Engineering Mechanics Unit

The Engineering Mechanics Unit pursues research on a variety of problems of fundamental and applied interest in fluid mechanics, nonlinear dynamics, heat transfer and solid mechanics using a wide range of analytical, numerical and experimental techniques. Fluid mechanics research conducted in the Unit spans a wide range of topics, from understanding flows on geo- and astro-physical scales to those at the nanoscale. Research in non-linear dynamics includes solar system dynamics, vortex dynamics, and geometric interpretation of the ideal fluid equations. Radiative and convective heat transfer, especially in the atmosphere, is another area of active research.

We work on mechanical and real swimmers and fliers, including bacteria, insects, aircraft and submarines. We examine flows of microstructured complex fluids and stratified fluids. Examples of the former include clay suspensions, aerosols, emulsions, granular media and polymer solutions, while the atmosphere, the oceans and volcanic flows are excellent examples of stratified systems occurring in nature.

The emphasis in all cases is on a fundamental understanding of the physical mechanisms operating at both large and small scales. We also work on complex flows of a simple fluid such as water arising as a consequence of an instability. The idea is then to understand how a flow or a system becomes unstable and goes to a new, possibly chaotic or turbulence-like state. The choice of problems is often inspired by potential applications, in understanding nature or in developing technology.

The Unit’s technologically oriented studies primarily focus on aerospace and chemical applications. For example, studies on flow stability and transitions between laminar and turbulent states in a wide variety of situations have direct relevance to aerospace and chemical technologies. New insights into the action of polymers on turbulent flows – as well as the nature of transition on swept wings – have been obtained from such work. Another area of special interest is computational fluid dynamics, chiefly in problems connected with aerospace technology. Research on the dynamics of granular media explores fundamental scientific problems and also have direct applications in chemical and other technologies.

Biological problems and natural phenomena – from insect flight to the fluid dynamics of clouds – are being investigated by employing both theoretical and experimental methods. Using wavelets as a tool, faculty members in the Unit have analysed the temporal structure of monsoon rainfall, revealing a possible link to solar activity at vastly higher levels of statistical significance than had previously been possible. Another area of research, chiefly of geophysical interest, is double diffusive convection, which is being investigated through experiments as well as numerical simulations. Research on insect flight – which involves both experiments in a wind tunnel using particle image velocimetry techniques and also computer simulations with discrete vortices – is shedding light on the underlying mechanisms of flight. This work is also relevant to the design of micro air vehicles, which is now an area of considerable technological interest. Additionally, since clouds exhibit unusual characteristics in entrainment of ambient air, current research in the Unit explores this interesting phenomenon.

The Unit’s faculty members are engaged in extensive collaborations with scientists located elsewhere in India and abroad. Examples of recent collaborations within India have been with National Aerospace Laboratories (NAL) and IISc Bangalore; international collaborations include those with Queen Mary and Westfield College (UK), QinetiQ (UK), Boeing Research Centre (USA), the Weizmann Institute (Israel) and the University of Stuttgart (Germany). In a collaborative project with scientists at the NAL, it has been shown that a Navier-Stokes code properly optimized for a parallel computer (the Flosolver built at NAL) has led to super linear speed-up, giving a factor of 11 on 8 processors.

The EMU’s on-site facilities support the faculty members’ broad experimental and theoretical research interests. Experimental facilities include a low-speed wind tunnel, which has a transparent test section of 2 m length and 0.6 m x 0.6 m cross-section. This tunnel can be operated with uniform velocities from 1m/s up to 10 m/s. An Nd-Yag laser (10 Hz, 120 mJ/pulse) is part of a Particle Image Velocimeter that yields instantaneous velocities in a plane. Computing facilities of the Unit include a computer centre with several PCs, an eight-node Flo-solver Mk6 system, and a six-node Xeon processor cluster.

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