2020-6-4 Meeting notes Dariel

SuperQuadrics: BoundingSphereRadius

Prolate ellipsoids don't work; Mercury does not detect overlaps;

this is because teh BoundingSphereRadius is miscomputed;

Dariel is looking at correcting that function, using the Alexander Podzhuk paper.

He needs to add special cases in if-statements.

Problems

• outputting axis in setBoundingRadius results in wrong values

SuperQuadrics: Contact detection

• Blockiness of 0.1 causes contact point detection to fail

• The paper by Alexander P. on which the Mercury algorithm is based says convergence is guaranteed for blockiness >0.25

• Dariel will take a look whether this can be fixed; but not priority

MercuryCG

Dariel reported a problem running MercuryCG on SuperQuadric particles (loadRestart does nto seem to work)

Thomas will take a look once he has Dariels restart files

Angle distribution

Dariel corrected the distribution of angles (relative to the velocity vector) by sin(theta)/2, but the data for spheres (AR=1) is not perfectly uniform (it should be); also, the data has a large standard deviation

• I told him to use the data files instead of the restart files because they contain more timesteps; and look for errors

Surface velocity profiles

Dariel sees a  difference with aspect ratio in surface velocity profiles of mixed flows: The peak velocity is reached earlier for high aspect ratios. Unknown origin

Working Document

To write a paper, we need to understand what are teh two segregation drivers that cause  a flip in segregation direction at AR~3

Dariel should start a working document, where we keep results as they come in

kinetic stress

The kinetic stress trace is higher at the flowing layer in each aspect ratio, The kinetic pressure is lower in the range of aspect ratios which are close to AR = 1.

fstat files for nonspherical particles

There are NaN numbers. It is important to know how they come.

coarse graining (fstatics and MercuryCG)

Dariel obtained the error: This function should not be used