RESEARCH


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I am working in the field of microfluidics, protein crystallization and droplet hydrodynamics. Brief description about my research activity is mentioned here.
Hydrodynamics of interacting droplets
Presence of a neighboring droplet affects the flow pattern inside an evaporating droplet though they do not have any physical contact between them. The symmetric flow pattern inside a single droplet becomes asymmetric in the presence of the neighboring droplet. The neighboring droplet can also drive the droplet. The flow pattern inside evaporating droplets in the presence of neighboring droplet has been studied both experimentally and numerically. The works have been published in the following papers.
Multimedia Video : Two Droplets      APS Gallery of Fluid Motion
1. Tapan K Pradhan and Pradipta K Panigrahi, Internal convection of two interacting liquid slugs of aqueous solution placed inside a microchannel, 69th Annual Meeting of the APS Division of Fluid Dynamics, December 20-22, Portland, USA (2016) DOI : meetings.aps.org/Meeting/DFD16/Session/A25.8
2. Tapan K Pradhan and Pradipta K Panigrahi, Influence of an adjacent droplet on fluid convection inside an evaporating droplet of binary mixture, Colloids and Surfaces A, 500, 2016 DOI : 10.1016/j.colsurfa.2016.03.073
3. Tapan K Pradhan and Pradipta K Panigrahi, Deposition pattern of interacting droplets, Colloids and Surfaces A, 482, 2015 DOI : 10.1016/j.colsurfa.2015.07.013

Internal convection of evaporating droplets
Evaporating droplet has many practical application like protein crystallization, deposition pattern, disease diagnosis etc. Evaporation from the droplet surface induces flow inside the droplet. The flow may cause due to surface tension driven Marangoni convection or Buyancy driven Rayleigh convection. The flow inside a droplet of aqueous solution is caused by Rayleigh convection. The results of our work have been presented in the following papers.
Multimedia Video : Evaporative Droplet
1. Tapan K Pradhan and Pradipta K Panigrahi, Evaporation-induced natural convection of a liquid slug of binary mixture inside a microchannel: effect of confinement, Microfluidics and Nanofluidics, 20, 2016 DOI : 10.1007/s10404-016-1782-6
2. T. K. Pradhan and P. K. Panigrahi, Experimental investigation of fluid convection inside an evapoating droplet of binary mixture, 42nd National conference on Fluid Mechanics and Fluid Power, December 14-16, NIT Karnataka, Surathkal, India (2015).
3. Natural convection inside an evaporating liquid bridge of binary mixture, 3rd National and 1st International ISHMT-ASTFE Heat and Mass Transfer Conference, December 17-20, ISRO, Trivandrum, India (2015).

Fluid dynamics of protein crystallization process
Hydrodynamics during protein crystallization plays a significant role in crystallization process and crystal quality. Protein crystallization process causes flow arround the crystalls due to buoyancy force. In vapor diffusion method of protein crystallization, flow is induced inside the droplet due to evaporation from the droplet surface. We have studied the internal convection inside droplet during sitting drop method of protein crystallization.
Multimedia Video : Protein Crystallization
1. T. Pradhan, M. Asfer and P. K. Panigrahi, Droplet hydrodynamics during lysozyme protein crystallization, Physical Review E 86, 2012 DOI : 10.1103/PhysRevE.86.051602

Deposition pattern of drying droplets
An evaporating droplet containing suspended particles leaves a deposition pattern on the substrate surface after drying. The deposition pattern strongly depends on the internal convection of the droplet. Evaporation driven pattern deposition has many practical implications like two-dimensional crystallization, surface coating, DNA chip manufacturing, biosensing of protein, disease diagnosis etc. Our study related to deposition pattern has been presented in the following published papers.
Multimedia Video : Drying Droplet
1. Tapan K Pradhan and Pradipta K Panigrahi, Deposition pattern of interacting droplets, Colloids and Surfaces A, 482, 2015 DOI : 10.1016/j.colsurfa.2015.07.013
2. Tapan K Pradhan and Pradipta K Panigrahi, Convection Inside a Pinned Water Droplet During Drying Process, Proceeding of the 5th International and 41st National conference on Fluid Mechanics and Fluid Power, December 12-14, IIT Kanpur, Kanpur, India (2014). DOI : 10.1007/978-81-322-2743-4_126

Droplet actuation in digital microfluidics
Droplet actuation playes significant role in digital microfluidics. The manupulation of droplet in droplet based microfluidics is done by different methods like thermal gradient, electro-wetting etc. Here, we have studied the internal flow pattern of a water droplet placed on a temperature gradient surface. Micro-PIV, confocal microscope and IR thermography have been used here to study the phenomena. The work has been presented in the following published article.
Multimedia Video : Thermocapillary Convection
1. Tapan K Pradhan and Pradipta K Panigrahi, Thermo-capillary convection inside a stationary sessile water droplet on a horizontal surface with an imposed temperature gradient, Experiments in Fluids 56, 2015 DOI : 10.1007/s00348-015-2051-2