about Rayleigh numbe
 

hi all

how can i get or calculate Rayleigh number.

related docs: http://en.wikipedia.org/wiki/Rayleigh_number

best regards

User your calculator.
Or try to give us some more details.

about Rayleigh number
 

hi sega

i want an utility tool, or some help to develop once to calculate Rayleigh number as field.

to do this i need
- rho field
- T field
- nu and alpha

Do you have any knowledge about OpenFOAM programming so far, or are you a beginner?

i am new in openfoam programming, do you think that openfoam programming guide is enough to write a small utility.

No, I don't think so.
I suggest you take a look at the slides from the 4th OpenFOAM Workshop.
Especially the Basic Training slides should be of interest to you.
In particular these:

• OpenFOAM programming tutorial
• Basics of C++ and OpenFOAM
• Introduction to C++ for CFD modeling

Have fun!

thank you sega for your help and time

after reading this material i know how

-compile an solver
-add a new scalartransportproprieties like nu
-declaration of fields in creatfields.H

i hope to implement my own solver
but there is some thing i dont understand when

i tray to compile this equation inspired from programming tutorial

d(T)/dt + U*grad(T) = nu*laplacian(T)

i get some thing like this

[caelinux@localhost icoFoam]$ wmake
Making dependency list for source file icoFoam.C
SOURCE=icoFoam.C ; g++ -m32 -Dlinux -DDP -Wall -Wno-strict-aliasing -Wextra -Wno-unused-parameter -Wold-style-cast -O3 -DNoRepository -ftemplate-depth-40 -I/home/caelinux/OpenFOAM/OpenFOAM-1.4.1/src/finiteVolume/lnInclude -IlnInclude -I. -I/home/caelinux/OpenFOAM/OpenFOAM-1.4.1/src/OpenFOAM/lnInclude -fPIC -pthread -c $SOURCE -o Make/linuxGccDPOpt/icoFoam.o
icoFoam.C: In function ‘int main(int, char**)’:
icoFoam.C:83: error: no match for ‘operator==’ in ‘Foam::fvm::laplacian(const Foam::volScalarField&, Foam::GeometricField<Type, Foam::fvPatchField, Foam::volMesh>&) [with Type = double](((Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>&)(& p))) == Foam::operator-(const Foam::tmp<Foam::GeometricField<Type, PatchField, GeoMesh> >&) [with Type = Foam::Vector<double>, PatchField = Foam::fvPatchField, GeoMesh = Foam::volMesh]()’
/home/caelinux/OpenFOAM/OpenFOAM-1.4.1/src/OpenFOAM/lnInclude/cellModelI.H:124: note: candidates are: bool Foam::operator==(const Foam::cellModel&, const Foam::cellModel&)
/home/caelinux/OpenFOAM/OpenFOAM-1.4.1/src/OpenFOAM/lnInclude/edgeI.H:147: note: bool Foam::operator==(const Foam::edge&, const Foam::edge&)
make: *** [Make/linuxGccDPOpt/icoFoam.o] Error 1



what that mean, if you know,

errors related to
operator==
operator+

Well how did you actually implement the equation?
Can you show us some code?
How is this related to the Rayleigh number?

the goal is to do some simulation for a specified Ra number 10E4 .. 10E7

Ra number is used in dimensionless "no dimonsioned" equations like here

http://www-cast3m.cea.fr/cast3m/html...35/node50.html

Ra=Gr.Pr


but open foam use a dimensioned equations

so i have two choice

use openfoam dimensioned equations and calculate Ra number after

or write a new solver " equation with no dimension by changing dimension parameters in SetDimension.H", i prefer this second coice because i can control Ra numbre and i dont have to calculate it

i guess

what do you think

ragards