A5045258450- Fluid Dynamics and Turbulent Flows
- Meteorological Phenomena and Simulations
- Atmospheric aerosols and clouds
- Wind and Air Flow Studies
- Aerodynamics and Acoustics in Jet Flows
- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Biomimetic flight and propulsion mechanisms
- Rheology and Fluid Dynamics Studies
- Fluid Dynamics and Vibration Analysis
- Fluid Dynamics and Heat Transfer
- Atmospheric chemistry and aerosols
- Solar Radiation and Photovoltaics
- Advanced Thermodynamics and Statistical Mechanics
- Heat Transfer Mechanisms
- Astrophysics and Star Formation Studies
- Electrohydrodynamics and Fluid Dynamics
- Aerospace Engineering and Energy Systems
- Combustion and flame dynamics
- Thermal Radiation and Cooling Technologies
- Air Traffic Management and Optimization
- Adaptive optics and wavefront sensing
- Aerospace and Aviation Technology
- Fluid Dynamics and Thin Films
- Solar and Space Plasma Dynamics
Jawaharlal Nehru Centre for Advanced Scientific Research
2010-2025
Ariel University
2022-2024
The University of Sydney
2024
Indian Institute of Science Bangalore
1993-2008
University of Delaware
2003
Context. Asteroseismic modelling of isolated stars presents significant challenges due to the difficulty in accurately determining stellar parameters, particularly age. These can be overcome by observing open clusters whose coeval members share an initial chemical composition. The light curves from all-sky survey Transiting Exoplanet Survey Satellite (TESS) allow us investigate and analyse variations with unprecedented level detail for first time. Aims. We aim detect gravity-mode...
Context . Magnetic activity is currently the primary limiting factor in radial velocity (RV) exoplanet searches. Even inactive stars, such as Sun, exhibit RV jitter of order a few m s −1 due to active regions on their surfaces. Time series chromospheric indicators, Ca II H&K lines, can be utilized reduce impact phenomena search programmes. In addition, identification and correction instrumental effects improve precision surveys. Aims We aim update HARPS -RVB ANK database include an...
The importance of numax (the frequency maximum oscillation power) for asteroseismology has been demonstrated widely in the previous decade, especially red giants. With large amount photometric data from CoRoT, Kepler and TESS, several automated algorithms to retrieve values have introduced. Most these correct granulation background power spectrum by fitting a model subtracting it before measuring numax. We developed method that does not require background. Instead, we simply divide function...
Abstract The evening transition is crucial in various phenomena, including boundary‐layer stability, temperature inversion, radiation fog, vertical mixing, and pollution dispersion. We have explored this using data from 80 days of observations across two fog seasons at the Kempegowda International Airport, Bengaluru (KIAB). Through field experiments simulations integrating aerosol interaction a radiation–conduction model, we elucidate impact aerosols on longwave cooling atmospheric boundary...
Stellar oscillations and granulation in red giants are both powered by convection. Studying the wavelength dependence of their amplitudes can provide useful insights on driving mechanism. It is also important for plans to carry out asteroseismology with Nancy Grace Roman Space Telescope, which will operate near infrared, check observational wavelength. In this work, we aim understand how oscillation power depend study existing predictions compare observations. We measure mean 279 Kepler...
Evening Transition (ET) over Kempegowda International Airport (77.70◦ E, 13.20◦ N) is investigated 2seasons to calculate robust statistics of decay Turbulent Kinetic Energy (TKE) in the Atmospheric BoundaryLayer (ABL). Although previous research on TKE during ET has largely relied Large Eddy Simulations(LES) and analytical models determine rates volume-averaged TKE, our study takes a more granularapproach.We use two remote sensing instruments (Radiometer Physics HATPRO...
Recent experimental results of Bhat and Narasimha (1996) have revealed a dramatic difference in the entrainment between jets plumes subjected to off-source volumetric heating their unheated counterparts. Experimental observations show that entrain more rapidly than jets; greater by plume is typically attributed presence buoyancy plume. In contrast, addition away from source produces opposite effect reduced entrainment. Apart buoyancy, other factors such as acceleration due pressure gradients...
Clouds are the largest source of uncertainty in climate science, and remain a weak link modeling tropical circulation. A major challenge is to establish connections between particulate microphysics macroscale turbulent dynamics cumulus clouds. Here we address issue from latter standpoint. First show how create bench-scale flows that reproduce variety cumulus-cloud forms (including two genera three species), track complete cloud life cycles--e.g., "cauliflower" congestus dissipating fractus....
