Thesis Colloquium / Defence

Nature has consistently served as a powerful source of innovation, offering elegant and sustainable solutions to complex engineering problems. Among these, the spinning samara seed stands out as a biologically efficient system for passive aerial transport. Samaras, such as those from mahogany and Buddha coconut trees, exhibit stable autorotative descent, making them strong candidates for […]

Bulk ferromagnetic materials exhibit Joule magnetostriction with characteristic strain magnitudes on the order of (10^{-6}) to (10^{-4}), which is often insufficient for the displacement requirements of modern soft robotic and adaptive structural systems. Ferromagnetic elastic slender structures provide a promising alternative, offering the potential for large actuation displacements under small external magnetic fields. This enhanced […]

The importance of transitional flow studies can be realized from the fact that it acts as a bridge between the laminar and turbulent flows. The present work deals with the investigation of time-frequency characteristics of transitional flows and their modelling, which is presented in three parts. First, we propose a wavelet-transform based smooth detector function […]

Multi-label learning (MLL) addresses learning problems in which a single data instance may simultaneously belong to multiple semantic categories. This formulation arises naturally in many real-world applications, including image and video understanding, medical diagnosis, text categorization, and bioinformatics. In many of these settings, it is not sufficient to merely rank relevant labels higher than irrelevant […]

Two supersonic streams merging together in a co-flow configuration are encountered in several engineering systems, such as high-speed propulsion devices and supersonic ejectors. The thin mixing layer that develops between the two streams is dominated by compressibility effects and is prone to shock interactions in shock-dominated flows. The convective Mach number is defined relative to […]

Shear stress at the wall is a quantity of fundamental importance in wall-bounded flows. It determines skin-friction drag and the dynamics of flow separation. From an engineering standpoint, it is a key parameter which dictates the overall aerodynamic performance and structural loading of flight vehicles. Hence, there is a natural motivation for the development of […]

A comprehensive investigation of the energy and enstrophy cascade in physical space in a turbulent channel flow is presented for four Reynolds numbers. Bandpass filtering techniques are employed to isolate scales and quantify inter-scale interactions through kinetic energy flux, enstrophy generation, and enstrophy flux. Two bandpass filter formulations used in the literature are quantitatively assessed by comparing the output. The mean energy and enstrophy cascades are shown to be predominantly local for all the Reynolds numbers. Away […]

Multi-agent systems are increasingly deployed in missions involving large-scale tasks with complex objectives that are beyond the capability of a single agent. Such missions demand computationally efficient coordination strategies that ensure safety, reliable operation, and ease of implementation, particularly in dynamic and uncertain environments. This thesis investigates coordination strategies in multi-agent systems, specifically addressing the […]

Hypersonic propulsion systems capable of sustained atmospheric flight are critical enablers for future reusable launch vehicles, long-range high-speed transport, and responsive global strike platforms. Among the various air-breathing concepts, scramjet engines offer unmatched efficiency at hypersonic speeds by utilizing atmospheric oxygen and avoiding the mass penalties associated with onboard oxidizers. However, the practical realization of […]

Gaseous and particulate pollutants pose a significant threat to human health and the environment, prompting regulatory action to address major sources of emissions. Soot is a key particulate pollutant. Recently, emission standards for commercial aeroengines have been revised, necessitating the mitigation of soot emissions. Investigating the soot formation process is a key step towards reducing […]

Boundary layer (BL) transition to turbulence occurs through the inception, growth, and merging of turbulent spots. Understanding these spots is vital for predicting aerodynamic performance in disturbance-dominated environments like gas turbines. However, conventional spot identification has been limited by subjective, manual thresholding. The first phase of this work introduces a novel, threshold-free demarcation scheme combining […]