## Scientific Contributions

Professor Gautam Biswas has carried out detailed analytical and numerical studies of long lasting values in many areas. The foci of his research have been on the analysis of physical mechanisms and furtherance of understanding. The areas of particular interest to Professor Biswas have been:

#### 1. Prediction of Bubble Growth in Boiling

Some of the recent contributions involve prediction of bubble growth in film boiling. Professor Biswas with his colleagues, has developed a computational tool that has enabled them to explore a very important area of Engineering Science. The effort has resulted in several publications in top-tier journals. Professor Biswas has performed simulations of film boiling and bubble formation in water and R134a using a Coupled Level-Set and Volume-of-Fluid (CLSVOF) based interface tracking method. The algorithm has been extended to simulate boiling in presence of Electrohydrodynamic forces.** The most significant contribution of the group is the following**. With the growth of the film the influence of heat flux decreases and the Rayleigh-Taylor mode of instability sets in with the surface tension force competing with the destabilizing gravitational force. The instability mechanisms responsible for bubble growth, change from Rayleigh-Taylor to Taylor-Helmholtz as the wall superheat is increased. The following paper has been highly admired by peers in the field:

G. Tomar, G. Biswas, A. Sharma and S.W.J. Welch, Multi-mode Analysis of Bubble Growth in Saturated Film Boiling, **Physics of Fluids**, Vol. 20, 092101-1 – 092101-7, (2008).

The other notable publications in related areas are:

V. Pandey, G. Biswas, and A. Dalal, Effect of superheat and electric field on saturated film boiling, ** Physics of Fluids**, Vol. 28, 052102-1- 052102-18, (2016)

A. Hens, G. Biswas and S. De, Evaporation of water droplets on Pt-surface in presence of external electric field – A molecular dynamics study, ** The Journal of Chemical Physics**, Vol. 143, 094702-1 – 094702-11, (2015)

A. Hens, G. Biswas and S. De, Analysis of interfacial instability and multimode bubble formation in saturated pool boiling using Coupled Level Set and Volume- of- Fluid approach, ** Physics of Fluids**, Vol. 26, pp. 012105-1 – 012105-14, (2014)

A. Hens, R. Agarwal and G. Biswas, Nanoscale study of boiling and evaporation in a liquid Ar film on a Pt heater using molecular dynamics simulation, ** International Journal of Heat and Mass Transfer**, Vol. 71, pp. 303-312 (2014)

G. Tomar, G. Biswas, A. Sharma and S.W.J. Welch, Influence of Electric Field on Saturated Film Boiling, ** Physics of Fluids**, Vol. 21, 032107-1 – 032107-8 (2009).

G. Tomar, D. Gerlach, G. Biswas, N. Alleborn, A. Sharma, F. Durst S. W. J. Welch, and A. Delgado, Two-phase Electrohydrodynamic Simulations Using a Volume-of-Fluid Approach, ** Journal of Computational Physics**, Vol. 227, pp 1267-1285, (2007).

S.W.J. Welch and G. Biswas, Direct Simulation of Film Boiling Including Electrohydrodynamic Forces, ** Physics of Fluids**, Vol. 19, 012106-1 – 012106-11, (2007).

G. Tomar, G. Biswas, A. Sharma and A. Agrawal, Numerical Simulation of Bubble Growth in Film Boiling Using CLSVOF Method, ** Physics of Fluids**, Vol. 17, 112103-1 – 112103-13, (2005).

D. Agarwal, S.W.J. Welch, G. Biswas, and F. Durst, Planar Simulation of Bubble Growth in Film Boiling in Near-Critical Water Using a Variant of the VOF Method, ** Journal of Heat Transfer (ASME)**, Vol. 126, pp. 329-338, (2004).

