Thank you Artem. This explanations now helps me. I really wanted to confirm that both the names implies the same method of discretization. Thanks a million. Regards sujatha