Capillary as a liquid diode
Manjinder Singh, Avinash Kumar, Abdul Rahman Khan
Abstract
We present a theoretical investigation of liquid imbibition into capillaries with axially varying geometry. We show that using appropriate geometry and wettability, converging capillaries, in principle, can act as a liquid diode. We explain the underlying mechanics and conditions that make a converging capillary a liquid diode. Further, we describe a methodology to enhance the rate of liquid imbibition into the proposed diode. We mathematically show that creating a wettability gradient along the axial length of the capillary diode enhances the rate of liquid imbibition compared to a capillary diode with uniform wettability. Our mathematical model predicts that using a wettability gradient along the axial length of the capillary diode decreases the imbibition time by more than 30% compared to a capillary diode with uniform wettability.Received 7 April 2020Accepted 10 September 2020DOI:https://doi.org/10.1103/PhysRevFluids.5.102101©2020 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasImbibition & injectionSurface tension effectsWettingFluid Dynamics