#### 2. Dynamics of Falling Drops on a Liquid Surface

The study deals with the understanding of drop dynamics during partial coalescence. When a drop of liquid-1 falls through liquid-2 to eventually hit the liquid-2—liquid-1 interface, its initial impact on the interface can produce daughter droplets of liquid-1. In some cases, a partial coalescence cascade governed by self-similar capillary-inertial dynamics is observed, where the fall of the secondary droplets in turn continues to produce further daughter droplets. A transition regime from partial to complete coalescence proceeds via a number of intermediate steps, such as thick and thin jet formation and gas-bubble entrapment. The following publications have long lasting value:

B. Ray, G. Biswas and A. Sharma, Regimes during liquid drop impact on a liquid pool, ** Journal of Fluid Mechanics**, Vol. 768, pp. 492-523, (2015).

B. Ray, G. Biswas and A. Sharma, Bubble pinch-off and scaling during liquid drop impact on liquid pool, ** Physics of Fluids**, Vol. 24, pp. 082108-1 – 082108-11, (2012)

B. Ray, G. Biswas and A. Sharma, Generation of secondary droplets in coalescence of a drop at a liquid/ liquid interface, ** Journal of Fluid Mechanics**, Vol. 655, pp. 72-104, (2010)

#### 3. Enhancement of Heat Transfer in Heat Exchangers

Professor Gautam Biswas has conducted a wide range of numerical studies for the improvement of Heat Transfer in Fin-tube and Plate-fin heat Exchangers. The investigations address the fundamental mechanisms of heat transfer enhancement and suggest improvements in the practical applications. He was one of the members of a tripartite international project (INEEL-Idaho, IIT Kanpur and Yokohama National University) for the investigation of heat transfer enhancement of air-cooled condensers for geothermal power plants. The project was sponsored by NEDO, Japan. His work on enhancement of heat transfer has become textbook material [page 210-212, ** Principles of Convective Heat Transfer** by M. Kaviany, Springer, 2001]. He was one of the keynote speakers at the Twelfth International Heat Transfer Conference (IHTC), held in Grenoble, France. The publications endorsing this seminal contribution are:

G. Biswas and H. Chattopadhyay, Heat Transfer in a Channel Flow with Built-in Wing-Type Vortex Generators, ** International Journal of Heat and Mass Transfer**, vol. 35, pp. 803-814, (1992).

G. Biswas, P. Deb and S. Biswas, Generation of Longitudinal Streamwise Vortices - A Device for Improving Heat Exchanger Design, ** Journal of Heat Transfer (ASME)**, vol. 116, pp. 588-597, (1994).

G. Biswas, N.K. Mitra and M. Fiebig, Heat Transfer Enhancement in Fin-Tube Heat Exchangers by Winglet Type Vortex Generators, ** International Journal of Heat and Mass Transfer**, vol.37, pp. 283-291, (1994).

P. Deb, G. Biswas and N.K. Mitra, Heat Transfer and Flow Structure in Laminar and Turbulent Flows in a Rectangular Channel with Longitudinal Vortices, ** International Journal of Heat and Mass Transfer**, vol. 38, pp. 2427-2444, (1995).

G. Biswas, K. Torii, D. Fujii and K. Nishino, Numerical and Experimental Determination of Flow Structure and Heat Transfer Effects of Longitudinal Vortices in a Channel Flow, ** International Journal of Heat and Mass Transfer**, vol. 39, pp. 3441-3451, (1996).

A.A. Bastani Jahromi, N.K. Mitra and G. Biswas, Numerical Investigations on Enhancement of Heat Transfer in a Compact Fin-and-Tube Heat Exchanger Using Delta Winglet Type Vortex Generators, ** Enhanced Heat Transfer**, Vol.6, pp. 1-11, (1999).

R. Vasudevan, V. Eswaran, and G. Biswas, Winglet Type Vortex Generators for Plate-Fin Heat Exchangers Using Triangular Fins, ** Numerical Heat Transfer**, Part A, Vol. 38, pp. 533-555, (2000).

A. Jain, G. Biswas and D. Maurya, Winglet-Type Vortex Generators with Common-Flow-Up Configuration for Fin-Tube Heat Exchangers, ** Numerical Heat Transfer**, Part A, Vol. 43, pp. 201-219, (2003).

