Sedimentation of self-propelled Janus colloids: polarization and pressure

We study experimentally-using Janus colloids-and theoretically-using Active Brownian Particles- the sedimentation of dilute active colloids. We first confirm the existence of an exponential density profile. We show experimentally the emergence of a polarized steady state outside the effective equilibrium regime, i.e. when v_s is not much smaller than the propulsion speed. The experimental distribution of polarization is very well described by the theoretical prediction with no fitting parameter. We then discuss and compare three different definitions of pressure for sedimenting particles: the weight of particles above a given height, the flux of momentum and active impulse, and the force density measured by pressure gauges

Computation of TM Scattered Fields Induced by a Truncated Semi-Elliptic Cavity in a PEC

This study investigated the scattered transverse-magnetic (TM) electromagnetic field from a truncated semi-elliptic embedded in a perfectly electric conducting plane. Boundary value analysis and the region-point-matching technique are employed to address the issues considered. The analyzed region is divided into three sub-regions, after which the tangential fields are expanded in terms of Mathieu functions into two different coordinate systems. By applying boundary conditions at two auxiliary boundaries and using the region-point-matching technique, several independent equations are constructed and subsequently simplified to generate a system of linear equations. For the validation of the obtained results, the suggested procedure is compared to the method of moment. Finally, the effects of cavity depth and incident angle on the scattering signature are inspected