Person:
Ray, Arnab Kumar

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Arnab Kumar Ray

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Faculty

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079-68261612

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Specialization

Astrophysical Accretion, Fluid Dynamics, Nonlinear Systems

Abstract

Biography

I hold a doctorate in astrophysical fluid dynamics. My research methods are theoretical in nature, with my present research interests being astrophysical accretion, fluid dynamics and nonlinear systems. I have publications in peer-reviewed journals of astrophysics, gravitation, nonlinear dynamics, condensed matter physics, nuclear physics, complex systems and geophysics. I also have research experience in the seismic processing industry. I have interest in designing curriculum and exploring new pedagogic approaches to aid the teaching-learning process.

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2018 - 201912020 - 20234

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Now showing 1 - 5 of 5
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    Surface tension and instability in the hydrodynamic white hole of a circular hydraulic jump
    (ResearchGate, 10-01-2021) Bhattacharjee, Jayanta K; Ray, Arnab Kumar; DA-IICT, Gandhinagar
    We impose a linearized Eulerian perturbation on a steady, shallow, radial outflow of a liquid (water), whose local pressure function includes both the hydrostatic and the Laplace pressure terms. The resulting wave equation bears the form of a hydrodynamic metric. A dispersion relation, extracted from the wave equation, gives an instability due to surface tension and the cylindrical flow symmetry. Using the dispersion relation, we also derive three known relations that scale the radius of the circular hydraulic jump in the outflow. The first two relations are scaled by viscosity and gravity, with a capillarity-dependent crossover to the third relation, which is scaled by viscosity and surface tension. The perturbation as a high-frequency traveling wave, propagating radially inward against the bulk outflow, is blocked just outside the circular hydraulic jump. The amplitude of the wave also diverges here because of a singularity. The blocking is associated with surface tension, which renders the circular hydraulic jump a hydrodynamic white hole.
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    Regularities in stock markets
    (World Scientific, 26-08-2020) Kakkad, Abhin; Vasoya, Harsh; Ray, Arnab Kumar; DA-IICT, Gandhinagar; Kakkad, Abhin (201501419); Vasoya, Harsh (201501405)
    From the stock markets of six countries with high GDP, we study the stock indices,�S&P 500 (NYSE, USA),�SSE Composite (SSE, China),�Nikkei (TSE, Japan),�DAX (FSE, Germany),�FTSE 100 (LSE, Britain)�and�NIFTY (NSE, India). The daily mean growth of the stock values is exponential. The daily price fluctuations about the mean growth are Gaussian, but with a nonzero asymptotic convergence. The growth of the monthly average of stock values is statistically self-similar to their daily growth. The monthly fluctuations of the price follow a Wiener process, with a decline of the volatility. The mean growth of the daily volume of trade is exponential. These observations are globally applicable and underline regularities across global stock markets.
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    A theoretical prediction of rotating waves in Type-I hydraulic jumps
    (Elsevier, 30-11-2018) Ray, Arnab Kumar; Sarkar, Niladri; Basu, Abhik; KBhattacharjee, Jayanta; DA-IICT, Gandhinagar
    The rotation of polygons in a Type-II hydraulic jump prompts us to look for a rotational feature in the Type-I hydraulic jump. Coupling the radial and azimuthal flows breaks the azimuthal symmetry of the shallow-water circular jump. An unstable rotating wave along the circumference of the jump is possible with a�kinematic viscosity�of very small order, whose upper threshold value is less than the�kinematic viscosity�of water.
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    Global dynamics of GDP and trade
    (World Scientific, 01-02-2023) Kakkad, Abhin; Ray, Arnab Kumar; DA-IICT, Gandhinagar
    We use the logistic equation to model the dynamics of the GDP and the trade of the six countries with the highest GDP in the world, namely, USA, China, Japan, Germany, UK and India. From the modelling of the economic data, which are made available by the World Bank, we predict the maximum values of the growth of GDP and trade, as well as the duration over which exponential growth can be sustained. We set up the correlated growth of GDP and trade as the phase solutions of an autonomous second-order dynamical system. GDP and trade are related to each other by a power law, whose exponent seems to differentiate the six national economies into two types. Under conducive conditions for economic growth, our conclusions have general validity.
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    Dissipation and acoustic tunnelling about the sonic horizon of Bondi accretion
    (Wiley, 25-11-2020) Ray, Arnab Kumar; DA-IICT, Gandhinagar
    Binary pulsars can be excellent probes of ultra-light dark matter. We consider the scenario where the latter is represented by a spin-2 field. The coherent oscillations of the dark matter field perturb the dynamics of binary systems, leading to secular effects for masses that resonate with the binary systems. For the range 10?23�eV ?�m�?�10?17�eV we show that current timing data could potentially constrain the universal coupling strength of dark matter to ordinary matter at the level of ?�?�10?5.