Instabilities and waves in thin films of living fluids (2008)
Sankararaman, Sumithra, Ramaswamy, Sriram
We formulate the thin-film hydrodynamics of a suspension of polar self-driven particles and show that it is prone to several instabilities through the interplay of activity, polarity and the...
Active elastic dimers: Self-propulsion and current reversal on a featureless track (2008)
Vijay Kumar, K., Ramaswamy, Sriram, Rao, Madan
Open Access
Universality Class of the Reversible-Irreversible Transition in Sheared Suspensions (2008)
Menon, Gautam I., Ramaswamy, Sriram
Collections of non-Brownian particles suspended in a viscous fluid and subjected to oscillatory shear at very low Reynolds number have recently been shown to exhibit a remarkable dynamical phase...
Active elastic dimers: Self-propulsion and current reversal on a featureless track (2008)
Kumar, Vijay K, Ramaswamy, Sriram, Rao, Madan
We present a Brownian inchworm model of a self-propelled elastic dimer in the absence of an external potential. Nonequilibrium noise together with a stretch-dependent damping form the propulsion...
Active elastic dimers: Self-propulsion and current reversal on a featureless track (2008)
Kumar, Vijay K, Ramaswamy, Sriram, Rao, Madan
We present a Brownian inchworm model of a self-propelled elastic dimer in the absence of an external potential. Nonequilibrium noise together with a stretch-dependent damping form the propulsion...
Basu, Abhik, Ramaswamy, Sriram
We analyse the field theory for the dissipative dynamics of interacting inertialess particles, using a dynamic density-wave model (Bagchi 1987 Physica A 145 273), including thermal fluctuations (Dean...
Active elastic dimers: self-propulsion and current reversal on a featureless track (2007)
Kumar, K. Vijay, Ramaswamy, Sriram, Rao, Madan
We present a Brownian inchworm model of a self-propelled elastic dimer in the absence of an external potential. Nonequilibrium noise together with a stretch-dependent damping form the propulsion...
Ramaswamy, Sriram, Simha, Aditi R
This articles reviews briefly our recent theoretical results on order, fluctuations and flow in collections of self-driven particles, in suspension or on a solid surface. The theoretical approach we...
Active-filament hydrodynamics: instabilities, boundary conditions and rheology (2007)
This paper studies several issues that emerge naturally in the hydrodynamic approach to suspensions of self-driven organisms or filaments (Simha and Ramaswamy 2002 Phys. Rev. Lett. 89 058101; Kruse...
Basu, Abhik, Ramaswamy, Sriram
We analyse the field theory for the dissipative dynamics of interacting inertialess particles, using a dynamic density-wave model (Bagchi 1987 Physica A 145 273), including thermal fluctuations (Dean...
Basu, Abhik, Ramaswamy, Sriram
We analyse the field theory for the dissipative dynamics of interacting inertialess particles, using a dynamic density-wave model (Bagchi 1987 Physica A 145 273), including thermal fluctuations (Dean...
Active-filament hydrodynamics: instabilities, boundary conditions and rheology (2007)
This paper studies several issues that emerge naturally in the hydrodynamic approach to suspensions of self-driven organisms or filaments (Simha and Ramaswamy 2002 Phys. Rev. Lett. 89 058101; Kruse...
Long-lived Giant Number Fluctuations in a Swarming Granular Nematic (2006)
Narayan, Vijay, Ramaswamy, Sriram, Menon, Narayanan
Coherently moving flocks of birds, beasts or bacteria are examples of living matter with spontaneous orientational order. How do these systems differ from thermal equilibrium systems with such...
Shear flow induced isotropic to nematic transition in a suspension of active filaments (2006)
Muhuri, Sudipto, Rao, Madan, Ramaswamy, Sriram
We study the effects of externally applied shear flow on a model of suspensions of motors and filaments, via the equations of active hydrodynamics [PRL {\bf 89} (2002) 058101; {\bf 92} (2004)...