V. Prabhakar, G. Biswas and V. Eswaran, Numerical Prediction of Heat Transfer in a Channel with a Built-in Oval Tube and Various Arrangements of the Vortex Generators, ** Numerical Heat Transfer**, Part A, Vol. 44, pp. 315-333, (2003).

S. Tiwari, D. Maurya, G. Biswas and V. Eswaran, Heat Transfer Enhancement in Crossflow Heat Exchangers using Oval Tubes and Multiple Delta Winglets, ** International Journal of Heat and Mass Transfer**, Vol. 46, pp. 2841-2856, (2003).

S. Tiwari, G. Biswas, P.L.N. Prasad and S. Basu, Numerical Prediction of Flow and Heat transfer in a Rectangular Channel with a Built-in Circular Tube, ** Journal of Heat Transfer (ASME)**, Vol. 125, pp. 413-421, (2003).

S.R. Hiravennavar, E.G. Tulapurkara, G. Biswas, A Note on the Flow and Heat Transfer Enhancement in a Channel with Built-in Winglet Pair, ** Int. J. Heat and Fluid Flow** , Vol. 28, pp. 299–305, (2007).

G. Biswas, H. Chattopadhyay and A. Sinha, Augmentation of Heat Transfer by Creation of Streamwise Longitudinal Vortices using Vortex Generators, ** Heat Transfer Engineering**, Vol. 33, pp. 406 – 424, (2012).

A Pal, D. Bandyopadhyay, G. Biswas and V. Eswaran, Enhancement of Heat Transfer Using Delta-Winglet Type Vortex Generators with a Common Flow Up Arrangement, ** Numerical Heat Transfer** Part A, Vol. 61, pp. 912-928, (2012).

A. Sinha, K. A. Raman, H. Chattopadhyay and G. Biswas, Effects of different orientations of winglet arrays on the performance of plate-fin heat exchangers, ** International Journal of Heat and Mass Transfer**, Vol. 57, pp. 202–214, (2013).

P. Saha, G. Biswas and S. Sarkar, Comparison of winglet-type vortex generators periodically deployed in a plate-fin heat exchanger – A synergy based analysis, ** International Journal of Heat and Mass Transfer**, Vol. 74, pp. 292-305, (2014)

#### 4. Dynamics of Rising Air Bubbles through a Liquid Column

The problem of dynamic bubble formation from a submerged orifice in an immiscible Newtonian liquid has been addressed by Professor Biswas and his team. They have considered various cases for the surrounding liquid, namely the liquid in a quiescent condition and the liquid as a co-flowing stream with the gas. The full cycle, from formation to detachment of the bubbles and the corresponding bubble dynamics, was analyzed. The simulation results showed that the minimum radius of the neck decreases with a power law behavior and the power law exponent in a co-flowing liquid is less than 1/2 as predicted by the Rayleigh–Plesset theory for quiescent inviscid liquids. Single periodic and double periodic bubbling (with pairing and coalescence) regimes were observed in the investigations. Some often referred publications are:

I. Chakraborty, B. Ray, G. Biswas, F. Durst, A. Sharma, and P. S. Ghoshdastidar, Computational Investigation on Bubble Detachment from Submerged Orifice in Quiescent Liquid under Normal and Reduced Gravity, ** Physics of Fluids**, Vol. 21, pp. 062103-1 – 062103-17, (2009)

I. Chakraborty, G. Biswas, and P. S. Ghoshdastidar, Bubble generation in quiescent and co-flowing liquids, ** International Journal of Heat and Mass Transfer** , Vol. 54, pp. 4673 – 4688, (2011).

I. Chakraborty, G. Biswas and P.S. Ghoshdastidar, A coupled level-set and volume-of-fluid method for the buoyant rise of gas bubbles in liquids, ** International Journal of Heat and Mass Transfer**, Vol. 58, pp. 240–259, (2013).

