Prabhakar Ranganathan B.Tech.(Chem Eng), Indian Institute of Technology, Madras, 1993 M.S.(Chem Eng), Indian Institute of Technology, Madras, 1998 PhD (Chem Eng), Monash University, 2007 Lecturer email: prabhakar.ranganathan@eng.monash.edu.au tel:    +61 3 9905 3480 fax:   +61 3 9905 1825 Room 123, Building 31, Clayton Campus

Professional Appointments

• 2007-present: Lecturer, Department of Mechanical Engineering, Monash University
• 2005-2007: Post-doctoral Fellow, Research School of Chemistry, Australian National University

Professional Affiliations 

• Member, Australian Society of Rheology
• Member, Society of Rheology

Current Research

Areas of interest

Coarse-graining of long range interactions between particles in a suspension:

Particles in a suspension can interact with each other even if they are widely separated. For example, the motion of any one particle disturbs the solvent around it and therefore affects the motion of its neighbours. Electrostatic interactions between charged particles is another important example. Simulations of such interactions typically are computationally demanding because of their long spatial range. I am interested in developing methods for "coarse-graining", that is, replacing particle-particle interactions with particle-cluster interactions, to speed up simulations. Coarse-grained models can be used to understand the behaviour of complex fluids such as polymer solutions, or polymer-particle suspensions, in complex flows.

Elastohydrodynamics of driven semiflexible filaments:

The coupling between hydrodynamics and elasticity has very interesting implications for the motion of microscopic semiflexible filaments that are driven by external or internal agents. Flagellar propulsion in bacteria and other motile microbes are beautiful examples of elastohydrodynamic coupling, and understanding this coupling is the key to designing efficient propulsion and navigation systems for self-propelled microscopic swimming robots. I am looking for a PhD student in this area (for details, see pdf).

Hydrodynamics of biomembranes:

It is becoming increasingly apparent that lipid bilayer membranes are as important as genes and proteins in the functioning of a biological cell. I am interested in studying how "dead" colloidal particles such as viruses, or aggregates such as polymers, recognize targets sites on the surfaces of membranes.  In particular, I would like to explore the role of fluid flow in the behaviour of microscopic particles and polymers near thermally fluctuating membranes (or even liquid-liquid interfaces). I have currently PhD positions available on two different problems in this area (for details, see pdf1 and pdf2).

Collective motion of motile bacteria:

When a bunch of self-propelled bacteria get together, either in a suspension, or on a surface, they really have a party! Their collective motion is dominated by large scale patterns such as eddies and jets, and remind one of the patterns observed in large flocks of birds, or shoals of fish. I am interested in  a) understanding how these macroscopic patterns are correlated with propulsion at the level of an individual bacterium, and b) the implications of such collective motion to things like the rheology of the bacterial suspension, or the colonization of surfaces. I am looking for two PhD students in this area (pdf's coming soon!).

Complex flows of dilute polymer solutions:

Small amounts of polymeric additives can dramatically alter the dynamic properties of otherwise Newtonian liquids in flow. This has in fact been used in the industry in a range of applications such as ink-jet printing, agricultural spraying, turbulent-drag reduction etc. While it is known that the ability of polymer molecules to stretch out in regions where the flow has strong a extensional component has something to do with all of this, we do not have a detailed predictive understanding. One of the problems is that conventional Computational Fluid Dynamics (CFD) methods often struggle to handle polymer solutions. I am interested in developing new efficient numerical methods for simulations of polymer solutions in complex flow situations, and a PhD position available in this area (see pdf).

Selected Publications

• E.M. Sevick, R. Prabhakar, S.R. Williams, and D.J. Searles (2008) "Fluctuation Theorems", Ann. Rev. Phys. Chem., 59, 603-633.
• R. Prabhakar, E. M. Sevick, and D. R. M. Williams (2007), "Coarse-graining intramolecular hydrodynamic interaction in dilute solutions of flexible polymers", Phys. Rev. E, 76, 011809.

• T. Sridhar, D. A. Nguyen, R. Prabhakar, and J. R. Prakash (2007), "Rheological observation of the glassy dynamics of dilute polymer solutions near the coil-stretch transition in elongational flows", Phys. Rev. Lett., 98, 167801.

• R. Prabhakar, J. R. Prakash, and T. Sridhar (2006), "Effect of configuration-dependent intramolecular hydrodynamic interaction on elasto-capillary thinning and break-up of filaments of dilute polymer solutions", J. Rheol., 50, 925-947.

• R. Prabhakar and J. R. Prakash (2006), "Gaussian approximation for finitely extensible bead-spring chains with hydrodynamic interaction", J. Rheol., 50, 561-593.

• R. Prabhakar, J. R. Prakash, and T. Sridhar (2004), "A successive fine-graining scheme for predicting the rheological properties of dilute polymer solutions", J. Rheol., 48, 1251–1278.

• R. Prabhakar and J. R. Prakash (2004), "Multiplicative separation of the influences of excluded volume, hydrodynamic interactions and finite extensibility on the rheological properties of dilute polymer solutions", J. Non-Newtonian Fluid Mech., 116, pp. 163–182.

• Ravi Prakash Jagadeeshan, Reader, Chemical Engineering, Monash University

• Tam Sridhar, Professor, Chemical Engineering, Monash University

• Edith Sevick, Leader, Polymers and Soft Condensed Matter Group, Research School of Chemistry, Australian National University

• David Williams, Professor, Applied Mathematics Department, Research School of Physical Sciences and Engineering, Australian National University

• Summer Research Experience-2007-08
• Final Year Projects-2008