Seminar: Profiling the Stresses in Shear Thickening Suspensions by Dr. Vikram Rathee

The Department of Physics, School of Natural Sciences, invites you to a seminar on 22nd May 2024, from 12 PM to 1 PM (IST) in B-219. The seminar will be presented by Dr. Vikram Rathee, Assistant Professor at the Department of Physics and Astrophysics, Delhi University. Dr. Rathee will discuss "Profiling the Stresses in Shear Thickening Suspensions," exploring the intriguing behavior of shear-thickening suspensions like cornstarch–water mixtures. This seminar promises to shed light on the fundamental and practical aspects of these suspensions, focusing on the role of the suspending fluid in the thickening transition. Abstract: The surprising behavior of shear-thickening suspensions, such as the familiar cornstarch–water mixture studied here, is of both fundamental and practical importance, but many aspects are not well understood, and in particular the role of the suspending fluid in the dramatic thickening transition remains elusive. Using direct measurements of spatially resolved surface stresses in the thickening regime, we have reported the existence of clearly defined dynamic localized regions of substantially increased stress that appear intermittently at stresses above the critical value [1]. In this talk, I will present the role of localized stress during shear thickening for different types of particles having varying size [2], shape [3], and surface properties [4]. We observed that the transition to thickening behavior can be driven by the proliferation of stable propagating fronts and we directly quantify the relative flow between the particulate phase and the suspending fluid, providing a quantitative measure of the concentration changes and internal pressure gradients associated with the thickening transition [5]. [References] V. Rathee, D. L. Blair, J. S. Urbach, Proceedings of National Academy of Sciences U.S.A. 114 (33), 8740-8745 (2017). V. Rathee, S. Arora, D. L. Blair, J. S. Urbach, A. K. Sood and R. Ganapathy, Phys. Rev. E 101, 040601(R) (2020). N. Park, V. Rathee, D. L. Blair, J. Conrad, Phy. Rev. Lett. 122, 228003 (2019). V. Rathee, A. Monti, M. Rosti, A. Shen; Soft Matter 17 (35), 8047-8058 (2021). V. Rathee, J. Miller, D. L. Blair, J. S. Urbach, Proceedings of National Academy of Sciences U.S.A. 119 (32) e2203795119 (2022).