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X-ORIGINAL-URL:https://aero.iisc.ac.in
X-WR-CALDESC:Events for Department of Aerospace Engineering
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BEGIN:VTIMEZONE
TZID:Asia/Kolkata
BEGIN:STANDARD
TZOFFSETFROM:+0530
TZOFFSETTO:+0530
TZNAME:IST
DTSTART:20260101T000000
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BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20260105T110000
DTEND;TZID=Asia/Kolkata:20260105T130000
DTSTAMP:20260516T024150
CREATED:20260102T043026Z
LAST-MODIFIED:20260105T113025Z
UID:10000108-1767610800-1767618000@aero.iisc.ac.in
SUMMARY:Ph.D. (Engg) :Studies on the Mixing Layer Between Supersonic Supersonic Co-flows
DESCRIPTION: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 dominant large-scale structures in the mixing layer and is typically used to characterise the mixing layer. A key observation from previous studies on canonical supersonic-supersonic mixing layers having zero streamwise pressure gradient (ZPG-ML)\, which has a significant bearing on system design\, is that the growth of the mixing layer is significantly reduced as the convective Mach number increases. In applications\, however\, streamwise pressure gradients can exist due to the flow topology\, but there are very few studies on the effects of the streamwise pressure gradient on the growth of mixing layers (SPG-ML)\, especially in shock-dominated flows\, which motivates this study. Further\, there is a need to enhance mixing rates for compact design\, which can be carried out using passive geometric modifications\, and the effects of techniques such as discrete injection through holes and vortex generators like lobes on SPG-ML are not well studied. We study the mixing layer between supersonic-supersonic coflows in a specially designed supersonic mixing layer experimental facility\, and using high-fidelity Large Eddy Simulations carried out using the OpenFOAM framework. The Mach number combinations of the two streams (2.0\, 3.0) and (2.5\, 3.0)\, with a typical convective Mach number of 0.23\, are investigated. The flow is experimentally examined using high-speed schlieren and wall static pressure measurements. First\, the LES framework is validated on existing experimental/DNS computations on ZPG-ML\, and the computations are found to simulate the mixing layer characteristics well. The flow topology of the SPG-ML involves the generation of an oblique shock and an expansion fan at the point of confluence\, as well as the development of the mixing layer downstream in the presence of a streamwise pressure gradient. The shock further reflects from the wall and impinges on the mixing layer. The wall static pressure profiles obtained from the LES simulations agree well with the experimental wall static pressure measurements. The mixing layer growth rate of the SPG-ML before shock interaction is 15% higher than ZPG-ML. Shock interaction significantly increases the three-dimensionality of the turbulent structures in the mixing layer\, particularly in the p resence of high baroclinic torques\, and enhances the growth rate. In the current study\, the mixing layer is found to curve after the shock interaction\, thereby sustaining an increase in the mixing layer growth rate compared to previous studies. Two different techniques of introducing streamwise vortices into the mixing layer are investigated\, the first where discrete holes connect the high-pressure side to the low-pressure side\, leading to a jet into the supersonic stream\, generating counter-rotating vortices. In the second technique\, elliptic lobes generate large streamwise vortices. Both techniques are found to increase the mixing layer growth rate before the interaction. Shock interaction is found to break up vortices and promote three-dimensionality in the milder case of the jet through the holes. In the case of lobes\, the streamwise vortices are strong enough to retain their connectedness despite getting significantly modified by the shock interaction. These observations have implications for the application of such techniques to enhance mixing in shock-dominated flows. Detailed comparative investigations of different supersonic-supersonic mixing layer configurations are examined using experiments and LES data \n  \nSpeaker:  PANCHABUDHE LAKHAN MADANJI  \nResearch Supervisor: Srisha Rao M V
URL:https://aero.iisc.ac.in/event/ph-d-engg-studies-on-the-mixing-layer-between-supersonic-supersonic-co-flows/
LOCATION:STC Seminar Hall\, Dept. of Aerospace Engineering
CATEGORIES:Thesis Colloquium / Defence
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2026/01/PANCHABUDHE-.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20260105T150000
DTEND;TZID=Asia/Kolkata:20260105T170000
DTSTAMP:20260516T024150
CREATED:20260102T070038Z
LAST-MODIFIED:20260106T051847Z
UID:10000109-1767625200-1767632400@aero.iisc.ac.in
SUMMARY:Constructive Role of Noise in Oscillator Networks
