- Granular Solids
The mixing of granular solids is of considerable
importance for a large number of industrial applications (mixing of pharmaceuticals,
cement manufacture, etc.) yet it is poorly understood from a fundamental viewpoint.
One of the complicating factors is simultaneous segregation due to differences in particle
characteristics. Our work has focused on simple prototype mixers (rotating cylinders)
to gain an insight into the fundamental physics for the case of dry granular materials.
We are currently applying some of the basics to the understanding of calcination and
clinker formation in rotary kilns.
- Rodlike polymers
Rodlike polymers can be spun into ultra high
strength fibres (e.g. Kevlar) which find application in the manufacture of cables,
tyre cord, reinforcement for composites, bullet-proof fabrics, etc. Due to their
anisotropic shape such polymers are easily oriented by shear fields. We are
investigating the effect of such orienting fields applied during polymerization,
by means of experiment, theory and Brownian dynamics simulations.
- Polyurethane foams
Polyurethane foams are made by the polymerization
of polyols with di-isocyanates with simultaneous gas generation. Applications are widespread
and include thermal isulation and cushioning. The aim of our studies is to a obtain an understanding
of the effect of formulation and processing conditions on the dynamics of formation, structure and
final properties of free rise and moulded foams
- U. S. Agarwal, and D. V. Khakhar, Enhancement of
polymerization rates of rodlike molecules by shearing, Nature, 360, 53-55 (1992).
- G. O. Fountain, D. V. Khakhar and J. M. Ottino,
Visualization of three-dimensional chaos, Science, 281, 683-686, (1998).
- A. Swaminathan and D. V. Khakhar,
Rigid polyurethane foams for buoyancy applications: Hydraulic resistance,
Cellular Polym,19, 1-11, (2000).
- A. Agge, S. Jain and D. V. Khakhar,
Acceleration of polymerization of rodlike molecules by flow, J. Am. Chem. Soc., 122, 10910-10913(2000).
- A. V. Orpe, and D. V. Khakhar, Scaling relations
for granular flow in quasi-two-dimensional rotating cylinders, Phys. Rev. E, 64, 031302 (2001).
- D. V. Khakhar, A. V. Orpe and S. K. Hajra,
Segregation of granular materials in rotating cylinders, Physica A, 318, 129-136, (2003).
- A. V. Orpe, and D. V. Khakhar, Solid-liquid transition
in a granular shear flow, Phys. Rev. Lett., 93, 068001 (2004).
- S. K. Hajra and D. V. Khakhar, Radial mixing of granular
materials in a rotating cylinder: Experimental determination of particle self-diffusivity,
Phys. Fluids, 17, 013101 (2005).
- P. Mondal and D. V. Khakhar, Simulation of the
percolation of water into rigid polyurethane foams at applied hydraulic pressures,
Polym. Eng. Sci., 46, 970-983 (2006).
- A. V. Orpe and D. V. Khakhar, Rheology of surface
granular flows, J. Fluid Mech., 571, 1-32 (2007).