A range of fluid mechanics phenomena are being studied within the Department using both experimental and computational techniques. Prof. Jaywant Arakeri and his group has been actively carrying out experimental research in turbulent natural convection since the late 1980s. His activities have now been diversified into applied areas such as precision agriculture in protected environments. The experimental capability of the fluid mechanics team was enhanced after the joining of Prof. R.N. Govardhan in the early 2000s. His areas of interest include drag reduction, interaction of vortex with bubbles, turbomachinery flutter and shock boundary layer interactions. The computational strength of the fluid mechanics group was enhanced after Prof. Ratnesh K. Shukla and Prof. Gaurav Tomar joined the faculty. Together, they cover a wide range of topics in computational fluid dynamics (CFD) involving multiscale, multiphase and complex non-Newtonian flows.  Prof. Aloke Kumar has recently joined this group, introducing the relatively nascent area of complex fluids.

The experimental and computational teams are now collaborating on a number of difficult and interesting fluid dynamics problems such as optimal surface actuation for drag reduction, thrust from rigid/flexible flapping foils for ‘robotic fish’, and biofluid mechanics involving flexible surfaces and unsteady boundary layers. A brief account of some of the exciting developments that have resulted is summarized below, with the topics being roughly ordered in decreasing order of interest – starting from turbulent convection at the geophysical scale to multi-scale simulations using molecular dynamics at the atomic/molecular level.

Activities on heat transfer and energy systems in the Department were initiated by Prof. Arcot Ramachandran in the 1960s as a pioneering initiative which led to the establishment of major programmes in energy research across the country. Today, the research group in thermal sciences and energy systems is the largest one in the Department, and has contributed significantly in basic and applied research. The newly founded Interdisciplinary Centre for Energy Research (ICER) at IISc emerged out of this group’s efforts. This centre handles some of the biggest projects in the Institute, namely the Indo-US solar consortium (SERIIUS), the National Centre for Combustion Research and Development (NCCRD) and the National Centre for Clean Coal Research and Development (NCCCRD).

Present activities in Prof. Pradip Dutta’s lab include development of cooling technologies (adsorption cooling, loop heat pipes, phase change materials) and development of high-temperature solar thermal receivers along with thermo-chemical storage technologies.  Prof. R.V. Ravikrishna initiated combustion research activities, which was subsequently augmented by Prof. Saptarshi Basu’s lab. In this area, topics include spray dynamics and atomization, trapped vortex combustion, research on fuel injectors for gas turbine combustion, laser diagnostics, and combustion from levitated droplets. Prof. Pramod Kumar has developed India’s first supercritical CO₂ (s-CO₂) Brayton test loop for power generation and is developing micro-channel heat exchangers for s-CO2. Research on IC engines is being carried out by Dr. Himabindu and Dr. R.T. Naik. Dr. G.S.V.L. Narasimham’s lab works on cooling technologies and refrigeration. Our recent addition, Dr. Susmita Dash, specializes in microscale thermal transport.

In addition to fundamental research, the group has also actively collaborated with industries for technology development and translational research. Notable among them are development of s-CO₂ turbomachinery with Triveni Turbines (Prof. Kumar), successful flight testing of loop heat pipe by ISRO (Prof. Dutta), development of molten salt based thermal storage loop with HPCL (Prof. Basu) and development of natural gas combustor for s-CO₂ power cycle with GAIL (Prof. Ravikrishna).

Research groups in the area of manufacturing and materials aim to foster advanced research in the understanding of fundamental mechanisms that govern materials design, materials processing, component design, and manufacturing processes and systems. A second direction is to advance the state-of-the art in materials and manufacturing technology. The labs are accordingly equipped with a vast array of characterization tools that includes scanning electron microscopes, atomic force microscopes, contact angle goniometer, differential scanning calorimeter, dynamic light scattering particle analyzer, Fourier transform infrared spectrometer, 3-D optical profilometer, optical microscopes and universal testing machines.

Prof. Satish V. Kailas’s group has made extensive contributions to the Department’s capabilities in tribology. To that end, several machines are custom-built to simulate conditions for the tribological systems under study. For example, a fretting wear tester that works under vacuum and high temperature has been built to simulate conditions of a fast breeder reactor where the primary and secondary loops work under liquid sodium and at 550 ⁰C.  Several other machines like the high-temperature vacuum-based pin-on-disc machine to mimic conditions in a bearing channel during extrusion, and impact tribometer to study tribological phenomena during the start of sliding have been designed and built. Another concentration of Prof. Kailas is the area of friction stir welding and processing. Prof. M.S. Bobji examines the world of micro- and nano-forces to assess the behaviour of materials at small scales in real time. His group is currently invested in developing special tools to mechanically, electrically and thermally probe things. Prof. Koushik Viswanathan who has recently joined the Department studies the mechanics and physics of manufacturing processes with a focus towards development of new paradigms that address the demands of emerging technologies. Collaborative efforts of the Department faculty with other departments across the Institute are ongoing.