DESCRIPTION:he constructive role of temporal disorder (random noise) in facilitating responses of nonlinear systems will be explored in this talk\, through a combination of experimental and numerical investigations. In particular\, nonlinear oscillators and nonlinear oscillator arrays will be considered. These oscillator systems represent models of micro-scale and macro-scale systems and energy harvester systems. It is discussed how noise can be used to transition from one dynamic to another\, including transition from a chaotic state to a periodic state\, influence energy localization\, and realize synchronization.\n\nSpeaker: Prof. B. Balachandran\n\nBiography:\n\nDr. Balachandran received his B. Tech (Naval Architecture) from the Indian Institute of Technology\, Madras\, India\, M.S. (Aerospace Engineering) from Virginia Tech\, Blacksburg\, VA and Ph.D. (Engineering Mechanics) from Virginia Tech. Currently\, he is a Distinguished University Professor and a Minta Martin Professor at the University of Maryland\, where he has been since 1993. His research interests include applied physics\, applied mechanics\, applied mathematics\, nonlinear phenomena\, dynamics and vibrations\, and control. The publications that he has authored/co-authored include a Wiley textbook entitled “Applied Nonlinear Dynamics: Analytical\, Computational\, and Experimental Methods” (1995\, 2004)\, a Thomson/Cengage textbook (2004\, 2009) and a Cambridge University Press textbook (2019) entitled “Vibrations\,” and a co-edited Springer book entitled “Delay Differential Equations: Recent Advances and New Directions” (2009). He holds four U.S. patents and one Japan patent\, three related to fiber optic sensors and two related to atomic force microscopy. He has served as the Editor of the ASME Journal of Computational and Nonlinear Dynamics\, a Contributing Editor of the International Journal of Non-Linear Mechanics\, and a Deputy Editor of the AIAA Journal. He is an ASME Fellow\, an AIAA Fellow\, an Honorary Fellow of the Royal Aeronautical Society\, an ASA full member\, and an IEEE Senior Member. He is a recipient of the ASME Melville Medal\, the Thomas Caughey Dynamics Medal\, the Den Hartog Award\, & the Lyapunov Award\, the ASCE Engineering Mechanics Institute Robert Scanlan Medal\, and the AIAA Pendray Aerospace Literature Award. He served as the Chair of the Department of Mechanical Engineering at the University of Maryland from May 2011 to December 2023 and ASME Applied Mechanics Division from 2018 to 2019.
URL:https://aero.iisc.ac.in/event/constructive-role-of-noise-in-oscillator-networks/
LOCATION:Auditorium (AE 005)\, Department of Aerospace Engineering
CATEGORIES:AE Seminar
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2026/01/Balachandran.jpg
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BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20260112T160000
DTEND;TZID=Asia/Kolkata:20260112T170000
DTSTAMP:20260516T024150
CREATED:20260109T053022Z
LAST-MODIFIED:20260112T112429Z
UID:10000110-1768233600-1768237200@aero.iisc.ac.in
SUMMARY:Ph.D. (Engg) : Compression & LVI of closed-cell metallic foam
DESCRIPTION:Innovative high-performance structural designs play a critical role in mitigating insecure events such as low-velocity and ballistic impacts. These events involve significant kinetic energies\, requiring structures that are lightweight\, safe\, and capable of absorbing energy effectively. Closed cell metallic foams have been widely adopted in aerospace\, marine\, civil\, mechanical\, and automotive industries due to their superior resistance to such impacts. Despite extensive research over the years\, further advancements are still required in the design of lightweight protective structures. In impact applications\, the impactor need not always strike perpendicular to the structure. Characterization of dissipation energies \, impact load histories\, and load–displacement curves under varying impact angles revealed\, Contact force intensity and penetration time decrease as the impact angle increases. Energy absorption increases while penetration time decreases with increasing impact angle. Contact force decreases and contact time increases as the angle decreases. Displacement under oblique impact increases with increasing angle. The study was extended to finite element simulations of low-velocity impact behaviour in silicon–aluminium composite foams using ABAQUS/Explicit®. Numerical estimations of both full and partial damage were carried out for different impactor shapes and velocities. Key parameters such as dissipation energies\, impact load histories\, and load–displacement behaviour under penetration were systematically reported. The numerical scheme was validated against available experimental results\, confirming the accuracy and reliability of the model. The following observations were made: Impact velocity effects: Contact force intensity and penetration time decrease with increasing impact velocity. Energy absorption increases while penetration time reduces as velocity increases. Impactor nose radius