We are pleased to announce that Somnath Bhattacharyya, professor at the Indian Institute of Technology Kharagpur (India), will give the SFB 1313 "Pretty Porous Science Lecture" #60. His talk will be on "Recent advancement on mean-field based theory of microfluidic transport process".
Date: 19 December 2024
Time: 11 am CET
Speaker: Prof. Somnath Bhattacharyya, Indian Institute of Technology Kharagpur (India)
Title: Recent advancement on mean-field based theory of microfluidic transport process
Venue: ITLR, seminar room 31.103
Abstract
Micro- and Nanofluidics has established itself as a new field in fluid mechanics, which involves the electrokinetic transport phenomena linked with the movement of an ionized solution near a charged interface. The well-established mean-field based approach for transport of ionic solutions considers the long-range Columbic interactions between the ions. Under the mean-field consideration the distribution of discrete ions in the media is expressed by the average ionic concentration, which is governed by the ion transport equation. The classical Nernst-Planck equation to describe the transport of each ionic species under the mean-field consideration is based on conservation principle of mass flux in which ions are treated as point charge. This leads to a non-linear partial differential equation coupled with the equation for fluid flow i.e., the Navier-Stokes equations and the Poisson equation for the electric field. These models (PNP-model) qualitatively as well as quantitatively describe several electrokinetic transport phenomena observed experimentally. In this model, the ion-solvent interaction is neglected. The dielectric permittivity and the viscosity of the medium are generally considered as independent of the local ion concertation. The PNP-model breaks down when the crowding of ions becomes significant. The missing mechanisms have not yet been identified despite abundant evidences from both experiments and atomic simulations indicating the classical electrokinetic theory being not sufficient to describe physical phenomena at the nanoscale. The mean-field approach may no longer be valid for a larger density of ions in EDL and the many-body dynamics needs to be adopted to account the correlations between discrete ions. In this talk an outline on improved microfluidic transport model will be discussed. Based on the continuum hypothesis, a mathematical model is developed to incorporate the ion-ion correlations on the electrophoresis of a highly charged soft particle. The ions are considered to be of finite size, which create a hydrodynamic steric interaction and the viscosity of the suspension medium to vary with the local ionic volume fraction. The dielectric permittivity of the medium is considered to depend on the local ionic concentration, which arises due to the formation of a hydration shell around the electrolyte ions.