Virtual Seminar"Analysis of Thixotropy"Yogesh M Joshi

Micro/Bio/Nanofluidics (Shen) Unit would like to invite you to the virtual seminar by Prof. Yogesh M Joshi on March 22 (Tuesday).
 
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Date: Tuesday, March 22, 2022
Time: 16:00-17:00
**Zoom session
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*Zoom information

Join Zoom Meeting
https://oist.zoom.us/j/97586560819?pwd=d3I1QzJ2T2RnbGR3eEErYkF5OUNVZz09

Meeting ID: 975 8656 0819
Passcode: 104459

Speaker:

Yogesh M Joshi
Professor
Department of Chemical Engineering
Indian Institute of Technology Kanpur
Kanpur INDIA.

Title:

Analysis of Thixotropy

Abstract:

Thixotropy concerns the microstructural evolution of a soft material under quiescent or weak flow conditions, causing a time-dependent increase in the viscosity; and destruction of the evolved microstructure under strong flow conditions leading to a time-dependent decrease in the viscosity. However, due to non-linear viscoelasticity, materials often show characteristic features resembling thixotropy. This issue has been debated in the literature over the past several decades, and many experimental protocols have been proposed to distinguish thixotropy from viscoelasticity. In the first part of the talk, we assess these methods using non-linear viscoelastic as well as standard thixotropic models and propose a robust criterion to distinguish these two properties. Furthermore, the real thixotropic materials undergo enhancement in elastic modulus with time and decrease in the same under application of deformation field. Incorporation of this feature in a viscoelastic structural kinetic model can possibly violate the second law of thermodynamics. Furthermore, in a related experimental observation, stress has been reported to undergo a nonmonotonic change as a function of time under the application of constant strain. In the second part of the talk, we analyze these scenarios and propose a model formulation that prevents violation of the second law.

Biography:

Dr Yogesh Joshi did B.E. in Polymer Engineering from Pune University in 1996 and PhD in Chemical Engineering from Indian Institute of Technology Bombay in 2001. Subsequently, he joined Benjamin Levich Institute, New York for post-doctoral studies. Dr Joshi joined Department of Chemical Engineering, Indian Institute of Technology Kanpur in 2004, where presently he is a Pandit Girish & Sushma Rani Pathak Chair Professor and the Dean of International Relations. His research interests include rheology of complex fluids, colloidal glasses and gels and phase behavior of clay dispersions. Dr Joshi is a senior editor of Langmuir, and on the editorial board of Journal of Rheology, Rheologica Acta and Physics of Fluids. Dr Joshi is an elected fellow of the Indian National Academy of Engineering (2016) and the National Academy of Sciences, India (2017). He is also closely associated with many industries pertaining to improving the flow behavior and stability of soft materials.

Host:

Prof. Amy Shen