Fig. 1: Flows driven by different types of active carpets.
From: Active carpets drive non-equilibrium diffusion and enhanced molecular fluxes
Diagrams of a few examples: a Molecular motors walking along a surface, described by parallel Stokeslets. b Sessile suspension feeders that draw in feeding currents, described by perpendicular Stokeslets. c E. coli bacteria swimming along a surface, described by Stokes dipoles. d Actuators that rotate about the z-axis, such as nodal cilia, described by Stokes rotlets. e–h Flow fields generated by these different actuator types, shown in the xy plane at z0 = 2h. i–l Probability distribution functions, PDF(vz), of the total flow velocity due to Na = 105 actuators, at different heights z0. Insets show rescaled histograms that highlight skewness and kurtosis, especially for small z0 values. m–p The variance of these distributions, \(\langle {v}_{i}^{2}\rangle\), corresponding to the strength of active fluctuations in different directions i, as a function of distance z0 from the active carpet. Insets show the skewness for n and o, but this is zero for m and p. Symbols show simulation results and the lines are the theoretical predictions of Eq. (1) and Table 1.
