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Search Results: 1 - 10 of 2133 matches for " Rabindra Nath Mondal "
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Combined Effects of Centrifugal and Coriolis Instability of the Flow through a Rotating Curved Duct with Rectangular Cross Section  [PDF]
Rabindra Nath Mondal, Samir Chandra Ray, Shinichiro Yanase
Open Journal of Fluid Dynamics (OJFD) , 2014, DOI: 10.4236/ojfd.2014.41001
Abstract: Combined effects of centrifugal and coriolis instability of the flow through a rotating curved duct with rectangular cross section have been studied numerically by using a spectral method, and covering a wide range of the Taylor number  for a constant Dean number. The rotation of the duct about the center of curvature is imposed in the positive direction, and the effects of rotation (Coriolis force) on the flow characteristics are investigated. As a result, multiple branches of asymmetric steady solutions with two-, three-and multi-vortex solutions are obtained. To investigate the non-linear behavior of the unsteady solutions, time evolution calculations as well as power spectrum of the unsteady solutions are performed, and it is found that the unsteady flow undergoes through various flow instabilities in the scenario “chaotic → multi-periodic → periodic → steady-state”, if Tr is increased in the positive direction. The present results show the characteristics of both the secondary flow and axial flow distribution in the flow.
Radiation-Conduction Interaction of Steady Streamwise Surface Temperature Variations on Vertical Free Convection
Md. Kutub Uddin,Rabindra Nath Mondal
ISRN Applied Mathematics , 2011, DOI: 10.5402/2011/927416
Abstract:
A New Approach of Solving Linear Fractional Programming Problem (LFP) by Using Computer Algorithm  [PDF]
Sumon Kumar Saha, Md. Rezwan Hossain, Md. Kutub Uddin, Rabindra Nath Mondal
Open Journal of Optimization (OJOp) , 2015, DOI: 10.4236/ojop.2015.43010
Abstract: In this paper, we study a new approach for solving linear fractional programming problem (LFP) by converting it into a single Linear Programming (LP) Problem, which can be solved by using any type of linear fractional programming technique. In the objective function of an LFP, if β is negative, the available methods are failed to solve, while our proposed method is capable of solving such problems. In the present paper, we propose a new method and develop FORTRAN programs to solve the problem. The optimal LFP solution procedure is illustrated with numerical examples and also by a computer program. We also compare our method with other available methods for solving LFP problems. Our proposed method of linear fractional programming (LFP) problem is very simple and easy to understand and apply.
Time-Dependent Flow with Convective Heat Transfer through a Curved Square Duct with Large Pressure Gradient  [PDF]
Rabindra Nath Mondal, Md. Nurul Amin Helal, Poly Rani Shaha, Nayan Kumar Poddar
Open Journal of Fluid Dynamics (OJFD) , 2015, DOI: 10.4236/ojfd.2015.53026
Abstract: A numerical study is presented for the fully developed two-dimensional laminar flow of viscous incompressible fluid through a curved square duct for the constant curvature δ = 0.1. In this paper, a spectral-based computational algorithm is employed as the principal tool for the simulations, while a Chebyshev polynomial and collocation method as secondary tools. Numerical calculations are carried out over a wide range of the pressure gradient parameter, the Dean number, 100 ≤ Dn ≤ 3000 for the Grashof number, Gr, ranging from 100 to 2000. The outer wall of the duct is treated heated while the inner wall cooled, the top and bottom walls being adiabatic. The main concern of the present study is to find out the unsteady flow behavior i.e. whether the unsteady flow is steady-state, periodic, multi-periodic or chaotic, if Dn or Gr is increased. It is found that the unsteady flow is periodic for Dn = 1000 at Gr = 100 and 500 and at Dn = 2000, Gr = 2000 but steady-state otherwise. It is also found that for large values of Dn, for example Dn = 3000, the unsteady flow undergoes in the scenario “periodic→chaotic→periodic”, if Gr is increased. Typical contours of secondary flow patterns and temperature profiles are also obtained, and it is found that the unsteady flow consists of single-, two-, three- and four-vortex solutions. The present study also shows that there is a strong interaction between the heating-induced buoyancy force and the centrifugal force in a curved square passage that stimulates fluid mixing and consequently enhance heat transfer in the fluid.
Study Chromaticity of Solar Spectrum  [PDF]
Nagendra Nath Mondal
International Journal of Astronomy and Astrophysics (IJAA) , 2014, DOI: 10.4236/ijaa.2014.43047
Abstract: The chromaticity of solar spectrum is studied with the help of a Solar Spectrum Monitor system that can detect individual color in the spectrum. Recent observations done by the detector on the Solar Radiation and the Erath Milieu Experiment suggest that the sun’s visible spectral irradiance changes from May 2009 to September 2012. The data of Earth’s coordinates and environment have been taken since April 2005 after the devastating Tsunami (December, 2004) of India. The bizarre data of zenith angle, azimuth angle, and temperature of the Earth’s atmosphere show their changes of maxima and minima epoch to epoch. The data of solar spectrum monitor have been taking since 2009 and significant transformations of colored ratios ΔRB/W and ΔRR/W per hour are observed among the regions of each solstice between 2009 and 2012. The author advocates that the abrupt vagaries of the Earth’s movements may cause devastating tsunamis, earthquake, volcanic eruption, cyclones and tornadoes in addition of anomalous changes of solar spectral irradiation, humidity,
Discovered Solar Positronium  [PDF]
Nagendra Nath Mondal
International Journal of Astronomy and Astrophysics (IJAA) , 2014, DOI: 10.4236/ijaa.2014.44057
Abstract: I describe a method for the observation of Positronium (Ps) involvement in the solar radiation spectrum. In this method, Rydberg-Ritz’s principle and Planck’s radiation formula are used to acquire information of the atomic transitions of Ps alike Hydrogen and Helium. In order to perform this experiment, an advanced solar spectrum monitor is constructed by utilizing light emitting diodes (LED) of various colors. A detailed study on this method provides qualitative agreement with experimental data, giving insight to the physical process involved in the solar radiation spectrum and confirming the existence of solar Ps.
