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TZID:Asia/Kolkata
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TZOFFSETFROM:+0530
TZOFFSETTO:+0530
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DTSTART:20260101T000000
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DTSTART;TZID=Asia/Kolkata:20261006T143000
DTEND;TZID=Asia/Kolkata:20261006T170000
DTSTAMP:20261013T195044
CREATED:20261005T050831Z
LAST-MODIFIED:20261005T101944Z
UID:10000155-1791297000-1791306000@aero.iisc.ac.in
SUMMARY:M.Tech (Res): Direct Numerical Simulation of Turbulent Aerosol Transport in Human Respiratory Flows
DESCRIPTION:Airborne transmission of respiratory diseases is governed by the coupled dynamics of the exhaled turbulent flow and the transport of pathogen-laden aerosols and droplets. This thesis studies two representative respiratory activities\, speech and cough\, and quantifies the infection probability using Direct Numerical Simulations. The incompressible Boussinesq Navier-Stokes equations are solved using Megha-5 solver\, including the required scalar and dispersed-phase transport equations. Speech flow is studied for a repeated plosive-rich utterance at soft\, normal and loud levels. Aerosol exposure is quantified from the instantaneous and time-integrated flux through a face-sized region representing a silent listener at different streamwise separations. Normal and loud speech develop from individual puffs into a jet-like mean flow\, whereas soft speech remains comparatively underdeveloped. The centreline exposure increases in the approximate ratio 1:5.4:18.4\, governed mainly by the source conditions. At a separation of 1 m\, the infection probabilities are approximately 12%\, 28% and 63% for soft\, normal and loud speech\, respectively. For cough flow\, the existing variable-timescale model is compared with a variable-number-density closure based on the Direct Quadrature Method of Moments. The latter transports droplet number density and total surface area as Eulerian fields and captures strong spatial non-uniformity\, particularly within the toroidal vortex at the puff head. It increases the centreline infection probability by 10-30%\, while a laterally displaced breathing zone produces a non-monotonic variation with distance. The results show that infection risk cannot be described by separation distance alone. The framework provides distance-resolved inputs for room-scale and epidemiological transmission models. \n  \nSpeaker : SUBBA REDDY GARI SHASHANK REDDY \nResearch Supervisor : Sourabh Suhas Diwan
URL:https://aero.iisc.ac.in/event/m-tech-res-direct-numerical-simulation-of-turbulent-aerosol-transport-in-human-respiratory-flows/
LOCATION:AE Conference Room \, AE 003
CATEGORIES:Thesis Colloquium / Defence
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2026/10/SUBBA.jpg
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DTSTART;TZID=Asia/Kolkata:20260807T110000
DTEND;TZID=Asia/Kolkata:20260807T130000
DTSTAMP:20261013T195044
CREATED:20260804T053733Z
LAST-MODIFIED:20260811T060311Z
UID:10000144-1786100400-1786107600@aero.iisc.ac.in
SUMMARY:Ph.D. (Engg): Aerodynamics and Stability of a Generic Tailless UAV in Ground Effect
DESCRIPTION:Tailless UAVs are stealthy\, high-subsonic configurations used for deep penetration into contested airspace. These configurations have wing with moderate leading edge sweep angle with no definite fuselage and lack both horizontal tail and vertical tail which makes the aerodynamics of these configurations very unique. The increase in autonomous UAVs in recent times have led to renewed interest in this class of configurations. Autonomous take-off and landing of tailless UAVs are complex technologies that require a detailed understanding of the underlying aerodynamic flow physics. The current literature on the ground effects focusses mainly on conventional configuration or high swept delta wings.  This work focusses on understanding the aerodynamic behavior of a typical tailless UAV near the ground and its influence on the stability characteristics. RANS CFD analysis is carried out at different ground heights\, angle of attack and side slip angle. Studies are also carried to understand the effect of roll orientation effect on the ground effects. The  effect of ground on the elevon behavior near the ground are also brought out. Unsteady CFD Analysis are conducted for different sink rates and pitch angles and compared with Static Ground Effects.\n The lift coefficient under Steady Ground Effects was observed to decrease near the ground at lower angle of attack and increase at high angle of attack. The region between the ground and aircraft acts like a venturi at low angle of attack. At high angle of attack\, ramming effect is observed due to increase in the pressure on the bottom surface. The drag coefficient does not change at lower angle of attack whereas significant reduction is observed at higher angle of attack due to the reduction in the induced drag.  The UAV shows a reduction in directional stability near the ground. The rolling moment due to side slip angle shows a stable behavior near the ground.  The roll orientation of the UAVs impacts the rolling moment behavior near the ground providing increased rolling moment near the ground which has a tendency to counter the direction of the roll.  Unsteady CFD Analysis is conducted for different sink rates and pitch angles and compared with Static Ground Effects which shows significant change especially at lower pitch angles. \n The aerodynamic changes introduced by the  presence of ground impacts the Stability of the UAV significantly.  The Stability  changes are particularly important for the tailless UAV as it is neutrally stable in the longitudinal and directional plane. A increase in Static Margin of 0.5% is observed at the lowest ground  height  (h/b = 0.15). There is also marginal increase in weather cock stability (Cnβ)  and roll stability (Clβ) at high angle of attack near the ground. The dynamics of the tailless UAV near the ground has interesting behavior near the ground. The short period mode has stabilizing behavior near the ground whereas the Dutch roll tends to be slightly unstable near the ground. The roll orientation of the UAV seems to impact the Dutch roll mode changing from slightly unstable to a slightly stable behavior.  The aerodynamics and stability aspects are highly coupled for tailless UAV. The understanding of tailless UAV near the ground will be key for development of control schemes for robust take-off and landing of these Configurations. \n  \nSpeaker :  B Saravanan \nResearch Supervisor :  N Balakrishnan \n 
URL:https://aero.iisc.ac.in/event/aerodynamics-and-stability-of-a-generic-tailless-uav-in-ground-effect/
LOCATION:AE Conference Room \, AE 003
CATEGORIES:Thesis Colloquium / Defence
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2026/08/Saravanan.jpg
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