I. Chakraborty, G. Biswas, S. Polepalle and P.S. Ghoshdastidar, Bubble Formation and Dynamics in a Quiescent High-Density Liquid, ** AIChE Journal**, Vol. 61, pp. 3996 - 4012, (2015).

#### 5. Bluff Body Flows

Interesting investigations in the wake zone of the bluff bodies placed in a uniform/ non-uniform stream have been conducted by Professor Biswas and co-researchers. Professor Biswas and co-researchers have focused on the spatial and temporal transitions of the wake. The transition sequence and the flow structures have been analyzed and significant new observations have been highlighted. These have been presented in several publications as cited below.

G. Biswas, H. Laschefski, N.K. Mitra and M. Fiebig, Numerical Investigation of Mixed Convection Heat Transfer in a Horizontal Channel with a Built-in Square Cylinder, ** Numerical Heat Transfer** - Part A, vol. 18, pp. 173-188, (1990).

A. Mukhopadhyay, G. Biswas and T. Sundararajan, Numerical Investigation of Confined Wakes Behind a Square Cylinder in a Channel, ** International Journal for Numerical Methods in Fluids**, vol. 14, pp. 1473-1484, (1992).

S. Singh, G. Biswas, and A. Mukhopadhyay, Effect of Thermal Buoyancy on the Flow through a Vertical Channel with a built-in Circular Cylinder, ** Numerical Heat Transfer**, Part A, Vol. 34, pp. 769-789, (1998)

A.K. Saha, K. Muralidhar,and G. Biswas, Vortex Structures and Kinetic Energy Budget in Two-Dimensional flow Past a Square Cylinder, ** Computers and Fluids** , Vol. 29, pp. 669-694, (2000).

A.K. Saha, G. Biswas and K. Muralidhar, Numerical Study of the Turbulent Unsteady Wake Behind a Partially Enclosed Square Cylinder using RANS, ** Computer Methods in Applied Mechanics and Engineering**, Vol. 178, pp. 323-341, (1999).

A.K. Saha, K. Muralidhar,and G. Biswas, Transition and Chaos in Two-Dimensional Flow Past a Square Cylinder, ** Journal of Engineering Mechanics (ASCE)**, Vol. 126, pp. 523-532, (2000).

A.K. Saha, G. Biswas, and K. Muralidhar, Two-Dimensional Study of the Turbulent Wake Behind a Square Cylinder Subject to Uniform Shear, ** Journal of Fluids Engineering (ASME)**, Vol. 123, pp. 595-603, (2001).

A. K. Saha, G. Biswas, and K. Muralidhar, Three-dimensional Study of Flow Past a Square Cylinder at Low Reynolds Numbers, ** Int. J. Heat and Fluid Flow**, Vol. 24, pp. 54-66, (2003).

A. K. Saha, K. Muralidhar and G. Biswas, Investigation of Two-and Three Dimensional Models of Transitional Flow Past a Square Cylinder, ** Journal of Engineering Mechanics (ASCE)**, Vol. 129, pp. 1320-1329, (2003).

G. Biswas, M. Breuer and F. Durst, Backward-Facing Step Flows for Various Expansion Ratios at Low and Moderate Reynolds Numbers, ** Journal of Fluids Engineering (ASME)**, Vol. 126, pp. 362-374, (2004).

R. Ranjan, A. Dalal and G. Biswas, A Numerical Study of Fluid flow and Heat Transfer around a Square Cylinder at Incidence using Unstructured Grids, ** Numerical Heat Transfer** Part A, Vol. 54, pp. 890-913, (2008).

N. Senthil Kumar and G. Biswas, A Finite Element Study of the Onset of Vortex Shedding in a Flow Past Two-dimensional Circular Cylinder, ** Progress in Computational Fluid Dynamics**, Vol. 8, pp. 288-298, (2008).

G. Biswas and S. Sarkar, Effect of Thermal Buoyancy on Vortex Shedding Past a Circular Cylinder in Cross Flow at Low Reynolds Numbers, ** International Journal of Heat and Mass Transfer**, Vol. 52, pp. 1897-1912, (2009).

