CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > OpenFOAM > OpenFOAM Pre-Processing

Dimensions in ScalarTransportFoam

Register Blogs Members List Search Today's Posts Mark Forums Read

Like Tree1Likes
  • 1 Post By Traction

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   November 26, 2017, 10:15
Default Dimensions in ScalarTransportFoam
  #1
New Member
 
Dan
Join Date: Sep 2016
Posts: 20
Rep Power: 9
Gesetzt is on a distinguished road
Hi,

I have an simple question. I'm referring to OF 4.1.

There is the definition of the equation:
fvScalarMatrix TEqn
(
fvm::ddt(T)
+ fvm::div(phi, T)
- fvm::laplacian(DT, T)
==
fvOptions(T)
);

So, this means: \frac{\partial T}{\partial t} +\nabla\cdot{(\phi T)}-\nabla(\Gamma \nabla T)=0.

For incompressible fluids phi means: U \cdot A. I don't get the dimensions right here. For the first term it's obviously \frac{K}{s}. But for the second term phi has to be U, to get the right dimension.

I looked up phi and it says: surfaceScalarField phi

(
IOobject
(
"phi",
runTime.timeName(),
mesh,
IOobject::READ_IF_PRESENT,
IOobject::AUTO_WRITE
),
fvc::flux(U)
);

So what exactly is meant with flux(U), is this without the area? I couldn't find the code definition of flux(U).

I hope someone can help me to clarify this topic.

Best regards

Gesetzt
Gesetzt is offline   Reply With Quote

Old   November 27, 2017, 04:55
Default
  #2
Member
 
Join Date: Mar 2014
Posts: 39
Rep Power: 12
Traction is on a distinguished road
Quote:
Originally Posted by Gesetzt View Post
So what exactly is meant with flux(U), is this without the area? I couldn't find the code definition of flux(U).
Hi,
please have a look at src/finiteVolume/finiteVolume/fvc/fvcFlux.C where the volVectorField is U in your case! Makes things clearer ?
Gesetzt likes this.
Traction is offline   Reply With Quote

Old   December 3, 2017, 06:48
Default
  #3
New Member
 
Dan
Join Date: Sep 2016
Posts: 20
Rep Power: 9
Gesetzt is on a distinguished road
Hey,

Thanks. I think it's clear now. Part of the problem was, that I didn't thought about the fact we are using FVM, so for the discretisation over all faces we need the area.

Best Regards,

Gesetzt
Gesetzt is offline   Reply With Quote

Old   February 16, 2018, 03:27
Default
  #4
Member
 
Ramana
Join Date: Jul 2017
Location: India
Posts: 58
Rep Power: 8
svramana is on a distinguished road
Quote:
Originally Posted by Gesetzt View Post
Hi,

I have an simple question. I'm referring to OF 4.1.

There is the definition of the equation:
fvScalarMatrix TEqn
(
fvm::ddt(T)
+ fvm::div(phi, T)
- fvm::laplacian(DT, T)
==
fvOptions(T)
);

So, this means: \frac{\partial T}{\partial t} +\nabla\cdot{(\phi T)}-\nabla(\Gamma \nabla T)=0.

For incompressible fluids phi means: U \cdot A. I don't get the dimensions right here. For the first term it's obviously \frac{K}{s}. But for the second term phi has to be U, to get the right dimension.

I looked up phi and it says: surfaceScalarField phi

(
IOobject
(
"phi",
runTime.timeName(),
mesh,
IOobject::READ_IF_PRESENT,
IOobject::AUTO_WRITE
),
fvc::flux(U)
);

So what exactly is meant with flux(U), is this without the area? I couldn't find the code definition of flux(U).

I hope someone can help me to clarify this topic.

Best regards

Gesetzt
HI,
i have question about TEqn. can this be valid for porous simple foam also.
svramana is offline   Reply With Quote

Reply

Tags
scalartransportfoam

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Different dimensions for = dimensions : [0 2 -1 0 0 0 0] = [0 4 -3 0 0 0 0] mohakbl111 OpenFOAM Running, Solving & CFD 5 February 6, 2019 06:37
FOAM FATAL ERROR for Different dimensions rupesh_w OpenFOAM Running, Solving & CFD 2 April 27, 2016 05:14
Incompatible dimensions for operation ruben23 OpenFOAM Running, Solving & CFD 2 June 12, 2015 05:14
Software that can stretch the overall dimensions of a mesh. Robert_B Main CFD Forum 2 January 27, 2012 08:39
Units in scalartransportfoam Frithjof OpenFOAM 1 January 5, 2011 11:41


All times are GMT -4. The time now is 13:25.