Research Themes
Multiphase Flows | Renewable Energy | Atmospheric and Oceanic Turbulence
Multiphase Flows | Renewable Energy | Atmospheric and Oceanic Turbulence
Project Overview: Renewable energy has become vital to fulfill global energy demands without adversely affecting the environment. Offshore wind farms have the potential to harness vast amounts of clean energy, but their performance and efficiency are greatly influenced by complex interactions between the wind, the sea surface waves, and offshore structures. Understanding and modeling these wind-wave interactions is of paramount importance to optimize the design and operation of offshore wind energy systems. Our goal is to characterize processes in the marine atmospheric boundary layer using high-fidelity numerical simulations to study the complex wind-wave-wake interactions enabling realistic predictions of wind farm power and turbine loads. These advances will be a step towards achieving the goal of net-zero emissions by 2050, thereby decreasing the carbon footprint of our energy system.
Project Overview: Bubbles, drops, and particles play a critical role in numerous environmental processes, such as the dispersion of sediment, microplastic, and biological matter in the oceans. Understanding particle-scale phenomena such as gravitational settling, break-up, evaporation, and coalescence that occur in the presence of large-scale flows due to the complex interplay between the flow, buoyancy, capillarity, and viscous forces is of primary importance. We use a combination of detailed numerical simulations (Euler-Euler LES) to model multiphase systems across various scales, developing important computational tools and theories in the process.
Project Overview: The interaction of ocean waves and structures is a fundamental problem in engineering, spanning disciplines such as renewable energy, oil and gas, civil engineering, and infrastructure development. Understanding wave-structure interactions is multifaceted and requires an accurate determination of the sea state, the forces exerted on extended structures, and the turbulent nature of the fluid-structure interactions. We aim to elucidate these complex interactions and develop a sea-state-dependent model to calculate impact loads, which are crucial in the design of marine structures. Our long-term goal is to gain a fundamental understanding of the wake characteristics and dynamic loading of offshore structures in realistic environments. We seek to leverage this understanding to formulate reliable parameterizations relevant to both deep and shallow offshore conditions, where significant efforts to install renewable energy systems (marine and wind energy) are being undertaken
An elegant model for passive scalar mixing was given by Kraichnan assuming the velocity field to be delta-correlated in time. We extended this model for more realistic flows, i.e. velocity fields with a finite correlation time using the generalized evolution equation for the three-dimensional passive scalar spectrum. For leading order in time the scalar spectrum in the viscous-convective (Batchelor) regime decreases linearly with wave number, independent of the correlation time. Additionally, the long-time behavior of the decaying passive scalar spectrum is also independent of the time tau. The scaling of the steady state and decaying spectra were then verified using direct numerical simulations.
Aiyer, A. , Subramanian K., & Bhat, P. "Passive scalar mixing and decay at finite correlation times in the Batchelor regime." Journal of Fluid Mechanics, 824, 785-817