About me

Ashwin Joy
Ph.D., Institute for Plasma Research, Gandhinagar.

Broad area of interest:
Hydrodynamics, Soft Condensed Matter and Statistical Physics.

Ph.D work

Two dimensional (2D) Turbulence
As is well known, fluid turbulence is ubiquitous in nature. One can observe turbulent mixing in liquids at the widest possible length scales ranging from a coffee cup to the universe. Although in real life scenarios turbulent phenomena are known to be three dimensional (3D) in nature, two dimensional (2D) turbulence, however, has the special distinction that it is realized only in computer simulations and laboratory experiments under certain ideal conditions (e.g. rotation driven azimuthal symmetry). Nevertheless, 2D turbulence serves an invaluable starting point for modeling geophysical phenomena in the atmosphere, oceans, magnetosphere and thermo-nuclear plasma in tokomaks, to name a few. A remarkable property of 2D turbulence is the spontaneous emergence of isolated coherent structures, a subject studied in great detail through both numerical methods and laboratory experiments on rotating liquids.

Strongly coupled liquids
Unlike ordinary liquids, strongly coupled liquids are systems where the average potential energy per particle dominates the average kinetic energy (e.g. complex plasma, liquid metals or even white dwarfs) thereby rendering a theoretical description possible, only by approximate methods.

Coherent structures in strongly coupled liquids
Taking the Yukawa liquid as a prototype model, we have reported for the first time, the emergence of isolated coherent tripolar vortices in 2D strongly coupled liquids through ``first principle'' molecular dynamics (MD) simulations [4]. These tripolar vortices survive over several eddy turn over times and their dynamics explored at various values of coupling strength. My research expands the possibility of observing such tripolar vortices in laboratory experiments on strongly coupled liquids such as complex plasmas, condensed matter systems and possibly in astrophysical systems like white dwarfs and neutron stars.

Publications

[1] "Formation and interaction of dipolar vortices in strongly coupled liquids"
Ashwin J. and R. Ganesh,
(Under Review)

[2] "Coevolution of inverse cascade and nonlinear heat front in shear flows of strongly coupled Yukawa liquids",
Ashwin J. and R. Ganesh,
Physics of Plasmas (18), 083704 (2011) [Abstract]

[3] "Coherent Vortices in Strongly Coupled Liquids",
Ashwin J. and R. Ganesh,
Physical Review Letters (106), 135001 (2011) [Abstract]

[4] "Parallel shear instabilities in strongly coupled Yukawa liquids: A comparison of generalized hydrodynamic model and molecular dynamics results",
Ashwin J. and R. Ganesh,
Physics of Plasmas (17), 103706 (2010) [Abstract]

[5] "Kelvin Helmholtz instability in Strongly Coupled Yukawa Liquids",
Ashwin J. and R. Ganesh,
Physical Review Letters (104), 215003 (2010) [Abstract]

[6] "Effect of external drive in strongly coupled Yukawa systems: A non-equilibrium molecular dynamics study",
Ashwin J. and R. Ganesh,
Physical Review E (80), 056408 (2009) [Abstract]

Codes written

1.) MPMD (Multipotential molecular dynamics) code: A massively parallel MPI based parallel molecular dynamics code written in standard C programming language.

2.) MPMD PyUtils A toolkit containing several python, scipy and matplotlib based utilities for numerical post-processing of MPMD data.

3.) SG-Hydro (Screened generalized hydrodynamic) code: A massively parallel MPI based pseudo-spectral code designed to model turbulence in a screened generalized hydrodynamic model. The code is written in C and parallel Fourier transforms are implemented using FFTW library to achieve performance.

Contact

Ashwin Joy
Institute for Plasma Research,
Bhat-Village, Gandhinagar-382428,
Gujarat, India.
Tel : +91-79-23962031
E-mail : ashwin<AT>ipr<DOT>res<DOT>in