Dr. Arvind Kumar Bairwa

 

Brief Details:

A researcher with a Ph.D. in Hydrodynamics and Stochastic Transport Modeling from IIT Delhi (2015-2024). His doctoral research focused on developing/ introducing novel models for upscaling transport in crowded flow domains, such as vegetation patches and farm rings in shallow water bodies. Dr. Bairwa also worked as an Early Doc Fellow (July-October 2024) at IIT Delhi, where he delved deeper into advanced flow simulation. His work has been published in prestigious journals such as Stochastic Environmental Research and Risk Assessment and Physics of Fluids, with additional manuscripts in preparation. Dr. Bairwa has a strong background in nonlinear dynamics and stochastic processes, utilizing advanced mathematical tools from interdisciplinary fields to diagnose and understand complex problems. He is proficient in scientific computing tools such as MATLAB.

Before his Ph.D., he completed his MTech in Water Resources from IIT Delhi (2012-2014), where his project focused on scaling issues in intensity-duration-frequency curves. His work, based on fractal analysis of rainfall patterns at four gauging stations, earned him the highest grade and was published in the prestigious Journal of Hydrology (JOH). In addition to his academic work, Dr. Bairwa has been actively involved in extracurricular activities, serving as the Hostel Program Coordinator and House Day Program Coordinator at IIT Delhi. He also assisted in organizing the International Workshop on Coastal and River Zone Management. During his time at IIT Delhi, Dr. Bairwa was also a member of a music band and enjoys playing the guitar. Dr. Bairwa completed his Bachelor of Engineering in Civil Engineering (2008-2012) from M.B.M. Engineering College, Jodhpur.

Research: Mixing and Anomalous Transport in Aquatic Flow Domain With Crowding.

Arrays of solid bodies, such as vegetation patches and circular cage farm rings, are commonly found in shallow water lakes, rivers, and ponds. Understanding the mixing and transport of passive scalar species in these environments is critical for effective conservation and restoration efforts. However, the spatial and temporal complexity of the velocity field and storage effects due to obstructed flow often lead to non-Fickian (anomalous) transport behavior. In contrast to conventional Fickian (Gaussian) transport, where the mean square displacement (MSD) increases linearly with time and breakthrough curves (BTCs) exhibit exponential decay, non-Fickian transport shows a non-linear increase in MSD and long tail decay in BTCs. This anomalous behavior presents a significant challenge in predicting transport in these complex aquatic domains.

To address this challenge, we conduct high-resolution 2-D numerical simulations of flow through an array of cylinders with varying density and spacing. This array of cylinders serves as a simplified model for realistic bluff bodies in aquatic systems. In the first part of the talk, we utilize two coherent structure approaches—the Q-criterion and Finite-Time Lyapunov Exponent (FTLE)—to analyze the flow. Our findings demonstrate that as cylinder spacing decreases and density increases, coherent structures become suppressed, which significantly impacts mixing within the array, as identified by FTLE analysis. In the second part, we explore the limitations of the classical Advection-Dispersion Equation (ADE) in modeling transport through the cylinder array. Our Lagrangian particle tracking models reveal significant deviations from Fickian transport, as indicated by MSD and BTC behavior, highlighting the inadequacy of the ADE for these complex configurations. To address this, we propose an alternative framework based on the Continuous Time Random Walk (CTRW) model, which offers a more accurate and robust description of transport in these intricate aquatic flow domains.

Teaching: Lagrangian and Eulerian time derivative; Eulers equation and Bernoulli equations

In the 15 minute session, I will teach the fundamental concepts of the Lagrangian and Eulerian frameworks for studying fluid motion, explaining both the physical intuition and the mathematical derivation of their respective derivatives. Building on this foundational understanding, I will then derive and discuss Euler’s (inviscid) equation, presenting it as an application of Newton's second law of motion to fluid dynamics. I will end the talk by concluding one of the important results of Euler's equation, which is Bernoulli's equation, and discuss its practical application in water resources system.