Mechanics of solids caters to a longstanding interest of the Department, spanning multiple scales (macro to micro) and multiple domains (fracture, MEMS, biomechanics). Work in this broad area includes analytical, computational, and experimental research projects. Prof. K.R.Y. Simha studies fracture in thin-film coating, dynamic loading on plates and shells for impact-resistant shields, and more recently, fracture in friction-stir welded joints. Prof. R. Narasimhan’s group has been actively involved in analytical, experimental and computational studies on crack-tip fields and void growth in ductile face-centered cubic (FCC) single crystals. These investigations have established the structure of these fields for different lattice orientations, constraint levels and fracture configurations. He has also been working on the role of several factors such as pressure-sensitive yielding, internal friction, flow softening, Poisson’s ratio and mode-mixity in the fracture response of bulk metallic glasses (BMGs). Prof. C.S. Jog has made substantial strides on the formulation of the finite element method with the implementation of hybrid elements, wherein displacement and stress are independently interpolated for computational benefits in multiphysics simulations.

In addition to extensive research in fracture and computational mechanics, recently a number of faculty are exploring other aspects of solid mechanics. Prof. Namrata Gundiah is engaged in experimental and computational work in biomechanics of tissue and cells. She has also studied the mechanics of insect boring. Prof. Ramsharan Rangarajan conducts research aimed at probing the role of geometry in slender structures such as beams, ribbons, and shells. Prof. G.K. Ananthasuresh’s group studies mechanics-based design of compliant mechanisms, growth modeling in plant leaves and inverse problems in elastic mechanics. His group has ongoing work in multiple pathways in bistable arches and shells with innovative designs of devices that exploit this feature.

A number of groups in the Department are engaged in research on micro- and nanoscale phenomena. Beginning with microelectromechanical systems (MEMS), one of the first such groups in India led by Prof. Rudra Pratap whose group investigated dissipation in MEMS devices, micro and nano research in the Department has grown in multiple directions. Topics like mechanics of solids and fluids at small length scales, microscale transport phenomena, computational micromechanics, development of numerous micro sensors and actuators, etc. have been vigorously pursued in the Department for more than 15 years now. These efforts are now growing rapidly with newly hired faculty, besides inter-departmental collaborative ventures.

It may be noted that MEMS as well as micro- and nano-fabrication research initiated and nurtured by the groups of Prof. Pratap and Prof. G.K. Ananthasuresh played an important role in launching the Centre for Nano Science and Engineering (CeNSE) in IISc in 2010. They are also responsible for expanding the scope of MEMS research across India through engagement in two national research missions, namely the National Programme on Smart Materials (NPSM) and the National Programme on Micro and Smart Systems (NPMASS). Alongside, Prof. M.S. Bobji has explored nanomechanics for over two decades now with novel experimentation in Transmission Electron Microscopy (TEM). Prof. Ananthasuresh, Prof. C.S. Jog and Prof. Pratap also led a multi-investigator project to develop a MEMS software suite for multiphysics simulation. Micromachined pressure sensors, accelerometers, gyroscopes, Capacitive Micromachined Ultrasonic Transducers (CMUTs), force sensors, xy-stages, RF switches, miniature grippers, micro-speakers, etc., were developed, tested and calibrated as part of this initiative. Some of these have been commercialized (e.g., pressure sensor, force sensor) while others are in the translation phase. More recently, new faculty like Prof. Saptarshi Basu, Prof. Aloke Kumar, and Prof. Susmita Dash have shown keen interest in research on fluids and heat transfer aspects at small length scales.

Research in vibrations and acoustics was started by Prof. M.L. Munjal almost fifty years ago in the Department. The objective was to design industrial products for quietness, with a strong focus on automotive mufflers. Computational and experimental work was carried out in the Ducts and Mufflers Laboratory in the Department leading to a commercial software that can predict the performance of industrial automotive mufflers.  In order to popularize technical acoustics for education and research, Prof. Munjal carried out industrial consultations and government projects, organized numerous workshops across the country, and offered continuing-education programs for college teachers. He was involved at the highest levels of government policy-making to bring forth noise-control norms across the country. It was only natural for him to register his vast expertise in a comprehensive book titled ‘Acoustics of Ducts and Mufflers’, published by John and Wiley. In 1999, he was joined by Prof. Venkata R Sonti, with a background in structural acoustics. Prof. Sonti and his students conduct analytical/semi-analytical studies on well-posed sound-structure interaction problems. Initially starting with linear problems, Prof. Sonti has broadened his interests to include nonlinear structural acoustic systems. More recently, there has been an energy initiative, wherein a part the objective is to understand the rotor dynamics of high-speed shafts (~ 70,000 rpm). Subsequent to these studies, research is expected to extend to the fluid-structure interaction domain.

Research activities in control in the Department have been marshalled by Prof. Ashitava Ghosal for close to three decades now, aligned with his longstanding interest in the field of robotics. He has served as instructor for the course “ME 240 Dynamics and Control of Mechanical Systems” for several years. The scope of control research was expanded to new regimes in 2018 when Prof. G.R. Jayanth joined the Department as Associate Faculty. Prof. Jayanth works on precision motion control, with applications in metrology and robotics, at the micrometer and nanometer length scales. Towards this end, his group is investigating development of new measurement techniques, probes, actuation techniques, and advanced control.