講演者: Dr. Manoranjan Mishra (Asst. Prof.) Indian Institute of Technology, Ropar
講演題目：Hydrodynamical instability in miscible fluids system: Applications in liquid chromatography （混合流体における流体力学的不安定性 ～ 液体クロマトグラフィーへの応用）
When the viscosity of the sample injected in a liquid chromatographic (LC) column is different from that of the carrier liquid, a hydrodynamic instability occurs at that sample/carrier interface where the more viscous fluid is displaced by the less viscous one. The latter penetrates into the more viscous zone, forming some kind of fingers, which grow as they migrate, hence the name “viscous fingering” (VF) given to this instability. It is an interfacial hydrodynamical instability that occurs when a less viscous fluid displaces another more viscous miscible one in a porous medium, that appear in many other applications like microfluidic mixing, dispersion in aquifers etc. Such instability may cause a distortion of the peak shapes and, generally, a decrease in separation performances. Evidence of this phenomenon in present-day LC columns has been clearly provided by the in situ optical visualization experiments.
In this talk a computational study to explore the effect of the underlying physico-chemical phenomena, (i.e. the combined effects of solvent strength, retention and viscous fingering) on the dynamics of the adsorbed solute onto the porous matrix will be presented. The second part of the talk will be on the viscous fingering dynamics between partial miscible fluids. In such cases a steep concentration gradient exists between both the miscible fluids and that gives rise to an additional stress term in the momentum equation, called Korteweg stress. Such stresses mimic a surface tension type force, which may act against the growth of the instability in viscous fingering. A linear stability analysis has been presented here to study the onset of the fingering instability with and without Korteweg stresses and compared with the numerical simulation results.
Relevant publications of the speaker:
1. Pramanik, S. and Mishra, M. (2013) Linear Stability Analysis of Korteweg Stresses Effect on Miscible Viscous Fingering in Porous Media, Physics of Fluids, Vol 25, 074104.
2. Rana, C., De Wit, A., Martin, M. and Mishra, M., (2014) Combined influences of viscous fingering and solvent effect on the distribution of adsorbed solutes in porous media, RSC Advances, Vol. 4, PP 34369–3438.
3. Rana, C. and Mishra, M. (2014) Fingering dynamics on the adsorbed solute with less viscous strong sample solvent, The Journal of Chemical Physics, 141, 214701.
4. Pramanik, S. and Mishra, M. (2015) Nonlinear simulation of miscible viscous fingering with gradient stresses in porous media, Chemical Engineering Science 122, 523-532.
5. Pramanik, S. and Mishra, M. (2015), Viscosity scaling of fingering instability in finite slices with Korteweg stress. Europhysics letters (EPL), 109, 64001.
Dr. Manoranjan Mishra obtained his PhD from Indian Institute of Science (IISc), Bangalore in the year 2004. He carried out post-doctoral studies at Institute Non-linear de Nice, University of Nice-Sophia Antipolis, France (2005-2006) obtaining a fellowship from French National Ministry of Education and Research. Further he did postdoctoral research at Université Libre de Bruxelles, Belgium during 2006-2007 under the Action de Recherches Concertées ARCHIMEDES Programme. He has been a recipient of Humboldt fellowship of Alexander von Humboldt Foundation (AvH), Germany during 2007-2008 and did work at, Univeristy of Erlangen-Nurnberg, Germany. Also he received FRS-FNRS fellowship from Fonds de la Recherche Scientifique, Belgium in 2008-2009 to work at Université Libre de Bruxelles, Belgium. Since February 2010, he is an Assistant Professor at the Department of Mathematics, Indian Institute of Technology Ropar.