Discovery of Light-Light Scattering (A Test of the Primordial Universe)  [PDF]
Nagendra Nath Mondal
International Journal of Astronomy and Astrophysics (IJAA) , 2016, DOI: 10.4236/ijaa.2016.64031
Abstract: Different types of scatterings of photons with atoms, theoretical and experimental evidences of the light-light scattering in the visible range of electromagnetic waves are discussed. An inexpensive detection system of scattered light is developed in order to study this phenomenon without considering the scattering cross sections and photon structure function, and results infer that the universe is covered by the mesh of scattered photons. Asymmetry measurement of light-light scatterings shows that lower frequency photon scattered a lot than higher frequency photons. The homogeneity of mesh in absence of a direct incident light is better than that of presence although mesh intensity goes down and up respectively. The recent measurement of gravitational waves from black holes invokes this phenomenon that the primordial forms of the universe are the mesh of scattered light that intensity is extremely low in the absence of stars in a region where they sink is called a black hole.
Radiative Heat Transfer of an Optically Thick Gray Gas in The Presence of Indirect Natural Convection  [PDF]
Rabindra Nath Jana, Swapan Kumar Ghosh
World Journal of Mechanics (WJM) , 2011, DOI: 10.4236/wjm.2011.12009
Abstract: We study the effects of thermal radiation of a viscous incompressible fluid occupying a semi-infinite region of space bounded by an infinite horizontal moving hot flat plate in the presence of indirect natural convection by way of an induced pressure gradient. The fluid is a gray, absorbing emitting radiation but a non scattering medium. An exact solution is obtained by employing Laplace transform technique. Since temperature field depends on Reynold number the flow is considered to be non-isothermal case (the temperature of the plate Tw ≠ constant) and for an isothermal case (Tw = constant) the flow is determined by the Reynold number which is equal to 1.
Unsteady Couette Flow through a Porous Medium in a Rotating System  [PDF]
Maitree Jana, Sanatan Das, Rabindra Nath Jana
Open Journal of Fluid Dynamics (OJFD) , 2012, DOI: 10.4236/ojfd.2012.24016
Abstract: An investigation has been made on an unsteady Couette flow of a viscous incompressible fluid through a porous me- dium in a rotating system. The solution of the governing equations has been obtained by the use of Laplace transform technique. It is found that the primary velocity decreases and the magnitude of the secondary velocity increases with an increase in rotation parameter. The fluid velocity components are decelerated by an increase of Reynolds number. An increase in porosity parameter leads to increase the primary velocity and the magnitude of the secondary velocity. It is also found that the solution for small time converges more rapidly than the general solution. The asymptotic behavior of the solution is analyzed for small as well as large values of rotation parameter and Reynolds number. It is observed that a thin boundary layer is formed near the moving plate of the channel and the thicknesses of the boundary layer increases with an increase in porosity parameter.
Provenance Variability during Damuda Sedimentation in the Talchir Gondwana Basin, India – A Statistical Assessment  [PDF]
Rabindra Nath Hota, Bijay Kumar Das, Madhusmita Sahoo, Wataru Maejima
International Journal of Geosciences (IJG) , 2011, DOI: 10.4236/ijg.2011.22013
Abstract: The Talchir Gondwana basin houses the Talchir Formation at the base, succeeded by the Damuda Group and the Kamthi Formation in upward progression. The present study is an attempt to determine the provenance of the Damuda Group and its variability in terms of location, climate and tectonism through time from the composition of sandstone grains and detritus of the constituent Karharbari, Barakar and Barren Measures formations. The Damuda sandstones are composed of variable amounts of monocrystalline undulatory, nonundulatory and polycrystalline quartz grains, potash and plagioclase feldspars as well as metamorphic and sedimentary rock fragments in addition to heavy accessories. Palaeocurrent studies suggest that the Eastern Ghats Supergroup lying to the south of the basin served as the source area of the Damuda sediments. Plots of sandstone composition in tectonic setting discrimination diagrams suggest derivation of the detritus from craton interior, continental block and recycled orogen provinces. Statistical analyses indicate significant differences in the detrital modes of the sandstones of the Karharbari, Barakar and Barren Measures formations, which may be attributed to temporal and spatial variation of the provenance coupled with climate change in commensurate with Damuda sedimentation.
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