[arb93]

Hey!

So I am new to OpenFoam and would like to be able to simulate a rotating cylinder in an otherwise stationary fluid (laminar and incompressible).

Has anyone done such studies and/or could anyone point me to existing tutorials that might help?

I really appreciate the help!

Thanks!

[kebsiali]

Hello

I've done such a task using FreeFEM++ (the cylinder rotates around its axis), I geuss you are trying to study the effect of the oscillation frequency on the resulting vortex frequency?
I think you will have to follow the same idea. everything in the solver will stay the same, you can use pimpleFoam, icoFoam, or pisoFoam.
you will have to create a new boundary condition where the velocity of each point in the cylinder surface (no slip condition) will have its value.

you will start by saying that a point at (x,y) is at x=rcos(\theta) and y=rsin(\theta)
you will define an angular velocity omega=f(time) as you like and then simple math gives velocity vector (vx,vy,vz) as a function of space and time (since every point will have its velocity components)

your task will be to create a new boundary condition type in openfoam

search for that. there are many tutorials.

[arb93]

Thanks, but I am actually not trying to simulate an oscillating cylinder.

Just a cylinder rotating at a constant speed in a fluid.

[alexeym]

Hi,

Is it similar to tutorials/incompressible/SRFPimpleFoam/rotor2D? (though it is fluid rotating around static rotor).

Is it transient case? Do you need to track free surface of the fluid?

[arb93]

I don't need to track the free surface of the liquid and it is steady state for now.

Thanks in advance!

[alexeym]

Start with tutorials/incompressible/SRFSimpleFoam/mixer. It is again fluid rotating around static mixer boundary. You need to make mesh more simple (in you case inner wall is just a cylinder), change RASModel to laminar, and case become the one you have described in your post.

[arb93]

Thank you!

[kkpal]

How about try setting the boundary velocity of the cylinder to

rotatingWallVelocity

?

[ShanuNith]

hey,
I have a doubt in my mind, how do i know the axis direction of my rotating cylinder.

/*--------------------------------*- C++ -*----------------------------------*\
========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration | Website: https://openfoam.org
\\ / A nd | Version: 7
\\/ M anipulation |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class volVectorField;
location "0";
object U;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions [0 1 -1 0 0 0 0];

internalField uniform (0 0 0);

boundaryField
{
leftWall
{
type noSlip;
}
rightWall
{
type noSlip;
}
lowerWall
{
type noSlip;
}
atmosphere
{
type pressureInletOutletVelocity;
value uniform (0 0 0);
}
cylinder1Wall
{
type rotatingWallVelocity;
origin (-0.035 0 -1);
axis (0 0 1);
omega constant -2; //rad per sec
}
cylinder2Wall
{
type rotatingWallVelocity;
origin (0.035 0 1);
axis (0 0 1);
omega constant 2; //rad per sec
}
defaultFaces
{
type empty;
}
}


// ************************************************** *********************** //

i have two cylinders of which the first cylinder is at left and second is at right. Left one is to be rotated in clockwise directiln while the right on is to be roated in counter-clockwise direction such that a converging velocity field is made in between the cylinders. but i am not sure how to define the direction because i exactly dont know what (0 0 1) represtns in front of axis. and what if its is (0 0 -1)

I am really confused.

[Nasos_bal]

Originally Posted by arb93

Hey!

So I am new to OpenFoam and would like to be able to simulate a rotating cylinder in an otherwise stationary fluid (laminar and incompressible).

Has anyone done such studies and/or could anyone point me to existing tutorials that might help?

I really appreciate the help!

Thanks!

Hello! I am trying to simulate a fluid inside a cylinder which is 5 degrees inclined. Could you help me?