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Pramoda Kumar

Ph.D. Coordinator of Physics, Assistant Professor of Physics, Ashoka University

Ph.D. Centre for Liquid Crystal Research (renamed as Centre for Nano and Soft Matter Sciences), Bangalore

Research Experience:

  • The Jacob Blaustein Institutes for Desert Research – Ben Gurion University of the Negev, Israel (Blaustein Postdoctoral Fellow Nov. 2015 – Feb. 2019)

  •  Centre for Nano and Soft Matter Sciences, Bangalore (Visiting Scientist, May 2015 – Sept. 2015)

  • Harvard-School of Engineering and Applied Sciences, Cambridge (Postdoctoral fellow, Sept. 2013 – Feb, 2015).

  • Weizmann Institute of Science, Israel ( Feinberg Graduate School Postdoctoral Fellow, Dec. 2012– Aug. 2013)

  • Max-Plank Institute for Dynamics and Self-Organization, Goettingen (Postdoctoral Fellow, Sept. 2010 – Oct.2012)

Research Interest:

Experimental soft-condensed matter physics, pattern formation in dissipative systems, interface instability, charge transport phenomena in ion-selective membranes, bio-physics and non-Newtonian hydrodynamics

The life around us and most of the items that we use in our day-to-day life are made up of partially ordered, self-organizing and self-assembling materials such as gels, foams, polymers, liquid crystals, colloids, complex fluids and granular materials; these are collectively referred to as ‘Soft Matter’. Soft matter’s responses to the external perturbations like mechanical, electrical, thermal and optical stresses are usually non-linear in nature and hard to predict from the behavior of its basic units; these basic units are usually orders of magnitude bigger than the size of an atom, and yet are insignificantly small compared to the macroscopic size of the sample. Short-range intermolecular interactions, dissipation, disorder, thermal fluctuations, entropy and brownian motions are dominant factors in these systems.

Often, these materials can be used as model systems to understand the structure and function of complex biological units; for example, lipid bilayers formed by surfactant-water system could be used to gain the basic understanding of the working mechanism of biological membranes; similarly, myelin structure formation at the interface of liquid crystals-aqueous surfactant solutions could be a model system to study the myelin sheath around the axon of a neuron. The flow dynamics of non-Newtonian fluids could be the model system to understand the flow behavior of glacier ice.

The soft-condensed matter research, in general, is highly interdisciplinary in nature , and usually covers both basic and applied facets of soft matter sciences. Broadly, our research work  focuses on experimental investigation of electric, magnetic and flow fields induced instabilities in soft matter/complex fluids using different types of electro-optical techniques. Different types of optical microscopy, microfluidics, advanced imaging and image analysis are the techniques employed throughout our research activity.

Some research projects that we are planning to explore in our lab are

    .    Charge/mass transport phenomena in ion-selective membranes/ porous medium and associated hydrodynamic instabilities.

    .    Dynamics of Lubricated Non-Newtonian fluids as model systems to understand the flow of glacier ice.

    .    Electro-convection in anisotropic systems such as liquid crystals, leaky dielectric fluids such as oil, strong electrolyte solutions and multi-phase systems in order to gain universal understanding of the phenomena.

    .    Biophysics – Hydrodynamics of vertical migration of dinoflagellates (in collaboration with Dr. Sougata Roy of biology department of Ashoka University)

Peer-reviewed journals:

