Rapid increase in strength of vortices and a directional net flow due to Marangoni force in Büttiker–Landauer ratchet

Abstract

The control of the vortex flow is interesting because it may open a new way to use low-grade energy. In this study, we report a rapid increase in the strength of vortices and a directional net flow at the classical threshold Rayleigh number in the Büttiker–Landauer (BL) ratchet. In particular, by increasing the temperature difference of the BL ratchet made by connecting plural liquid chambers with flow channels that generate Marangoni force, we succeed in observing this transition. Furthermore, we show that our simple transition model that considers a critical Rayleigh number explains the experimental results qualitatively. In addition, as a result, we succeed in producing a net flow without using the additional guide-walls that prevent the isolation of the vortex flows among the plural liquid chambers.