Hi, everyone here.
I have a quite simple and 'stupid' question : )
In my cases, i'm using 'cetre voidfractionModel' and 'dense averagingModel' for that my particle radius is quite smaller than CFD cell and that particles are dense. Please correct me if i'm wrong.
It seems that too small ratio would cause a problem for dense packings. So can anyone tell me, how i set proper RATIO of DEM particle diameter(radius) with CFD cells ?
Regards,
Mq
Jing Lu | Fri, 06/13/2014 - 05:52
Hi, in my case the ratio of
Hi, in my case the ratio of particle diameter to fluid cell should be smaller than 1:4.
But I haven't dug into the lower limit you are asking. Would you please share details of your problem with too small ratio?
Jing
tju_coastlab_mq | Fri, 06/13/2014 - 18:21
Hi, Jing
In this Forum, Chris once said that 'generally spoken, the particles should be smaller than the cells (cell/particle diameter= ~3). Everything else will lead to errors especially for dense packings'. Sorry about that I may miss the point about his opinion.
I am building the case, before which i try to understand as much as possible about these parameters. I may use about 0.1mm as particle diameter but larger than 10mm as CFD cell size. You can see, it's quite a tiny ratio : /
So I am wondering what is the lower limit of the ratio.
cgoniva | Thu, 06/26/2014 - 11:56
Hi,
Hi,
3-4 particles per cell is a reasonable range, if particles are much smaller than the cells it should still work, but depending on interpolation all particles in the cell will see the same flow velocity.
You are basically "giving away" possible resolution.
Small side note: the interpolation can cause numerical instabilities.
Kind regards,
Chris