Cyclic periodic boundary

Submitted by marcurial on Thu, 09/27/2018 - 13:52

Hello,

I'm not 100% sure about it, but i may have found a bug concerning the cyclic periodic boundary. In the appendix you can find the original periodic boundary tutorial case (I just changed the the EndTime in the controll Dict and disabled gravity). If you have a look at the drag forces in Xdirection, you can see that the sign of the drag forces is not uniform. One half of the particles has a negative one and the other half has positive one, which does not seem to be right.
I replaced the cyclic boundary condition in Xdirection with an inlet and outlet and got a uniform drag force pattern in Xdirection (as you can see in the second Case in the appendix).
I also tried different timesteps, coupling intervals, material properties,smoothing algorithms in an own case, which showed the same problem regarding the cyclic periodic boundary. It seems like the cyclic boundary condition adds a oscillation to the system.

Any ideas on this?
Already thanking you. Regards
Mark

ljmutue | Fri, 10/05/2018 - 14:01

Hello Mark,

It seems like I have the same issue as you described: when inlet BC for U is uniform (0 0 0.5), I got half particles moving upwards and half moving downwards in cross-sectional direction.
Have you got any further moves of your issue?

Cheers,
Lijing