effects: Contact force reduces with smaller nose radii. Contact time is enhanced as the nose radius decreases. Impactor shape effects: The computed energy absorption effectiveness factor revealed that performance depends not only on material properties but is also strongly influenced by the geometry of the impactor. The study was further extended to numerical simulations of aluminium foam subjected to low velocity impacts. Both full and partial damage estimations were performed on foam samples across varying impact energies and thicknesses. Dissipated energy\, impact load histories\, and load–displacement responses were systematically reported under different penetration conditions. Foam samples with a thickness of 10 mm exhibited bending and global failure\, characteristic of thin plate behaviour. In contrast\, samples thicker than 10 mm underwent local failure\, displaying behaviour typical of thick plates. For partial penetration cases\, contact force\, dissipated energy\, deformation\, and penetration time all increased with rising impact energy. For fully penetrated samples\, contact force\, dissipated energy\, and deformation increased monotonically with impact energy\, while penetration time decreased significantly. Across all aluminium foam samples\, greater thickness led to monotonic increases in contact force\, dissipated energy\, deformation\, and contact time. These findings underscore the critical influence of plate thickness in governing the impact resistance of aluminium foam structures. Furthermore\, closed cell foam was modelled at the mesoscale to replicate the intrinsic geometry of real foam structures. LVT based 3-D models were employed to generate complex morphologies\, including irregular pore sizes\, uneven cell wall thicknesses & geometric variability. Morphological parameters such as equivalent diameter & sphericity factor were used to quantify pore size & irregularities. The influence of pore number & porosity on cell wall thickness was examined & the quasi-static compressive behaviour was assessed through load-displacement & stress-strain responses\, alongside energy absorption & plastic dissipated energies. Results revealed that plateau strength exhibited only a marginal increase with pore number\, while energy absorption showed a slight counterintuitive decline. Plastic dissipation energy increased monotonically with increasing pore number. Conversely\, increasing porosity led to a monotonic decrease in yield point\, energy absorption capacity & plastic dissipation energy. The study underscores that energy absorption capacity is strongly governed by porosity\, cell wall thickness & pore size. These parameters must be incorporated into the design of closed-cell foams to ensure safe & reliable performance in protective structural applications. \n  \nSpeaker: THIMMESH T \nResearch Supervisor: Dineshkumar Harursampath
URL:https://aero.iisc.ac.in/event/ph-d-engg-compression-lvi-of-closed-cell-metallic-foam/
LOCATION:STC Seminar Hall\, Dept. of Aerospace Engineering
CATEGORIES:AE Seminar
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2026/01/Thim.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20260116T160000
DTEND;TZID=Asia/Kolkata:20260116T170000
DTSTAMP:20260516T024150
CREATED:20260113T100659Z
LAST-MODIFIED:20260113T100659Z
UID:10000111-1768579200-1768582800@aero.iisc.ac.in
SUMMARY:Ph.D. (Engg) : Development of an ultra-miniature wall-shear-stress sensor
DESCRIPTION: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 new techniques and sensors that can offer well-resolved measurements of wall shear stress. Conventionally\, the techniques of hot-film anemometry and oil-film interferometry are used for wall-shear-stress measurements. These techniques\, however\, are severely limited in the spatio-temporal resolution that they can offer. Advances in micro and nano-fabrication techniques over the past three decades have led to the advent of MEMS-based floating element sensors. While MEMS sensors offer better resolution than conventional methods\, the inertia of the floating element limits their temporal response. Miniaturizing the sensing element of the thermal anemometry probe is a viable solution to obtain high-resolution measurements. This approach has been successfully demonstrated with velocity measurements in turbulent flows with ultra-miniature hot-wire probes\, which are able to fully resolve the turbulence spectrum even at high Reynolds numbers.\n\nMotivated by the success of ultra-miniature hot-wire probes in velocity measurements\, the present effort is directed at the development\, fabrication\, and demonstration of an ultra-miniature sensor\, based on the principles of thermal anemometry\, for wall-shear-stress measurements. The sensor design essentially consists of platinum filaments deposited on a thermally oxidized silicon substrate with electrical contact pads. The fabrication is carried out by oxide growth on a clean silicon wafer\, followed by two-layer electron beam lithography\, metal deposition\, and lift-off processes. Titanium is used for adhesion in the first layer\, followed by platinum deposition for the sensing element in the second layer. Dry reactive ion etching is used\, when needed\, to suspend the sensing element. Basic voltage-current characterization of the sensor is carried out prior to packaging of the sensors for use.