  We investigate the swim pressure exerted by non-chiral and chiral active
particles on convex or concave circular boundaries. Active particles are
modeled as non-interacting and non-aligning self-propelled Brownian particles.
The convex and concave circular boundaries are used as models representing a
fixed inclusion immersed in an active bath and a cavity (or container)
enclosing the active particles, respectively. We first present a detailed
analysis of the role of convex versus concave boundary curvature and of the
chirality of active particles on their spatial distribution, chirality-induced
currents, and the swim pressure they exert on the bounding surfaces. The
results will then be used to predict the mechanical equilibria of suspended
fluid enclosures (generically referred to as 'droplets') in a bulk with active
particles being present either inside the bulk fluid or within the suspended
droplets. We show that, while droplets containing active particles and
suspended in a normal bulk behave in accordance with standard capillary
paradigms, those containing a normal fluid exhibit anomalous behaviors when
suspended in an active bulk. In the latter case, the excess swim pressure
results in non-monotonic dependence of the inside droplet pressure on the
droplet radius. As a result, we find a regime of anomalous capillarity for a
single droplet, where the inside droplet pressure increases upon increasing the
droplet size. In the case of two interconnected droplets, we show that
mechanical equilibrium can occur also when they have different sizes. We
further identify a regime of anomalous ripening, where two unequal-sized
droplets can reach a final state of equal sizes upon interconnection, in stark
contrast with the standard Ostwald ripening phenomenon, implying shrinkage of
the smaller droplet in favor of the larger one.