S. Sen, S. Mittal and G. Biswas, Steady Separated Flow Past a Circular Cylinder at Low Reynolds Numbers, ** Journal of Fluid Mechanics**, Vol. 620, pp. 89-119, (2009).

D. Chatterjee, G. Biswas and S. Amiroudine, Numerical simulation of flow past row of square cylinders for various separation ratios, ** Computers and Fluids**, Vol. 39 pp. 49–59, (2010)

S. Sarkar, A. Dalal and G. Biswas, Unsteady wake dynamics and heat transfer in forced and mixed convection past a circular cylinder in cross flow for high Prandtl numbers, ** International Journal of Heat and Mass Transfer**, Vol. 54, pp. 3536–3551 (2011).

S. P. Singh and G. Biswas, Vortex induced vibrations of a square cylinder at subcritical Reynolds numbers, ** Journal of Fluids and Structures**, Vol. 41, pp. 146-155, (2013)

S. P. Singh, G. Biswas and P. Nithiarasu, A numerical study of vortex shedding from a circular cylinder vibrating in the in-line direction, ** International Journal of Numerical Methods for Heat & Fluid Flow**, Vol. 23, pp. 1449 - 1462, (2013).

S. Sarkar, S. Ganguly, G. Biswas and P. Saha, Effect of cylinder rotation during mixed convective flow of nanofluids past a circular cylinder, ** Computers and Fluids**, Vol. 127, pp. 47-64 (2016)

#### 6. Flows in Turbomachinery

Professor Biswas has developed Finite Element based methods to analyse flows in the complex passages in hydraulic turbomachines. He has implemented a rather intricate concept, Streamline-Upwind Petrov-Galerkin method, in a complex three-dimensional geometry to find out the nuances of flow physics. Notable mentions in this area are:

G. Biswas, V. Eswaran, G. Ghai and A. Gupta, A Numerical Study on Flow Through the Spiral Casing of a Hydraulic Turbine, ** International Journal for Numerical Methods in Fluids**, Vol. 28, pp. 143-156, (1998).

P.K. Maji and G. Biswas, Three-dimensional Analysis of Flow in the Spiral Casing of a Reaction Turbine using a Differently Weighted Petrov Galerkin Method, ** Computer Methods in Applied Mechanics and Engineering**, Vol. 167/ 1-2, pp 167-190, (1998).

P.K. Maji and G. Biswas, Analysis of Flow in the Spiral Casing Using a Streamline Upwind Petrov-Galerkin Method, ** International Journal for Numerical Methods in Engineering**, Vol. 45, pp. 147-174, (1999).

P.K. Maji and G. Biswas, Analysis of Flow in the Plate-Spiral of a Reaction Turbine Using a Streamline Upwind Petrov-Galerkin Method, ** International Journal for Numerical Methods in Fluids**, Vol. 34, pp. 113-144, (2000).

#### 7. Study of Turbulence Transport using Large-eddy Simulation

Large-eddy simulation is state-of-the-art and one of the most elegant methods for analysing turbulent flows. Professor Biswas is among the first group of researchers in India who started large-eddy simulation for impinging jets and bluff body flows. Identification of mechanism of separation, capturing coherent structures, near and far-wake dynamics have been analysed with insightful description concerning physics of flow and heat transfer. Some publications worth mentioning are:

T. Cziesla, G. Biswas, H. Chattopadhyay and N.K. Mitra, Large-Eddy Simulation of Flow and Heat Transfer in an Impinging Slot Jet, ** Int. J. Heat and Fluid Flow**, Vol. 22, pp. 500-508, (2001).

H. Chattopadhyay, G. Biswas and N.K. Mitra, Heat Transfer from a Moving Surface due to Impinging Slot Jets, ** Journal of Heat Transfer (ASME)**, Vol. 124, pp. 433-440, (2002).

