Rochish Madhukar Thaokar
123, Chemical Engineering
Gold Medal BTech Nagpur University 1995.
Kuloor Memorial Award Best ME Student IISc Bangalore 1997.
A conducting drop suspended in a viscous dielectric and subjected toa uniform DC electric field deforms to a steady-state shape when the electric stress and the capillary stress balance. Beyond a critical electric capillary number Ca, which is the ratio of the electric to the capillary stress, a drop undergoes breakup. Although the steady-state deformation is independent of the viscosity ratio λ of the drop and the medium phase, the breakup itself is dependent upon λ and Ca. We perform a detailed experimental and numerical analysis of the axisymmetric shape prior to breakup (ASPB), which explains that there are three different kinds of ASPB modes: the formation of lobes, pointed ends and nonpointed ends. The axisymmetric shapes undergo transformation into the non-axisymmetric shape at breakup (NASB) before disintegrating which are modes of charged lobes disintegration, regular jets (which can undergo a whipping instability) and open jets, respectively. We understand drop electrohydrodynamics using experiments, theory and Boundary element calculations.
We are interested in understanding the physics of effect of electric field on vesicles. Cylindrical experiments are a good prototype for the same. Experiments show that a cylindrical vesicle when subjected to an axial electric field, displays an axisymmetric pearling instability (the Rayleigh–Plateau instability) beyond a threshold electric field. The tension required to induce the instability is produced by the electric field. At higher values of field strength however, a stabilizing action of the electric field is seen. This renders the fastest growing wave number, km, independent of the electric field at high electric field strength. At long times, a pearled state is observed, with the pearls separated by short cylindrical nanotubules. The focus in the group is now on understanding electroporation with applications in biomedical industry.
We are interested in understanding the physics of elastic capsules using electric fields. Our study indicates a new method of determining Young’s modulus, Bending modulus and thickness of the membrane using electric fields. We also have a novel method of producing nonspherical capsules. We have demonstrated that electrohydrodynamics can be used to understand the mechanism of capsule formation. The aim in this study is to use electrohydrodynamics in appications of capsules in FMCG and Biomedical industry.