Ramaswamy, Sriram, Simha, Aditi R
This articles reviews briefly our recent theoretical results on order, fluctuations and flow in collections of self-driven particles, in suspension or on a solid surface. The theoretical approach we...
Do Current-Density Nonlinearities Cut Off the Glass Transition? (2006)
Extended mode-coupling theories for dense fluids predict that nonlinear current-density couplings cut off the singular "ideal glass transition" present in the standard mode-coupling theory where such...
Active nematics are intrinsically phase-separated (2006)
Mishra, Shradha, Ramaswamy, Sriram
Two-dimensional nonequilibrium nematic steady states, as found in agitated granular-rod monolayers or films of orientable amoeboid cells, were predicted [Europhys. Lett. {\bf 62} (2003) 196] to have...
Do Current-Density Nonlinearities Cut Off the Glass Transition? (2006)
Extended mode-coupling theories for dense fluids predict that nonlinear current-density couplings cut off the singular "ideal glass transition" present in the standard mode-coupling theory where such...
Ramaswamy, Sriram, Simha, Aditi R
This articles reviews briefly our recent theoretical results on order, fluctuations and flow in collections of self-driven particles, in suspension or on a solid surface. The theoretical approach we...
Do current-density nonlinearities cut off the glass transition? (2005)
Cates, M. E., Ramaswamy, Sriram
Extended mode coupling theories for dense fluids predict that nonlinear current-density couplings cut off the singular `ideal glass transition', present in the standard mode coupling theory where...
Narayan, Vijay, Menon, Narayanan, Ramaswamy, Sriram
We study experimentally the nonequilibrium phase behaviour of a horizontal monolayer of macroscopic rods. The motion of the rods in two dimensions is driven by vibrations in the vertical direction....
Hydrodynamics and phases of flocks (2005)
Toner, John, Tu, Yuhai, Ramaswamy, Sriram
We review the past decade's theoretical and experimental studies of flocking: the collective, coherent motion of large numbers of self-propelled "particles" (usually, but not always, living...
Flow-induced currents in nanotubes: a Brownian dynamics approach (2005)
Das, Moumita, Ramaswamy, Sriram, Sood, A. K., Ananthakrishna, G.
Motivated by recent experiments [Science {\bf 299}, 1042 (2003)] reporting that carbon nanotubes immersed in a flowing fluid displayed an electric current and voltage, we numerically study the...
Routes to spatiotemporal chaos in the rheology of nematogenic fluids (2005)
Das, Moumita, Chakrabarti, Buddhapriya, Dasgupta, Chandan, Ramaswamy, Sriram, Sood, AK
With a view to understanding the rheochaos observed in recent experiments in a variety of orientable fluids, we study numerically the equations of motion of the spatiotemporal evolution of the...
Hydrodynamics and phases of flocks (2005)
Toner, John, Tu, Yuhai, Ramaswamy, Sriram
We review the past decade's theoretical and experimental studies of flocking: the collective, coherent motion of large numbers of self-propelled "particles" (usually, but not always, living...
Narayan, Vijay, Menon, Narayanan, Ramaswamy, Sriram
We study experimentally the nonequilibrium phase behaviour of a horizontal monolayer of macroscopic rods. The motion of the rods in two dimensions is driven by vibrations in the vertical direction....
Routes to spatiotemporal chaos in the rheology of nematogenic fluids (2005)
Das, Moumita, Chakrabarti, Buddhapriya, Dasgupta, Chandan, Ramaswamy, Sriram, Sood, AK
With a view to understanding the rheochaos observed in recent experiments in a variety of orientable fluids, we study numerically the equations of motion of the spatiotemporal evolution of the...
Narayan, Vijay, Menon, Narayanan, Ramaswamy, Sriram
We study experimentally the nonequilibrium phase behaviour of a horizontal monolayer of macroscopic rods. The motion of the rods in two dimensions is driven by vibrations in the vertical direction....
Routes to spatiotemporal chaos in the rheology of nematogenic fluids (2004)
Das, Moumita, Chakrabarti, Buddhapriya, Dasgupta, Chandan, Ramaswamy, Sriram, Sood, A. K.