Y. Srinivas, G. Biswas, A.S. Parihar and R. Ranjan, Large-Eddy Simulation of High Reynolds Number Turbulent Flow Past a Square Cylinder, ** Journal of Engineering Mechanics (ASCE)**, Vol. 132, pp. 327-335, (2006).

**, Vol. 53, 4856 – 4863, (2010)**

*International Journal of Heat and Mass Transfer*P. Saha, G. Biswas, A.C. Mandal and S. Sarkar, Investigation of coherent structures in a turbulent channel with built-in longitudinal vortex generators, ** International Journal of Heat and Mass Transfer**, Vol. 104, pp. 178-198, (2017).

#### 8. Microfluidics

Microfluidics is emerging as one of the most promising areas of Engineering Science that finds plenty of applications in Biosciences and Bioengineering and Nanotechnology. Professor Biswas is working in this exciting area through a collaborative approach. The collaborators are primarily the colleagues in IIT Guwahati, CSIR-Central Mechanical Engineering Research Institute, Durgapur and IIT Kharagpur. Some noteworthy publications are:

R.K. Arun, K. Chaudhury, M. Ghosh, G. Biswas, N. Chanda and S. Chakraborty, Controlled splitting and focusing of a stream of nanoparticles in a converging-diverging microchannel, ** Lab on a Chip**, Vol. 14, pp. 3800-3008, (2014).

A. Hens, K. Mondal, G. Biswas and D. Bandyopadhyay, Pathways from disordered to ordered nanostructures from defect guided dewetting of ultrathin bilayers, ** Journal of Colloid and Interface Science**, Vol. 465, pp. 128–139 (2016)

R. K. Arun, N. Priyadarshini, K. Chaudhury, N. Chanda, G. Biswas and S. Chakraborty, Paper-PDMS hybrid microchannel: a platform for rapid fluid-transport and mixing, ** J. Micromech. Microeng**., Vol. 26, 105008-1—105008-9, (2016).

R.K. Arun, P. Singh, G. Biswas, N. Chanda and S. Chakraborty, Energy generation from water flow over a reduced graphene oxide surface in a paper–pencil device, ** Lab-on-a-Chip**, vol. 16, pp. 3589-3596, (2016).

#### 9. Thermal Hydraulics of Nuclear Reactors

The mechanical design of the target module of an accelerator driven sub-critical nuclear reactor system (ADSS) calls for an analysis of the related thermal–hydraulic issues because of the sheer large amount of heat generation in its spallation target system during the course of nuclear interactions with the molten lead bismuth eutectic (LBE) target. The window of the target module is subject to high heat fluxes due to the direct impingement of high energy proton beam on its surface. Through a series of investigations, the equations governing the flow and thermal energy are solved using the streamline upwind Petrov–Galerkin (SUPG) finite element (FE) method. Special consideration has to be given to the window under various thermal conditions, such as, isothermal, uniform and variable heat flux. Some notable contributions in this area are:

K. Arul Prakash, G. Biswas and B.V. Rathish Kumar, Numerical Prediction of Fluid Flow and Heat Transfer in the Target System of an Axisymmetric Accelerator Driven Subcritical System, ** Journal of Heat Transfer (ASME)**, Vol. 129, pp. 582-588, (2007).

K. Arul Prakash, G. Biswas and B.V. Rathish Kumar, Thermal Hydraulics of the Spallation Target Module of an Accelerator Driven Sub-critical System: A Numerical Study, ** International Journal of Heat and Mass Transfer**, Vol. 49, pp. 4633-4652, (2006).

K. Arul Prakash, G. Biswas and B.V. Rathish Kumar, Numerical Simulation of the Target System of an ADSS, ** International Journal of Computational Fluid Dynamics**, Vol. 20, pp. 513-520, (2006).

K. Arul Prakash, S. De, B.V. Rathish Kumar and G. Biswas, A SUPG – Finite Element Study of an ADSS, ** Finite Element in Analysis and Design**, Vol. 42, pp. 1123-1136, (2006).

