Universal oscillatory dynamics in capillary filling

Abstract

Capillary filling dynamics is ubiquitous in biological and natural processes. While capillary imbibition in narrow conduits has been extensively studied in the literature, any generalization in the oscillatory characteristics of the capillary front, typically observed towards the end of capillary filling processes, remains elusive. Considering Newtonian fluids, here, we demonstrate the realization of a unique universal signature of the oscillatory dynamics of the capillary front, by collapsing all relevant data in terms of the pertinent dimensionless parameters, leading to a single master curve. We further delineate the validity of our claim through extensive experiments, using four different fluids, and phase-field numerical simulations. These results may bear far reaching consequences towards explaining the capillary filling processes in a wide variety of applications ranging from nature to energy.

Electric-field-mediated morpho-dynamic evolution in drop–drop coalescence phenomena in the inertio-capillary regime

“… The alteration in drop apex owing to viscous effects can be better realized by imposing force balance on the protrusion, analogous to the formulation of capillary filling problem (Dhar et al. 2019), where the capillary stress drives the upward motion and the viscous stress resists it, as shown schematically in figure 4( c ). Assuming that the protrusion is cylindrical throughout the upward stretching, the dimensional force balance condition can be written as where is the infinitesimal surface area.…”

Microfluidics on Porous Substrates Mediated by Capillarity-Driven Transport

“…Here, the oscillations of the liquid column at the Jurin height (i.e., the equilibrium height of liquid in a vertical capillary when the weight of liquid column is balanced by the surface tension force) have been modeled by the unique interplay between inertial and gravitational forces, in addition to the viscous and surface tension forces. The oscillations persist until the effect of inertial energy near the equilibrium height has been completely suppressed by viscous damping …”

“…The oscillations persist until the effect of inertial energy near the equilibrium height has been completely suppressed by viscous damping. 18 In diagnostic applications of microfluidic analytical devices, handling of certain physiological fluids (e.g., blood) are involved, which generally deviate from Newtonian constitutive behavior. The transport of blood through microchannels has been studied by Chakraborty et al, using analytical and numerical methods, where blood has been modeled as a non-Newtonian power law fluid.…”

Quantifying Moisture Penetration in Encapsulated Devices by Heavy Water Mass Spectrometry: A Standard Moisture Leak Using Poly(ether-ether-ketone)

“…Unfortunately, the direct use of mass spectrometry for detecting leaks transporting H 2 O molecules is challenged by the high and variable background signals of the water vapor universally present in vacuum systems. This variability, together with the nonrepeatable and fluctuating behavior of water leak rates in channels, − means that there are currently no commercially available calibrated moisture leaks. As a practical measure, helium leak testing has been adopted as a de facto measurement to assess water leaks based on the implicit assumption that the rate of helium permeation correlates well with moisture leak rates .…”