One of the main scientific goals TESS mission is discovery transiting small planets around closest and brightest stars in sky. Here, using data from CARMENES, MAROON-X, HIRES spectrographs together with TESS, we report mass determination aplanetary system M1.5 V star GJ 806 (TOI-4481). a bright ( ≈ 10.8mag, J 7.3 mag) nearby d = 12 pc) M dwarf that hosts at least two planets. The innermost planet, b, has an ultra-short orbital period 0.93 d, radius 1.331 ± 0.023 R ⊕ , 1.90 0.17 mean density...
Abstract A common injector geometry upstream of a static mixer is the centerline injector. flow instability can arise due to viscosity differences between injected core‐flow and outer co‐flow. This adversely affect effectiveness mixing operation. An experimental investigation miscible viscosity‐stratified in circular was performed using Laser Induced Fluorescence (LIF) Particle Image Velocimetry (PIV). The results for stable region agree with analytical results. unstable exhibits different...
Double-diffusive finger convection occurs in many natural processes. The theories for double-diffusive phenomena that exist at present consider systems with linear stratification temperature and salinity. step change salinity are, however, not amenable to simple stability analysis. Hence factors control the width of finger, velocity, fluxes have been understood so far. In this paper we provide new physical insight regarding influence two-layer system through two-dimensional numerical...
A vertical jet of water impinging on a horizontal surface produces radial film flow followed by circular hydraulic jump. We report phenomenon where fairly large (1 ml) drops liquid levitate just upstream the jump thin air layer between drop and flow. explain using lubrication theory. Bearing action both in seems to be necessary support drops. Horizontal is given variety shapes observed depending volume properties. show that interaction forces due gravity, tension, viscosity inertia these...
This study examined the evolution of columnar-basalt structures using simple laboratory experiments and numerical simulation in double-diffusive finger system. Effect various parameters like Prandtl Rayleigh numbers has been considered study. Columnar-basalts are geological formations observed some ponded basalt-lava found at many parts world. They prismatic rock joints having polygonal cross-section with straight edges parallel faces. The typical cross-sectional dimensions vary from few...
Cumulus clouds, which are among the largest sources of uncertainty in climate change science and tropical circulation, have to-date resisted numerous attempts made during last six decades to unravel their cloud-scale dynamics. One major reason has been lack a convincing fluid-dynamical model difficulty making repeatable measurements an inherently transient flow. This article summarizes recent work showing that cumulus-type f lows can be generated laboratory by releasing volumetric heat into...
Abstract Heat transfer processes in the nocturnal boundary layer (NBL) influence surface energy budget and play an important role many micrometeorological processes, including formation of inversion layers, radiation‐fog control air‐quality near ground. Under calm clear‐sky conditions, radiation plays determining characteristics NBL. In this article, we report observations, close to ground, hypercooling that has a radiative origin, which leads anomalous vertical temperature profiles with...
Abstract Broadband flux emissivity schemes are often used to model infrared radiative exchanges in the atmosphere. In particular, such help highlight interaction of radiation with other transport processes, an aspect that is crucial understanding phenomena relevant nocturnal boundary layer (NBL). Although original were restricted radiatively black bounding surfaces, extension same nonblack surfaces has since been frequently NBL modeling. Herein, it shown erroneous and leads a spurious yet...
Characterizing the interaction between turbulence and radiative processes is necessary for understanding nocturnal atmospheric boundary layer. The subtle nature of exemplified in a phenomenon called 'Ramdas paradox' or 'lifted temperature minimum' (LTM), involving preferential cooling near Earth's surface. prevailing explanation LTM (the VSN model, Vasudeva Murthy et al (1993 Phil. Trans. R. Soc. A 344 183–206)) invokes exchange homogeneous atmosphere to predict large near-surface air...
Earlier studies on the circular hydraulic jump have shown that radial position of depends flow rate, gravity, and fluid viscosity. In this study, results from numerical simulations experiments jumps are presented through analysis, it is momentum flux an additional controlling parameter in determining location. Apart location, variation film thickness with parameters also obtained simulations. By including dependence dissipation along other parameters, data radius simulation (including...
Aims. We use the recently published database (Trifonov et al. 2020) of radial velocities (RVs) that were derived from fifteen years HARPS/ESO observations to search for planet candidates. Methods. For targets with sufficient RV data, we apply an automated algorithm identify significant periodic signals and fit a Keplerian model orbital estimates. also auxiliary data stellar-activity indices compare our findings existing literature, detect have no counterpart in activity timeseries. The most...