Inauguration of our Raindrops Research Facility (RRF)
on 3rd Feburary 2023
by Dr. V. K. Saraswat, Hon'ble Member, NITI Aayog
in the august presence of
Prof. B. S. Murty, Director, IIT Hyderabad
Prof. M. Vidyasagar, FRS

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Research interests

Applications

Clouds and raindrops

Accurate weather forecasting and precipitation modelling heavily rely on understanding the shape and size of raindrops, which are influenced by microphysical processes like condensation/evaporation, coalescence, and fragmentation. These processes, in turn, can be affected by temperature, air currents, and humidity gradients. Neglecting droplet coalescence and breakup alone can lead to a 10% error in rainfall modelling without considering the impact of phase change, which is also significant. To address these challenges, we have developed a state-of-the-art experimental facility that simulates the atmospheric conditions of raindrops descending from a cloud to the ground, allowing us to study the impact of microphysical processes on droplet dynamics. Our facility is designed and constructed from scratch and can be integrated with weather radar technology to enhance forecast accuracy.

Bubble dynamics

Bubbles and drops have been the subject of investigation for centuries and remain a topic of great interest today due to their significance in natural phenomena, including aerosol transfer from the sea, oxygen dissolution in lakes due to rain, and electrification of the atmosphere by sea bubbles. They also play a critical role in various industrial processes, such as bubble column reactors, the petroleum industry, the flow of foams and suspensions, and carbon sequestration. Despite the vast literature on this subject, many unsolved problems persist. See our publication in Nature Communications (2015).

Viscosity-stratified flows

Variations in viscosity, both over time and in space, have the potential to significantly impact fluid flow in various applications, such as the Earth's mantle, chemical industry, and dynamics of objects entering the planetary atmosphere. As seen in non-Newtonian fluids like blood and mucus, shear and its past can affect viscosity. Our focus is on investigating hydrodynamic instabilities that arise in viscosity-stratified flows, which can be utilized to enhance mixing or decrease drag in diverse industrial settings. See our publication in Annual Review of Fluid Mechanics (2014).

Small-scale flows

The instabilities of the spatially developing laminar flows are shown to be fundamentally different from flows that do not vary downstream. The base flow itself is quite complicated and needs to be computed very accurately, given that the stability is very sensitive to the base flow. We are interested in studying the linear evolution by considering the non-parallel stability analysis and, subsequently, the nonlinear effect using direct numerical simulation. As such flows are unstable at surprisingly low Reynolds numbers, it can improve mixing in microfluidic devices, which is challenging. This instability mechanism can enhance mixing or reduce drag in a wide range of industrial applications.

Numerical solvers for multiphase flows

We have developed various computational fluid dynamics solvers utilizing different approaches, such as volume-of-fluid, diffuse-interface, and lattice Boltzmann methods. We have also incorporated the Graphics Processing Unit (GPU) as a new scientific computing paradigm. Our GPU-based flow solver has demonstrated a 25-fold increase in speed compared to a CPU-based flow solver. Furthermore, connecting multiple GPUs in a cluster can provide even greater acceleration. Consequently, this innovative implementation offers significant advantages in terms of the complexity and size of the problems we can tackle.