With a view to understanding the ``rheochaos'' observed in recent experiments in a variety of orientable fluids, we study numerically the equations of motion of the spatiotemporal evolution of the...
Nonequilibrium steady states of the isotropic classical magnet (2004)
Das, Jayajit, Rao, Madan, Ramaswamy, Sriram
We drive a d-dimensional Heisenberg magnet using a spatially anisotropic current of mobile particles or heat. The continuum Langevin equation is analyzed using a dynamical renormalization group,...
Rheology of active-particle suspensions (2004)
Hatwalne, Yashodhan, Ramaswamy, Sriram, Rao, Madan, Simha, R Aditi
We study the interplay of activity, order, and flow through a set of coarse-grained equations governing the hydrodynamic velocity, concentration, and stress fields in a suspension of active,...
Spatiotemporal Rheochaos in Nematic Hydrodynamics (2004)
Chakrabarti, Buddhapriya, Das, Moumita, Dasgupta, Chandan, Ramaswamy, Sriram, Sood, AK
Motivated by recent observations of rheochaos in sheared wormlike micelles, we study the coupled nonlinear partial differential equations for the hydrodynamic velocity and order-parameter fields in a...
Spatiotemporal Rheochaos in Nematic Hydrodynamics (2004)
Chakrabarti, Buddhapriya, Das, Moumita, Dasgupta, Chandan, Ramaswamy, Sriram, Sood, AK
Motivated by recent observations of rheochaos in sheared wormlike micelles, we study the coupled nonlinear partial differential equations for the hydrodynamic velocity and order-parameter fields in a...
The segregation instability of a sheared suspension film (2003)
Govindarajan, Rama, Nott, Prabhu R., Ramaswamy, Sriram
Starting from the equations of Stokes flow and the mass conservation of particles as determined by shear-induced diffusion, we derive the coupled equations for the dynamics of particle concentration...
Collective stochastic resonance in shear-induced melting of sliding bilayers (2003)
Das, Moumita, Ananthakrishna, G, Ramaswamy, Sriram
The far-from-equilibrium dynamics of two crystalline two-dimensional monolayers driven past each other is studied using Brownian dynamics simulations. While at very high and low driving rates the...
Spatiotemporal rheochaos in nematic hydrodynamics (2003)
Chakrabarti, Buddhapriya, Das, Moumita, Dasgupta, Chandan, Ramaswamy, Sriram, Sood, A. K.
Motivated by the observation of rheochaos in sheared wormlike micelles [Bandyopadhyay et al., Phys. Rev. Lett, 84 2022, (2000); Europhys. Lett. 56, 447 (2001); Pramana 53, 223 (1999)] we study the...
Rheology of Active-Particle Suspensions (2003)
Hatwalne, Yashodhan, Ramaswamy, Sriram, Rao, Madan, Simha, R. Aditi
We study the interplay of activity, order and flow through a set of coarse-grained equations governing the hydrodynamic velocity, concentration and stress fields in a suspension of active,...
Collective stochastic resonance in shear-induced melting of sliding bilayers (2003)
Das, Moumita, Ananthakrishna, G., Ramaswamy, Sriram
The far-from-equilibrium dynamics of two crystalline two-dimensional monolayers driven past each other is studied using Brownian dynamics simulations. While at very high and low driving rates the...
Collective stochastic resonance in shear-induced melting of sliding bilayers (2003)
Das, Moumita, Ananthakrishna, G, Ramaswamy, Sriram
The far-from-equilibrium dynamics of two crystalline two-dimensional monolayers driven past each other is studied using Brownian dynamics simulations. While at very high and low driving rates the...
Anomalous Heat Conduction in One-Dimensional Momentum-Conserving Systems (2002)
Narayan, Onuttom, Ramaswamy, Sriram
We show that for one-dimensional fluids the thermal conductivity generically diverges with system size L as L1/3, as a result of momentum conservation. Our results are consistent with the...
