Originally Posted by gpextra (Post 315458)

Dear colleagues,

I am making use of this post to show you a similar problem I have had using rotating walls with OpenFoam. I am a beginner (in OpenFoam) and this is the case:

It is a lid-driven cavity problem where the lid is not flat, but a rotating cylinder. The solver was icoFoam from OpenFoam 2.0.0. Conceptually this is exactly the same old 2D lid-driven cavity, but with this slightly different geometry. The internal flow details are unimportant and I will focus only on the wall velocity. This is part of the mesh dictionary to illustrate the very simple geometry:

convertToMeters 0.001;
vertices
(
(0 0 0) // 0
(1 0 0) // 1
(1 1 0) // 2
(0 1 0) // 3
(0 0 1) // 4
(1 0 1) // 5
(1 1 1) // 6
(0 1 1) // 7
);
blocks
(
hex (0 1 2 3 4 5 6 7) (20 20 1) simpleGrading (1 1 1)
);
edges
(
arc 3 2 (0.5 1.5 0)
arc 6 7 (0.5 1.5 1)
);

The velocity boundary condition for the (rotating) lid is is specified as

bump
{
type rotatingWallVelocity;
origin (0.5 1 0);
axis (0 0 1);
omega 0.001; // a rather small value!
}

Well, I would expect that the wall absolute velocity was constant, and the x and y-velocities were of sin or cos shaped. But no! The wall velocity profile, shown in the attached figure, has a misbehaving y-velocity component with one full period of a sine (the x-velocity component is not that bad).

In fact this is a simplified version of my real problem, where I identified this weird behavior, just to illustrate the essence of the problem with rotating walls. I have also attached a zipped file with all the other relevant files, in case someone wants to run the case.

I hope someone can help me with this weirs wall velocity profile.

Regrads,
G.Paulo.

Originally Posted by tfuwa (Post 416367)

Hi Foamers,

Hope this thread is still active. I would like to set a time-dependent rotating speed, for instance,

t<10, omega=5;
t>10, omega=0;

Is it possible to do this with rotatingWallVelocity? Many thanks.

Regards,
Albert