Research Interests
Study of dense granular materials
A granular material can be defined as any material composed of many individual solid particles, regardless of particle size. Thus, the term granular material consists of various materials, from the coarsest rubbles to the finest icing sugar or talcum powder. Handling granular materials is of the greatest importance in the chemical industry. Granular materials are also called bulk solids. Knowledge of the stress profile in static columns is useful in designing bins and bunkers for storing food grains, cement, mineral ores and other granular materials. Granular materials are also continuously sheared in various industrial processes, such as pneumatic transportation, emptying of bins, and mixing; hence, understanding the stress during flow is important. Despite its importance, the stress behaviour during shear is poorly understood, as the rheology of granular materials is complex. In this project, we will study granular materials' stress distribution and bulk rheology using a rheometer and then develop a theoretical model to predict its dynamics.
Rheologial properties of the Particulate suspension
Particulate Suspensions, comprising solid particles dispersed in a fluid medium, are widespread in industries. Common examples are slurries, pastes, composite materials, ceramics, colloids, polymers etc. A complete understanding of their rheology is required to manufacture, process and transport these materials. Recent studies have proved that flowing suspensions exhibit non-Newtonian characteristics, even when the suspending fluid is Newtonian. Models assuming Newtonian behaviour of suspensions fail to explain some interesting phenomena exhibited by these suspensions. Shear-induced migration is one example that has received wide attention: In certain inhomogeneous shear flows of non-colloidal suspensions, particles irreversibly migrate to yield highly nonuniform con-centre fields. This project will examine the rheology, microstructure and particle motion in suspensions of soft and rigid particles of different shapes in Newtonian and Non-Newtonian fluids.
Rheologial properties of the epithelial cells
The cells are active material with fascinating mechanical properties because they can remodel their cytoskeleton to undergo migration, division, expansion, contraction and spread. The major portion of the energy required for this remodelling comes from the serum present in the culture medium. However, the effect of serum starvation on the mechanical properties of monolayer has not been explored. Therefore, this work aimed to investigate the effect of serum on the rheological properties of the epithelial monolayer. Here, we are performing the bulk shear rheology of the continuous epithelial monolayer (Fig. A) and observing its mechanical properties as a function of living activity (Fig. B).
Mechanism of collective cell migration
The mechanism of single-cell migration is well-known. However, the mechanism responsible for collective cell migration is unknown. In this work, we aim to identify the novel physical mechanism through which multiple cell rows communicate to achieve collective cell migration in the freely expanding monolayer (Fig. A). Further, we aim to investigate the effect of initial boundary conditions on the collective cell migration (Fig. B).
Fluctuation dynamics of the epithelial cell monolayer
Epithelial cell monolayer growth occurs in tissue development, wound healing, cancer metastasis, homeostasis, and other biological processes. Two types of fluctuations are observed in the growing epithelial cell monolayer: fluctuation in individual cell areas and fluctuations in cell number density. The area fluctuations could be related to the forces experienced by each cell through cell-ECM and cell-cell interactions. With the help of live-cell imaging experiments of epithelial cell monolayer, we intend to study the dynamics of the epithelial cell monolayer. This study aims to investigate the cell dynamics in a monolayer due to the combined active and passive fluctuations.
Collective Dynamics of Biologically Active Particles
Active fluids have recently garnered significant interest in the scientific community due to their complex behavior and the potential for innovative engineering applications. An "active fluid" comprises an ensemble of macromolecules, particles, cells, organisms, or fish suspended in a fluid, capable of converting chemical energy into mechanical work. These active fluids are out-of-equilibrium systems, experiencing continuous energy dissipation by the constituent particles. They represent a rich class of complex behavior that differs significantly from passive systems. Active suspensions find numerous applications in biophysics, targeted drug delivery, and ecological sciences. The collective behavior of organisms is linked to the self-propulsion of entities such as bacterial suspensions, algal suspensions, or schools of fish. At the individual level, organisms employ various propulsion mechanisms, such as the flagella of biflagellates (Chlamydomonas nivalis), spermatozoa, cilia of Paramecium, and more. In large numbers, individual organisms tend to align their orientation and synchronize their movements, giving rise to various spatio-temporal patterns. This phenomenon is also referred to as collective motion or swarms of a large number of self-propelled organisms. The collective motion of these organisms exhibits intriguing spatial and temporal patterns. In our lab, we study vinegar eels (Turbatrix aceti), nematodes approximately 2 mm in length and 50 μm in diameter. These nematodes thrive in high pH environments, such as vinegar, and are typically cultured for use as fish food. In our laboratory, we investigate the collective swimming dynamics of these nematodes, modeling them as "active fibers."
We also study the collective dynamics of Paramecium which are unicellular cilliates and commonly found in water bodies such as rivers, ponds and lakes.
Paramecium