Physica A30 (20"] 262 -- 269 (2002)
R. Aditi Simha, Sriram Ramaswamy, Centre For
General principles of symmetry and conservation are used to construct the hydrodynamic equations for orientationally ordered suspensions of self-propelled particles (SPPs). Without knowledge of the...
Active nematics on a substrate: giant number fluctuations and long-time tails (2002)
Ramaswamy, Sriram, Simha, R. Aditi, Toner, John
We construct the equations of motion for the coupled dynamics of order parameter and concentration for the nematic phase of driven particles on a solid surface, and show that they imply (i) giant...
Simha, Aditi R, Ramaswamy, Sriram
We construct the hydrodynamic equations for suspensions of self-propelled particles (SPPs) with spontaneous orientational order, and make a number of striking, testable predictions: (i) Nematic SPP...
A ratchet for heat transport between identical reservoirs (2002)
Das, Souvik, Narayan, Onuttom, Ramaswamy, Sriram
A one-dimensional periodic array of elastically colliding hard points, with a non-centrosymmetric unit cell, connected at its two ends to {\em identical but non-thermal} energy reservoirs, is shown...
Anomalous heat conduction in one dimensional momentum-conserving systems (2002)
Narayan, Onuttom, Ramaswamy, Sriram
We show that for one dimensional systems with momentum conservation, the thermal conductivity $\kappa$ generically diverges with system size as $L^{1/3}.$
Melting-freezing cycles in a relatively sheared pair of crystalline monolayers (2002)
Das, Moumita, Ramaswamy, Sriram, Ananthakrishna, G.
The nonequilibrium dynamical behaviour that arises when two ordered two-dimensional monolayers of particles are sheared over each other is studied in Brownian dynamics simulations. A curious sequence...
A ratchet for heat transport between identical reservoirs (2002)
Das, Souvik, Narayan, Onuttom, Ramaswamy, Sriram
A one-dimensional periodic array of elastically colliding hard points, with a non-centrosymmetric unit cell, connected at its two ends to {\em identical but non-thermal} energy reservoirs, is shown...
Simha, Aditi R, Ramaswamy, Sriram
We construct the hydrodynamic equations for suspensions of self-propelled particles (SPPs) with spontaneous orientational order, and make a number of striking, testable predictions: (i) Nematic SPP...
Anomalous Heat Conduction in One-Dimensional Momentum-Conserving Systems (2002)
Narayan, Onuttom, Ramaswamy, Sriram
We show that for one-dimensional fluids the thermal conductivity generically diverges with system size L as L1/3, as a result of momentum conservation. Our results are consistent with the...
A ratchet for heat transport between identical reservoirs (2002)
Das, Souvik, Narayan, Onuttom, Ramaswamy, Sriram
A one-dimensional periodic array of elastically colliding hard points, with a non-centrosymmetric unit cell, connected at its two ends to {\em identical but non-thermal} energy reservoirs, is shown...
Theory of suspension segregation in partially filled horizontal rotating cylinders (2001)
Govindarajan, Rama, Nott, Prabhu R, Ramaswamy, Sriram
It is shown that a suspension of particles in a partially-filled, horizontal, rotating cylinder is linearly unstable towards axial segregation and an undulation of the free surface at large enough...
Issues in the Statistical Mechanics of Steady Sedimentation (2001)
A critical review is presented of recent experimental and theoretical work on the steady sedimentation of particulate suspensions in viscous uids. The point of view is that of a practitioner of...
Theory of Suspension Segregation in Partially Filled Horizontal Rotating Cylinders (2001)
Govindarajan, Rama, Nott, Prabhu R., Ramaswamy, Sriram
It is shown that a suspension of particles in a partially-filled, horizontal, rotating cylinder is linearly unstable towards axial segregation and an undulation of the free surface at large enough...
Simha, R. Aditi, Ramaswamy, Sriram
We construct the hydrodynamic equations for {\em suspensions} of self-propelled particles (SPPs) with spontaneous orientational order, and make a number of striking, testable predictions:(i) SPP...
