Capillary filling dynamics of viscoelastic fluids

Abstract

We consider the filling of a capillary by a viscoelastic fluid described by the Phan-Thien-Tanner (PTT) constitutive behavior. By considering both vertical capillary filling and horizontal capillary filling, we demarcate the role played by gravity and fluid rheology towards long-time oscillations in the capillary penetration depth. We also consider the isothermal filling of the capillary for a closed channel and thus bring out the fundamental differences in the nature of capillary filling for PTT and Newtonian fluids for closed channels in comparison to open channels. Through a scaling analysis, we highlight a distinct viscoelastic regime in the horizontal capillary filling which is in contrast to the Washburn scaling seen in the case of Newtonian fluids. Such an analysis with a very general constitutive behavior is therefore expected to shed light on many areas of microfluidics which focus on biofluids that are often well described by the PTT constitutive behavior.

Investigation of the effects of time periodic pressure and potential gradients on viscoelastic fluid flow in circular narrow confinements

“…The findings advance our understanding of time periodic electrokinetic phenomena of viscoelastic fluids and provide (Nguyen et al 2013). Chakraborty and colleagues have theoretically studied transport of non-Newtonian fluid (inelastic power law fluids and recently viscoelastic constitutions) using separately steady PDF (Bandopadhyay and Chakraborty 2011), steady EOF (Chakraborty 2007;Ghosh and Chakraborty 2015), time periodic PDF (Bandopadhyay and Chakraborty 2012a, b;Bandopadhyay et al 2014) and time periodic EOF (Bandopadhyay et al 2013) in rectangular narrow confinements. Afonso et al studied the combined steady PDF and EOF using two different viscoelastic fluid models, namely the Phan-Thien-Tanner (PTT) model and the finitely extensible nonlinear elastic with a Peterlin approximation (FENE-P) model (Afonso et al 2009).…”

Contact line dynamics of electroosmotic flows of incompressible binary fluid system with density and viscosity contrasts

“…25 In recent studies, different aspects of contact line motion, like relevant scales, different regimes, dynamical transitions, and their influence over the capillary filing dynamics, have been discussed comprehensively. [26][27][28] Of late, electrically actuated flows through narrow confinements have gained prominence primarily due to its wide spectrum of important applications. [29][30][31][32][33][34][35][36] Such flows may come about by the movement of a charged layer of fluid (also known as Electric Double layer or, EDL) adjacent to a solid surface in presence of an external electric field.…”

Effect of intrinsic angular momentum in the capillary filling dynamics of viscous fluids

“…The increase in viscosity using molecular fluids resulted in faster development from inertia to the pure viscous regime. Furthermore, it was found that the fluid requires less time to reach the maximum viscous force as the channel height increased which is similar to the capillary filling dynamics of viscoelastic fluids [30]. Lastly, the behavior of front position length was mostly affected by the spin viscosity in the third viscous-dominated region.…”

“…(13) by integrating it twice with zero boundary condition as [30]: (14) In the next section, different regimes for the capillary filling dynamics will be discussed.…”