CFD Online Logo CFD Online URL
Home > Forums > Software User Forums > OpenFOAM > OpenFOAM Programming & Development

Need Confirmation - Eulerian solver for tiny particules

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

LinkBack Thread Tools Search this Thread Display Modes
Old   August 29, 2012, 11:26
Wink Need Confirmation - Eulerian solver for tiny particules
Senior Member
Join Date: Jul 2010
Posts: 249
Rep Power: 15
fredo490 is on a distinguished road
Hi everyone, it would be nice if somebody can give me some confirmations on the general aspect of my algorithm and the "code" that follows (especially the translation of the equations). I want to setup an unsteady Eulerian solver to compute the behavior of tiny particles in a fluid (only the fluid impact the particules motion through the drag).

Nomenclature :
- \alpha volume fraction of the particles
- \vec{u} velocity of the particles
- f(Re) function of the relative Reynolds number
- \tau time respond of the particle
- \vec{V} velocity of the fluid

Continuity equation :
\frac{\partial \alpha}{\partial t} + {\nabla \alpha \vec{u}} = 0

Momentum equation
\frac{\partial \alpha \vec{u}}{\partial t} + {\nabla \alpha \vec{u} \vec{u}} = \frac{f(Re)}{\tau } \alpha (\vec{V} -\vec{u})

The algorithm I have in mind :
1) setup a "phi_alpha" flux equal to \alpha \vec{u}
2) initialize this flux in the createfield with:
"linearInterpolate(alpha)*linearInterpolate(u) & mesh.Sf()"
3) solve the continuity equation using the following code:
fvScalarMatrix cEqn
+ fvc::div(alpha_phi)
4) update the flux phi_alpha with:
alpha_phi -= cEqn.flux();
5) compute the relative Reynolds number, the function f(Re) and \tau
6) solve the momentum equation using:
fvVectorMatrix uEqn
fvm::ddt(alpha, u)
+ fvm::div(alpha_phi, u)
fRe / Tau * alpa * (V – u)
My questions are:
i) I'm not sure of the step 4... I kind of reproduce the simpleFoam code. Is there any documentation somewhere about the command ".flux" ?
ii) I'm not sure of the translation of the momentum equation step 6. Do I need to use a specific formulation for the source term ? Does the solver identify the last "u" by itself ?

Thank you in advance for reading this.

Last edited by fredo490; August 29, 2012 at 11:28. Reason: Tiny corrections
fredo490 is offline   Reply With Quote

Old   September 13, 2012, 03:24
Senior Member
Gerhard Holzinger
Join Date: Feb 2012
Location: Austria
Posts: 317
Rep Power: 26
GerhardHolzinger will become famous soon enoughGerhardHolzinger will become famous soon enough
have a look into twoPhaseEulerFoam or bubbleFoam and the thesis of H. Rusche. They all deal with a Eulerian formulation of two-phase fluid flows.

I would recommend to get into bubbleFoam or twoPhaseEulerFoam and remove everything you don't need. Particles with constant diameter and only drag as momentum exchange should not be a big problem.

Last edited by GerhardHolzinger; September 13, 2012 at 03:27. Reason: added clarifiaction
GerhardHolzinger is offline   Reply With Quote


equations, euler, particles

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
interfacing a fluid solver with abaqus Tuhin Rakshit Main CFD Forum 0 June 16, 2005 11:03
Could you comare StarCD with CFX 5?Help, please... Suteh CFX 54 November 7, 2001 21:12
CFX 5.5 Roued CFX 1 October 2, 2001 17:49
Setting a B.C using UserFortran in 4.3 tokai CFX 10 July 17, 2001 17:25
Error during Solver cfd guy CFX 4 May 8, 2001 07:04

All times are GMT -4. The time now is 23:21.