(6es) Complex Interfacial Dynamics, Deformation-Based Microrheology, and Beyond

Advances in visualization and manipulation over length scales ranging from the molecular to the macroscopic have ushered a need and relevance in connecting the structure, flow, and rheology of soft materials with applications in materials design and micro-scale/biological transport. I intend to look at these critical questions through the lens of microhydrodynamics, while providing the soft matter community with insights into designing new experiments, materials, and measurement techniques.

As a doctoral student with David Saintillan at the University of Illinois at Urbana-Champaign and later at the University of California, San Diego, I developed a theoretical and numerical framework to study the hydrodynamics of elastic filaments such as stiff biopolymers and fibers. I applied this model to illustrate unique instabilities and shape transitions of elastic biopolymers in microfluidic devices, and describe, for the first time, the effect of particle flexibility on suspension stability.

More recently, as a postdoctoral researcher with Todd Squires at the University of California, Santa Barbara, I have focused on the dynamics of complex surfactant-laden interfaces, such as in membranes, industrial coatings, and biological interfaces like lung alveoli. My theoretical work has revealed qualitatively new features such as non-intuitive pair interactions between interfacial probes, spurring new directions of experimental investigation with far-reaching consequences in the measurement and interpretation of interfacial rheology.

Recent theoretical work and its broader consequences in ‘2D suspensions’ will be the focus of my oral presentation at this meeting.

Selected Publications:

H. Manikantan & T. M. Squires, Proceedings of the Royal Society A 473, 0346 (2017).
H. Manikantan & T. M. Squires, Physical Review Fluids 2, 023301 (2017).
H. Manikantan & D. Saintillan, Physics of Fluids 28, 013303 (2016).
H. Manikantan & D. Saintillan, Physical Review E 92, 041002 (2015).
H. Manikantan, L. Li, S. E. Spagnolie & D. Saintillan, Journal of Fluid Mechanics 756, 735-764 (2014).
L. Li, H. Manikantan, D. Saintillan & S. E. Spagnolie, Journal of Fluid Mechanics 735, 705-736 (2013).
H. Manikantan & D. Saintillan, Physics of Fluids 25, 073603 (2013).

Research Interests:

Moving forward, my research will involve mathematical modeling, numerical simulations, and lab experiments in close collaboration with other researchers to understand complex soft systems. A primary area of interest will be fluid-fluid interfaces populated with surfactants, proteins, particles, or macromolecules. The subtle interplay of surface rheology, Marangoni stresses, adsorption/desorption, and 2D phase behavior makes complex interfaces as rich a field of exploration and relevance as traditional 3D fluids. Teasing apart these different phenomena in real examples using analytical theory will be a central theme of my work. These studies will also advise new avenues and model problems for collaborative experiments and ultimately guide better prediction and design. Armed with these fundamental insights, my vision is to explore more involved and applied problems such as the collective motion and assembly of surface aggregates, lipid domains, and surface-attached probes.

Another broad avenue of research will be the fluid-structure interaction of deformable inclusions, and its interplay with bulk rheology. Elongated elastic particles such as actin and microtubules occur in nature as a way to provide locomotive and structural properties to cellular systems. Internal degrees of freedom of particles embedded in a medium can relax stresses, and in turn contribute to the bulk behavior of the material. I will focus on elucidating the impact of shapes and deflections of suspended elastic particles on effective rheology, and developing a deformation-based mathematical framework for nonlinear microrheology with exciting experimental opportunities. I will also explore related themes in the hydrodynamic ‘training’ and ‘healing’ of biopolymers for cellular functions, and in assembling artificial micro-structures.

Teaching Interests:

I am committed to being an effective and engaging teacher, and have been recognized with teaching awards and certifications from both the University of Illinois at Urbana-Champaign and the University of California, San Diego. I strive to provide a solid foundation in the mathematical and physical principles, while connecting concepts to real applications. I also make it a point to encourage participation and communication, while continually collecting and acting on student feedback. I have been a teaching assistant in four undergraduate and two graduate classes, through which I have practiced and implemented my teaching strategies, with student ratings that reflect the success of my methods. I have a particular interest in teaching foundational undergraduate and graduate courses in transport phenomena, biophysics, and mathematical methods, and specialized courses in soft matter, colloids and suspensions, and microhydrodynamics. Beyond college-level teaching, I have also independently designed and delivered two high-school-level courses, with excellent feedback on both.