Droplet formation – a numerical investigation of liquid-liquid systems with consideration of Marangoni convection

Understanding the Effects of Physical Properties of Composite Drop on its Formation Dynamics in Presence of Interfacial Mass Transfer

“…Specifically, the complexity lies in resolving the coupling of velocity and concentration fields accurately, obtained as solutions of flow field and mass transfer conservation equations, along with capturing the dynamic evolution of the liquid–liquid interface. Thus, we find a very few attempts in the recent past, employing the assumptions of axisymmetric drop shape and constant physical properties except interfacial tension in the numerical simulations. ,,, However, the relation between solute concentration and interfacial tension is entirely based on empirical correlations, involving the time-averaged interfacial tension. , Presently, a method to accurately measure the interfacial tension gradient and solute concentration along the evolving interface during drop formation at a submerged location in continuous phase is not available, and it can be a subject of investigation for liquid−liquid extraction systems. In view of these difficulties, we have not conducted numerical simulations for the multiple systems explored in this work.…”

“…Thus, we find a very few attempts in the recent past, employing the assumptions of axisymmetric drop shape and constant physical properties except interfacial tension in the numerical simulations. 20,21,62,63 However, the relation between solute concentration and interfacial tension is entirely based on empirical correlations, involving the time- averaged interfacial tension. 20,23 Presently, a method to accurately measure the interfacial tension gradient and solute concentration along the evolving interface during drop formation at a submerged location in continuous phase is not available, and it can be a subject of investigation for liquid−liquid extraction systems.…”

“…Previously, it has been shown that 10–50% − and even 80% of the overall mass transfer occurs during drop formation, due to the very high concentration gradient in this stage. Thus, with the aim of evaluating early-stage mass transfer coefficient, the formation of a single drop has been studied by a few authors, using experiments, − analytical models, − and recently, numerical simulations. − …”

Dynamics of Drop Formation in the Presence of Interfacial Mass Transfer

“…For example, at a higher nozzle Reynolds number ( Re N > 10), the model predictions by Walia and Vir deviate from the experimental data of Liang and Slater . These model predictions were based on various assumptions concerning the local dynamics of fluid flow, namely, surface renewal rate, boundary curvature, internal mixing, etc., whereas experimental approaches were based on concentration measurements at the end of the drop formation lifetime. ,,, The literature reported in last 2 decades conclude that the Marangoni convection promotes the surface renewal rate and, thus, contributes to the enhancement in mass transfer. – However, the transient Marangoni convection and its implication on real-time dynamics of drop formation are not reported in the literature. Although the liquid–liquid extraction has been under practice for a long time in different industries, viz., nuclear, chemical, pharmaceutical, petrochemical, etc., the designs of extractors are mainly based on empirical correlations and pilot scale experiment .…”