  • Pramoda Kumar, S. Zuri, D. Kogan, M. Gottlieb and R. Sayag (2021) Lubricated gravity currents of power-law fluids, J. Fluid Mech.,916, A33.
  • Pramoda Kumar, S.M. Rubinstein, I. Rubinstein and B. Zalzman (2020), Mechanisms of hydrodynamic instability in concentration polarization, Phys. Rev. Res., 2, 033365.
  • K. S. Krishnamurthy, Pramoda Kumar, N. B. Palakurthy, C.V. Yelamaggad, and E. G. Virga (2016): Interfacial and morphological features of a twist-bend nematic drop, Soft Matter 12, 4967
  • KS Krishnamurthy and Pramoda Kumar (2016): Effect of waveform of the driving field on electroconvection near the dielectric inversion frequency, Phys. Rev. E. 93, 022706.
  • Karthik Peddireddy, Pramoda Kumar, Shashi Thutupalli, Stephan Herminghaus and Christian Bahr (2013): Myelin structures formed by thermotropic smectic liquid crystals, , Langmuir 29, 15682
  • KS Krishnamurthy, Pramoda Kumar (2013): Inhomogeneous Freedericksz effect in a quarter turn twisted achiral smectic C liquid crystal, , EPL (Europhysics Letters) 102, 66001
  • K. S. Krishnamurthy, Pramoda Kumar and Vijay Kumar (2013): Polarity-sensitive transient patterned state in a twisted nematic liquid crystal driven by very low frequency field, Phys. Rev. E. 87, 022504.
  • Karthik Peddireddy, Pramoda Kumar, Shashi Thutupalli, Stephan Herminghaus and Christian Bahr (2012): Solubilization of thermotropic liquid crystal compounds in aqueous surfactant solutions, Langmuir 28, 12426.
  • Pramoda Kumar, Jana Heuer, T. Toth-Katona, N. Eber, and A. Buka (2010): Convection-roll instability in spite of large stabilizing torque, Phys. Rev. E. 81, 020702(R).
  • Pramoda Kumar, Y. Marinov, H. P. Hinov, Uma S. Hiremath, C. V. Yelamaggad, K. S. Krishnamurthy, and A. G. Petrov (2009): Converse Flexoelectric Effect in Bent-Core Nematic Liquid Crystals, J. Phys. Chem. B 113, 9168.
  • Pramoda Kumar, Uma S .Hiremath, C. V. Yelamaggad,  Alex G. Rossberg and K. S. Krishnamurthy (2008): Electroconvection in a homeotropic bent-rod nematic liquid crystal beyond the dielectric inversion frequency, J. Phys. Chem. B 112, 9753.
  • Pramoda Kumar, Uma S .Hiremath, C. V. Yelamaggad,  Alex G. Rossberg and K. S. Krishnamurthy (2008): Drifting periodic structures in a degenerate-planar bent-rod nematic liquid crystal beyond the dielectric inversion frequency, J. Phys. Chem. B (Lett) 112, 9270.
  • K. S. Krishnamurthy and Pramoda Kumar (2007): Emergence of periodic order in electric field driven planar nematics: an exclusive ac effect absent in static fields, Phys. Rev. E. 76, 051705.
  • Pramoda Kumar, S. N. Patil, U. S. Hiremath, and K. S. Krishnamurthy (2007): Instabilities across the isotropic conductivity point in a nematic phenyl benzoate under ac driving. J. Phys. Chem. B, 111, 8792.
  • K. S. Krishnamurthy and Pramoda Kumar( 2007), Drifting undulations in an achiral Smectic C liquid crystal driven by a static electric field, J. Phys. Chem. B (Lett) 111, 2423.
  • Pramoda Kumar and K. S. Krishnamurthy (2007): Gradient flexoelectric switching response in a nematic phenyl benzoate, Liq. Cryst. 34, 257.
  • Pramoda Kumar and K. S. Krishnamurthy (2006) Competing modes of instability in an electrically driven nematic with a small positive dielectric anisotropy, Phys. Rev. E. 74, 031705.
  • Pramoda Kumar and K. S. Krishnamurthy (2006): Flexoelectric response at defect sites in nematic inversion walls, Liq. Cryst., 33, 131.

Review

  • Flexoelectrically driven instabilities in liquid crystals, K. S. Krishnamurthy, Pramoda Kumar and Pramod Tadapatri , Journal of the Indian Institute of Science 89:2 Apr–Jun 2009
Study at Ashoka

Study at Ashoka