Das, Dibyendu, Basu, Abhik, Barma, Mustansir, Ramaswamy, Sriram
We study the coupled dynamics of the displacement fields in a one-dimensional coupled-field model for drifting crystals, first proposed by Lahiri and Ramaswamy [Phys. Rev. Lett. 79, 1150 (1997)]. We...
Driven Heisenberg Magnets: Nonequilibrium Criticality, Spatiotemporal Chaos and Control (2001)
Das, Jayajit, Rao, Madan, Ramaswamy, Sriram
We drive a $d$-dimensional Heisenberg magnet using an anisotropic current. The continuum Langevin equation is analysed using a dynamical renormalization group and numerical simulations. We discover a...
Phase Diagram of a Two-Species Lattice Model with a Linear Instability (2001)
Ramaswamy, Sriram, Barma, Mustansir, Das, Dibyendu, Basu, Abhik
We review recent progress in understanding the full phase diagram of a one-dimensional, driven, two-species lattice model [Lahiri and Ramaswamy, PRL 79 (1997) 1150] in which the mobility of each...
Das, Dibyendu, Basu, Abhik, Barma, Mustansir, Ramaswamy, Sriram
We study the coupled dynamics of the displacement fields in a one-dimensional coupled-field model for drifting crystals, first proposed by Lahiri and Ramaswamy [Phys. Rev. Lett. 79, 1150 (1997)]. We...
Das, Dibyendu, Basu, Abhik, Barma, Mustansir, Ramaswamy, Sriram
We study the coupled dynamics of the displacement fields in a one dimensional coupled-field model for drifting crystals, first proposed by R.Lahiri and S.Ramaswamy [{\em Phys. Rev. Lett.} {\bf 79},...
Hatwalne, Yashodhan, Ramaswamy, Sriram
We analyse the effect of thermal fluctuations on the elastic constants of the decoupled lamellar phase of tethered, crystalline membranes. Using a momentum-shell renormalization group technique, we...
Nonequilibrium Fluctuations, Traveling Waves, and Instabilities in Active Membranes (2000)
Ramaswamy, Sriram, Toner, John, Prost, Jacques
The stability of a flexible fluid membrane containing a distribution of mobile, active proteins (e.g., proton pumps) is shown to depend on the structure and functional asymmetry of the proteins. A...
Inequivalence of dynamical ensembles in a generalized driven diffusive lattice gas (2000)
Acharyya, Muktish, Basu, Abhik, Pandit, Rahul, Ramaswamy, Sriram
We generalize the driven diffusive lattice gas model by using a combination of Kawasaki and Glauber dynamics. We find via Monte Carlo simulations and perturbation studies that the simplest possible...
Strong phase separation in a model of sedimenting lattices (2000)
Lahiri, Rangan, Barma, Mustansir, Ramaswamy, Sriram
We study the steady state resulting from instabilities in crystals driven through a dissipative medium, for instance, a colloidal crystal which is steadily sedimenting through a viscous fluid. The...
Inequivalence of dynamical ensembles in a generalized driven diffusive lattice gas (2000)
Acharyya, Muktish, Basu, Abhik, Pandit, Rahul, Ramaswamy, Sriram
We generalize the driven diffusive lattice gas model by using a combination of Kawasaki and Glauber dynamics. We find via Monte Carlo simulations and perturbation studies that the simplest possible...
Nonequilibrium Fluctuations, Traveling Waves, and Instabilities in Active Membranes (2000)
Ramaswamy, Sriram, Toner, John, Prost, Jacques
The stability of a flexible fluid membrane containing a distribution of mobile, active proteins (e.g., proton pumps) is shown to depend on the structure and functional asymmetry of the proteins. A...
Inequivalence of Dynamical Ensembles in a Generalised Driven Diffusive Lattice Gas (1999)
Acharyya, Muktish, Basu, Abhik, Pandit, Rahul, Ramaswamy, Sriram
We generalise the Driven Diffusive Lattice Gas (DDLG) model by using a combination of Kawasaki and Glauber dynamics. We find via Monte Carlo simulations and perturbation studies that the simplest...
