Figure 2 shows the isometric and close-up views (simulation area) in our simulation of various microchannel configurations: straight, meshed and tournament configurations [9]. The geometry of microchannels is specified by the length $H$ and width $W$. The length of channel inflow is $L1$, the length of channel outflow is $L2$, and the length of the microchannel is $H-L1-L2$. Initially, the total number NPs (*N*) are distributed randomly inside a box of size $L1\xd7W$ that is located at the inlet of the microchannel. As the NPs move through the microchannel, some of the particles arrive at a box of size $L2\xd7W$ that is located at the outlet of the microchannel. Here, we set $H=180$, $L1=50$, $L2=40$, $W=220$, and $N=1100$. In order to reduce the cost of simulation, we only modeled two-dimensional sections of the microchannels, which are shown in Figs. 2(d)–2(f) (close-up view of microchannels). Our simulation boxes are $H\xd7W1$ ($180\xd720$), $H\xd7W2$ ($180\xd740$), and $H\xd7W3$ ($180\xd755$) LB units in size for straight microchannel, meshed microchannel, and tournament microchannel, respectively, which are equivalent to 1/11 of straight microchannel, 2/11 of meshed microchannel and 1/4 of tournament microchannel. The initial numbers of NPs at the upper reservoir are 100, 200, and 275 for straight microchannel, meshed microchannel, and tournament microchannel, respectively, which are equivalent to 1/11 of straight microchannel, 2/11 of meshed microchannel, and 1/4 of tournament microchannel. The LB nodes lying on the left and right boundaries satisfy periodic boundary conditions (as specified below). The dark color in the central portion represents solid barriers of microchannels, which is composed of stationary NPs. The interaction of mobile NPs and solid barrier NPs of microchannels is through excluded volume interaction. We imposed no-slip boundary condition for solid barriers of the microchannels. We also applied periodic boundary conditions in the *Y* direction.