Chem. Engg. Seminar Series : Manish Kumar

Turbulence in complex fluids

Abstract       :

Polymeric additives dramatically suppress inertial turbulence and hence reduce drag. Therefore, they are commonly used in pipeline transport of liquids to reduce pumping costs and in the filling of aircraft tanks to reduce fuel transfer time. They could also be used to save energy in the shipping industry, which has the major contribution to energy losses due to inertial turbulence. They have also been envisioned to enhance the drainage capacity of open flows to mitigate waterlogging and minimize the risk of flash floods. The emergence of elastoinertial turbulence (EIT), a type of turbulence in complex fluids, restricts the achievable drag reduction using polymer additives. In this talk, I will discuss the dynamics of EIT and demonstrate that its dynamics is predominantly composed of a collection of self-similar nested traveling waves, where the most dominant traveling wave originates from a nonlinear wall mode instability, and the remaining traveling waves originate from a recursive process. Due to its complexity, EIT is computationally expensive to investigate, creating a bottleneck in the downstream analyses of its dynamics. In the latter part of the talk, I will introduce a framework based on machine learning that enables the development of a reduced-order model of EIT, which accurately captures its dynamics roughly a million times faster than the direct numerical simulation. Such acceleration facilitates downstream analyses, including the investigation of coherent structures and the design of control strategies to suppress EIT to reduce turbulent drag beyond the Maximum Drag Reduction (MDR) limit.

Bio

Manish Kumar is an Assistant Professor in Chemical Engineering at the Indian Institute of Science and leads the Complex Fluids DS-CFD Lab. He received his Ph.D. in 2022 from Purdue University under the mentorship of Prof. Arezoo M. Ardekani and his B.Tech. in 2017 from the IIT Kharagpur where he worked with Prof. Suman Chakraborty. He completed his postdoctoral training with Prof. Michael Graham at UW-Madison. His research employs theoretical, computational, and data-driven approaches to investigate and manipulate the dynamics of complex fluids and soft materials relevant to energy, biomedical, and environmental applications. His research has been published in leading peer-reviewed journals, including PNAS, JFM, Soft Matter, and PRF. Several of his papers have been featured on journal covers, selected as Editor’s Picks, and highlighted in news articles. His selected honors include the Future of Rheology Excellent Speaker Award (2025), Trailblazers in Engineering Fellow (2024), Society of Engineering Science Future Faculty Award (2023), Society of Rheology Best Poster Award (2021), Ross Fellow (2017), Sikharini Nag Memorial Award (2017), and DAAD Fellow (2016).