Originally Posted by Aelsawis (Post 250415)

I' am trying to model the behavior of a non newtonian fluid inside an eccentric annulus. I need to get a profile of the annular velocity of the fluid for the whole cross section. I just discovered the OpenFoam and i was wondering if the "nonNewtonianIcoFoam" solver would manage a problem like this? Since i am new in this area any further help or suggestions is appreciated. What should i read to get started? Is there another solver that is more specialized in Annular flow? Will i need a mesh generation program(Boundary conforming grid generator) or Will the Openfoam handle the whole problem?

Really appreciate any help :)

Originally Posted by kev4573 (Post 249385)

Did this issue ever get resolved? Both tutorials for potentialFoam seem to give incorrect pressure distributions if you run the simulation with the '-writep' argument. It does seem the pressure field resembles phi more than anything.

Originally Posted by ngj (Post 183046)

Hi Roberto

You need to program a new boundary condition (at least that is what I think). The programming is rather simple, and I have something at another computer, which might help you. The short story is, that you know the point on the surface, x_S, and the center of the cylinder, x_0. Then specify

v = x_S - x_0.

Say that the angular frequency is omega, then the boundary condition for the velocity for the cylinder surface in any given point is given as (assume 2D)

U = - omega * vector(-v_2,v_1,0)

where v_1 and v_2 are the first and second component of v. Assumed that the cylinder rotates clockwise, if anti-clockwise just remove the minus in front.

Have fun, and if you need my source, just send me an email.

- Niels

Originally Posted by ngj (Post 183049)

Hi Roberto

As you said in the email, you are not completely sure how to compile, so I will make a small walk-through:

First here is the boundary condition.

http://www.cfd-online.com/OpenFOAM_D...hment_icon.gif rotatingCylinder.tar.gz

Unpack the archive and from the command-line you go into the directory and type:


This creates a dynamic library which is placed in the folder $FOAM_LIBBIN. The library is called librotatingCylinderFvPatchVectorField.so.

Then unpack the following

http://www.cfd-online.com/OpenFOAM_D...hment_icon.gif viscosityTest.tar.gz

which is a small test case with to concentric circles, where the large one rotates with a given cyclic frequency. The frequency and the center of the rotating cylinder is given in case/0/U. The library is only for 2D-case in the xy-plane, as I have not extended the code. Notice that the linking of the new boundary condition to icoFoam happens through /case/system/controlDict, where the library is added at the bottom.

Hope it works, otherwise to not hesitate to ask.

/ Niels

BTW: The setup is actually how viscosity was measured, because the flow is a couette-type of flow for large radii and small gaps. Thus the velocity profile is known, and therefore by measuring the force acting on the still cylinder, the viscosity can be determined as the velocity of the 'lid' is known.

Originally Posted by ngj (Post 183046)

Hi Roberto

You need to program a new boundary condition (at least that is what I think). The programming is rather simple, and I have something at another computer, which might help you. The short story is, that you know the point on the surface, x_S, and the center of the cylinder, x_0. Then specify

v = x_S - x_0.

Say that the angular frequency is omega, then the boundary condition for the velocity for the cylinder surface in any given point is given as (assume 2D)

U = - omega * vector(-v_2,v_1,0)

where v_1 and v_2 are the first and second component of v. Assumed that the cylinder rotates clockwise, if anti-clockwise just remove the minus in front.

Have fun, and if you need my source, just send me an email.

- Niels

Originally Posted by Ben UWIHANGANYE (Post 694301)

wmake libso



Dear Niels,


I have tried to go through this exercises and when i run icoFoam got the following fatal error:


--> FOAM FATAL IO ERROR:
keyword pFinal is undefined in dictionary "/home/ben/OpenFOAM/ben-4.1/run/visicosity/system/fvSolution.solvers"

file: /home/ben/OpenFOAM/ben-4.1/run/visicosity/system/fvSolution.solvers from line 0 to line 38.

From function const Foam::dictionary& Foam::dictionary::subDict(const Foam::word&) const
in file db/dictionary/dictionary.C at line 642.

FOAM exiting


Can you help to correct that error?


I would appreciate your help



I would appreciate you support.!