\n\nA demonstration of the sensor is made in a turbulent boundary layer flow. The packaged sensor is integrated onto a flat plate in a low-speed wind tunnel facility\, and wall-shear-stress measurements are made in the turbulent boundary layer flow over the flat plate in the momentum thickness Reynolds number range of 1500 to 2500. The sensor is calibrated in the boundary layer flow in an in-situ manner by estimating the mean wall-shear-stress through hot-wire measurements of the flow velocity profile at different freestream velocities. The sensor fully resolves the spectrum of turbulent fluctuations in wall shear stress. The probability density distributions of wall-shear-stress fluctuations are found to match well with data reported in the literature\, thereby validating the sensor’s performance. Overall\, this work demonstrates the viability of making high-fidelity wall-shear-stress measurements using ultra-miniature thermal anemometry sensors. It lays the foundation for the development of a practical sensing tool for application outside the laboratory\, in a real-world environment.\n\nSpeaker : Keshanjali Gaur\n\nResearch Supervisor : Prof. Duvvuri Subrahmanyam
URL:https://aero.iisc.ac.in/event/ph-d-engg-development-of-an-ultra-miniature-wall-shear-stress-sensor/
CATEGORIES:Thesis Colloquium / Defence
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2026/01/Keshanja.jpg
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BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20260119T150000
DTEND;TZID=Asia/Kolkata:20260119T170000
DTSTAMP:20260516T024150
CREATED:20260116T043058Z
LAST-MODIFIED:20260119T103611Z
UID:10000112-1768834800-1768842000@aero.iisc.ac.in
SUMMARY:Ph.D. (Engg) :  Turbulence Energy Cascade in Physical  Space in a Turbulent Channel Flow
DESCRIPTION: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.\nThe mean energy and enstrophy cascades are shown to be predominantly local for all the Reynolds numbers. Away from the wall\, the degree of locality decreases while a broader range of scales participate in the cascade. Interestingly the distance at which the inter-scale flux peaks shows a distance-from-wall scaling\, implying relevance of the attached-eddy formalism to energy cascade in scale space (in addition to its relation ​ to momentum transport in physical space). Vorticity stretching as the underlying mechanism of cascade is studied through vorticity alignment statistics. The vortices show preferential alignment with intermediate eigenvector for smaller scale ratios and closer to the wall\, while alignment with the most extensional eigenvector is observed at larger scale ratios and away from the wall. The preferential alignment shows a complex dependence on the wall-normal distance\, suggesting that the wall has important influence on both energy transfer rates and the geometry of structures. Notwithstanding this\, the contribution from most extensional eigenvector dominates enstrophy generation for all conditions. The scaling of energy flux with scale size\, scale ratio\, wall-normal distance\, and Reynolds number is obtained using dimensional arguments and is validated against numerical results.  As the cascade progresses\, the energy at small scales gets concentrated in a small region of space\, reflected as intermittency in enstrophy and energy fluxes. The skewness and kurtosis increase at smaller length scales but they show weak increase with the Reynolds number. The morphology of energy flux and enstrophy iso-surfaces are characterized through Minkowski functionals. Enstrophy structures at small scales are like flattened long tubes\, while large-scale structures are blob-like or short-tube-like. The large-scale structures generally exhibit lower values of filamentarity. Energy flux structures show a similar behaviour\, with near-wall structures being more flattened compared to those farther from the wall. These findings remain unaffected by an increase in threshold for getting the iso-surfaces.\nOverall\, the present study provides new insights into the locality\, scaling\, and morphology of the energy and enstrophy cascade in the channel flow\, offering a unified framework for interpreting multi-scale turbulence dynamics in wall-bounded flows.\n\nSpeaker :  Aditya Anand\n\nResearch Supervisor :  Sourabh Suhas Diwan
URL:https://aero.iisc.ac.in/event/ph-d-engg-turbulence-energy-cascade-in-physical-space-in-a-turbulent-channel-flow/
LOCATION:STC Seminar Hall\, Dept. of Aerospace Engineering
CATEGORIES:Thesis Colloquium / Defence
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2026/01/Aditya123.jpg
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