  We present a theoretical and experimental study of boundary-driven acoustic
streaming in an inhomogeneous fluid with variations in density and
compressibility. In a homogeneous fluid this streaming results from dissipation
in the boundary layers (Rayleigh streaming). We show that in an inhomogeneous
fluid, an additional non-dissipative force density acts on the fluid to
stabilize particular inhomogeneity configurations, which markedly alters and
even suppresses the streaming flows. Our theoretical and numerical analysis of
the phenomenon is supported by ultrasound experiments performed with
inhomogeneous aqueous iodixanol solutions in a glass-silicon microchip.
