Figure 1.

(a) Simulated particles: hard disks with diameter $\sigma$ and hard needles with characteristic length $l_0$. (b) Simulation snapshot of disks ($\sigma /l_0=3$) forming chains along the director $\overrightarrow{n}$ (approximately in horizontal direction). On the outer disks and between disks surface depletion zones with low needle density form. (c) Disk distance r and disks angle $\vartheta$ towards the director $\vartheta$ are used to describe the potential of mean force as well as other interactions. (d) Needle center of mass density distribution ${\rho }^{\prime }(\overrightarrow{r})$ around a disk, relative to the director for different relative disk sizes ${\sigma }^{\prime }=\sigma /l_0$ (scale bars are one needle length $l_0$). For small disks, there are distinct depletion zones in front of and behind a disk. Depletion zone extensions are $O(l_0)$. Overlap of these depletion zones gives rise to the density-dependent depletion interaction. (Figure created using gnuplot 5.2 (http://www.gnuplot.info/), matplotlib 3.2.1 (https://matplotlib.org/), python 3.8.2 (https://www.python.org/), inkscape 0.92.5 (https://inkscape.org/)).