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Re: [Question #699070]: Effect of particle size on noise in the results


Question #699070 on Yade changed:

    Status: Needs information => Open

SO TA gave more information on the question:
Hi Jan,

Sorry for my not well-defined questions! I'll response to each section
under your comments.

> I am new to DEM and I have very little experience with YADE and DEM

welcome :-)

please read [1] and provide (much) more information, ideally also a MWE
if possible.

> I am simulating ... a bucket ... a stockpile ...
please note that the simulation is not done using Yade. It is in Algoryx.  As I mentioned in my first question, my question is of more DEM nature rather than a YADE one.  I added image1 to provide you with an idea of what are bucket and stockpile.
Image 1:  https://www.dropbox.com/s/35f2vwb5vcqh9wn/Image.png?dl=0

What is "a bucket" and "a stockpile"? explained in the image (above link)
What shape do they have? explained in the image (above link)
What are they composed from (spheres, facets, ...)? the particles are spheres with uniform PSD. bucket is a rigid solid body.
What is their mutual sizes and mutual sizes of the components? the size of the bucket and stockpile is explained in the image (above link). four particle samples of 100mm, 200mm, 300mm and 400mm are simulated.
Are the components regular or not? not sure what does this mean?
... ?
... ?

> when I use large particle sizes

What is "large", large with respect to what?
300-400mm alone is useless information...
large with respect to the size and capacity of the excavator 

> the results are noisy

What is "the result"?
Positions, velocities, energies?
Numerical result or visual state?
... ?
Numerical results including cycle time (the time takes the bucket to go through the granular material) and payload (the amount of the particles in the bucket at the end of the cycle)
> slightly shifting the bucket

what is "slightly"? with respect to what?
I moved the bucket in relation to the centreline of the stockpile (Image 2) and re-run the simulations and compare the results (cycle time and payload) with those from previous simulations.  for the smaller particle sizes (100, 200, 300 mm) the difference was less than 3% while for the 400mm particles the difference between the results was more than 40%. I have been advised that using large particles in DEM results in the noise in the output and I do not quite understand why. If that is the case then how should we simulate phenomenon with large particle sizes?
> the error was huge

error of what?

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