Nonequilibrium Fluctuations, Travelling Waves, and Instabilities in Active Membranes (1999)
Ramaswamy, Sriram, Toner, John, Prost, Jacques
The stability of a flexible fluid membrane containing a distribution of mobile, active proteins (e.g. proton pumps) is shown to depend on the structure and functional asymmetry of the proteins. A...
Suspensions far from equilibrium (1999)
A review is presented of recent experimental and theoretical work on the dynamics of suspensions of particles in viscous fluids, with emphasis on phenomena that should be of interest to experimenters...
Strong Phase Separation in a Model of Sedimenting Lattices (1999)
Lahiri, Rangan, Barma, Mustansir, Ramaswamy, Sriram
We study the steady state resulting from instabilities in crystals driven through a dissipative medium, for instance, a colloidal crystal which is steadily sedimenting through a viscous fluid. The...
Nonequilibrium noise and instabilities in membranes with active pumps (1999)
Ramaswamy, Sriram, Toner, John, Prost, Jacques
We study the statistical properties and dynamics of flexible fluid membranes containing active transmembrane proteins and find that such active membranes can be either stable or unstable to small...
Basappa, Geetha, Kumaran, V., Nott, Prabhu R., Ramaswamy, Sriram, Naik, V. M., ...
We present important new results from light-microscopy and rheometry on a moderately concentrated lyotropic smectic, with and without particulate additives. Shear-treatment aligns the phase rapidly,...
Travelling waves in a drifting flux lattice (1999)
Simha, R. Aditi, Ramaswamy, Sriram
Starting from the time-dependent Ginzburg-Landau (TDGL) equations for a type II superconductor, we derive the equations of motion for the displacement field of a moving vortex lattice without inertia...
Nonequilibrium noise and instabilities in membranes with active pumps (1999)
Ramaswamy, Sriram, Toner, John, Prost, Jacques
We study the statistical properties and dynamics of flexible fluid membranes containing active transmembrane proteins and find that such active membranes can be either stable or unstable to small...
Suspensions far from equilibrium (1999)
A review is presented of recent experimental and theoretical work on the dynamics of suspensions of particles in viscous fluids, with emphasis on phenomena that should be of interest to experimenters...
Correlations and Freezing in Steadily Settling Suspensions (1998)
Lahiri, Rangan, Ramaswamy, Sriram
We study the liquid-solid transition in a collection of interacting particles moving through a dissipative medium under the action of a constant, spatially uniform external force, e.g. a...
Basu, Abhik, Bhattacharjee, Jayanta K, Ramaswamy, Sriram
We show that a recently proposed [J. Fleischer and P.H. Diamond, {\em Phys. Rev. E}{\bf 58}, R2709 (1998)] one-dimensional Burgers-like model for magnetohydrodynamics (MHD) is in effect identical to...
Hydrodynamic Screening And Nonequilibrium Phase Transitions In Stokesian Fluidised Beds (1998)
Alex J Levine, Sriram Ramaswamy, Erwin Frey
this paper we calculate the statistical properties of velocity and concentration fluctuations in steady-state sedimentation ignoring fluid inertia, using the method
Hydrodynamic Screening And Nonequilibrium Phase Transitions In Stokesian Fluidised Beds (1998)
Alex J Levine, Sriram Ramaswamy, Erwin Frey
this paper we calculate the statistical properties of velocity and concentration fluctuations in steady-state sedimentation ignoring fluid inertia, using the method
Screened and Unscreened Phases in Sedimenting Suspensions (1998)
Levine, Alex, Ramaswamy, Sriram, Frey, Erwin, Bruinsma, Robijn
A coarse-grained stochastic hydrodynamical description of velocity and concentration fluctuations in steadily sedimenting suspensions is constructed, and analyzed using self-consistent and...
Are Steadily Moving Crystals Unstable? (1997)
Lahiri, Rangan, Ramaswamy, Sriram
We study the dynamics of small fluctuations about the uniform state of a crystal m