MercuryDPM contains a unique toolbox for analysing particle data, the MercuryCG toolbox:
Three documentation pages exist for this tool:
The first page describes the mathematical formulae used to extract continuum fields from particle data. The second page tells you how to apply the analysis tool in practice, i.e. which command to use and what options to set. The third page tells you how to apply analytical output to a running MercuryDPM simulation.
Here are a few examples of the coarse-graining method applied:
The figure on the left shows a 3D particle simulation of granular flow through a thin, rectangular silo. One can observe three regions, a static zone near the side walls, a shear band, and core flow. To properly define those regions, we use coarse graining to define the velocity v(x,z), averaged over depth y and time t, then plot the normalised pure shear, shown in the right figure. One can clearly see that the pure shear is large in the shear band. By fitting the pure shear values with a Gaussian, the shear band centre and width can be clearly defined.
Coarse-graining is also applicable to molecular dynamics simulations, in this case atomistic flow through a nanochannel. Near the channel wall, we observed oscillations in the flow density, which indicates that the flow is slightly ordered. To resolve this phenomenon, a high spatial resolution is required, which can easily be obtained in coarse-graining by using a small length scale