Manipulating channel asymmetries to control the mobility and diffusion of anisotropic particles

Transport of noninteracting anisotropic particles is numerically investigated in a narrow two-dimensional left–right and up–down asymmetrical channel. The mobilities of passive and active particles show the same behaviors for the different left–right and up–down asymmetrical parameters of the channel, whereas their effective diffusion coefficients show very different behaviors. The effective diffusion coefficient of passive particles is far less than that of active particles and it presents a pronounced “resonance” peak. For passive particles, the mobility decreases monotonically with increasing of the particle asymmetry, and the effective diffusion coefficient is observed to be bell-shaped and there exists an optimal value of the particle asymmetry at which it takes its maximum value. For active particles, as the self-propelled velocity is increased, the mobilities of isotropic and anisotropic particles decrease and finally go to the same value. However, the gap between the effective diffusion coefficients of isotropic and anisotropic particles increases gradually with increasing of the self-propelled velocity.