#### 10. Algorithm Related Work

A numerical method for predicting viscous flows in complex geometries was developed through integral mass and momentum equations discretized into algebraic form using numerical quadrature by Professor Biswas and his colleagues. The method has significant novelty and advantage for solving NS equations in complex geometry. Some worthy mentions in this field are:

A. Mukhopadhyay, T. Sundararajan and G. Biswas, An Explicit Transient Algorithm for Predicting Incompressible Viscous Flows in Arbitrary Geometry, ** International Journal for Numerical Methods in Fluids**, vol. 17, pp. 975-993, (1993).

A novel finite-volume formulation was proposed (based on an original contribution of Prof. V. Eswaran) for unsteady solutions on complex geometries. A computer code based on a cell-centered finite-volume method was developed to solve both two-dimensional (2-D) and three-dimensional (3-D) Navier-Stokes equations for incompressible laminar flow on unstructured grids.

A. Dalal, V. Eswaran and G. Biswas, A Finite Volume Method for Navier-Stokes Equations on Unstructured Meshes, ** Numerical Heat Transfer Part B**, Vol. 54, pp. 238-259, (2008).

The accurate calculation of the interface remains a problem for the volume-of-fluid method if the surface tension force plays an important role and the density ratios of the fluids in different phases are high. The result can be an artificial velocity field at the interface (parasitic currents), which can destabilize the interface significantly. The three different algorithms compared can be distinguished by their methods to compute the surface tension force, namely, the method using a kernel function for smoothing the discontinuity at the interface, a combined level-set and volume-of-fluid approach and a parabolic reconstruction of surface tension.

D. Gerlach, G. Tomar, G. Biswas, and F. Durst, Comparison of Volume-of-Fluid Methods for Computing Surface Tension-Dominant Two-Phase Flows, ** International Journal of Heat and Mass Transfer**, Vol. 49, pp. 740-754, (2006).

G. Tomar, D. Gerlach, G. Biswas, N. Alleborn, A. Sharma, F. Durst S. W. J. Welch, and A. Delgado, Two-phase Electrohydrodynamic Simulations Using a Volume-of-Fluid Approach, ** Journal of Computational Physics**, Vol. 227, pp 1267-1285, (2007).

#### Other notable contributions

In addition to the above areas, Professor Biswas has done some collaborative research with Professor Ashutosh Sharma is the area of de-wetting of thin polymeric coating on a low energy surface. They have shown by performing linear stability analysis that the pattern-wavelength is independent of viscoelasticity (Oldroyd-B fluid) and depends only on the surface tension coefficient, film thickness and the effective Hamakar constant.

Some other research contributions can be described as the following:

The liquid-side mass transfer rate in a centrifugal gas-liquid contactor has been reported to be several times higher than that in conventional packed beds. The technique finds application in Higee Separation Process:

P. Sandilya, G. Biswas, D.P. Rao and A. Sharma, Numerical Simulation of the Gas Flow and Mass Transfer between Two Coaxially Rotating Disks, ** Numerical Heat Transfer, Part A**, Vol. 39, pp. 285-305, (2001).

The influence of thermocapillary or Marangoni convection on the growth of silicon crystals is investigated in an industrial Czochralski crucible using a quasi-direct numerical simulations approach.

V. Kumar, G. Biswas, G. Brenner and F. Durst, Effect of Thermocapillary Convection in an Industrial Czochralski Crucible: Numerical Simulation, ** International Journal of Heat and Mass Transfer**, Vol. 46, pp. 1641-1652, (2003).

One of the recent investigations of Professor Biswas describes the laminar-to-turbulent transition of pipe flows through puff and slug structures. Together with Professor Franz Durst, he has shown that with increasing Reynolds number, ‘puff splitting’ is observed and the split puffs develop into slugs. Thereafter, the laminar-to-turbulent transition occurs in the same way as found for slug flows:

M. Nishi, B. Uensal, F. Durst and G. Biswas, Laminar-to-Turbulent Transition of Pipe Flows through Puffs and Slugs, ** Journal of Fluid Mechanics**, Vol. 614, pp. 425-446, (2008)