I have been interested in microscale effects on the bulk response of materials. Most materials have features at smaller length scales which affect their mechanical behaviour. However, models which incorporate such microscale effects are only recently being developed. The problems I have been working on fall into three main areas:

Microstructure Evolution

  1. Polycrsytalline grain growth
  2. I have used phase field models to study the kinetics of polycrystalline grain growth in the presence of mobile second phase particles. Currently, we are working on incorporating grain rotation into phase field models as well as studying recrystallization kinetics and modeling grain boundary engineering.

  3. Solid-solid transformations in shape memory alloys
  4. The kinetics of twin boundary motion show stick slip behaviour which originates from lattice vibrations. Discrete models and phase field approaches have proved useful to study such kinetics and the effect on mechanical behaviour of shape memory alloys.

Microfluidics

We have been modeling the fluid flow in microchannels using Dissipative Particle Dynamics. In collaboration with Prof. BSV Patnaik we have developed new approaches of incorporating boundary conditions in DPD to minimize density fluctuations at walls and also studied the effect of finite slip boundary conditions on flow in microchannels. We have used a particular configuration to model separation of DNA strands of different lengths in straight microchannels.

Short Polymer animation Long Polymer animation

Granular Slurries

In collaboration with Prof. Mahesh Panchagnula, we have been modelling flow of wet granular slurries in a square cavity. Our model of the slurry is novel (Granular Matter, 2015) and applicable to cases in which the fluid inertia is small relative to the particle inertia in any representative area element. The video below shows how mixing of the granular slurry happens in the square cavity driven by a belt at the bottom. The belt is moving to the right and a value of a mixing parameter is being tracked in the figure on the right.

Wetting of surfaces by sessile drops