Browsing by Author "L.P. Singh"

Now showing 1 - 13 of 13

Analytical solution of converging shock wave in magnetogasdynamics
(2010) L.P. Singh; M. Singh; Bishun D. Pandey
In this paper, a similarity solution to a problem in magnetogasdynamics with strong converging cylindrical shock wave is examined. An analytical description of converging shock waves is presented by replacing the previous approach for numerical solutions of the ordinary differential equations with a theoretical study of the singular points of the differential equations. A study of singular points of the system of differential equations leads to an analytic description of the flowfield and a determination of the similarity exponent. The influences of adiabatic heat exponent and magnetic field strength on the flow pattern for various cases are assessed. The general behavior of the velocity and density distribution remains unaffected. However, the pressure profiles are greatly affected by the magnetic field interaction. Copyright ©2010 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.
Evolution of weak discontinuity waves in non-ideal interstellar environments
(Springer, 2023) Shweta; Rahul Kumar Chaturvedi; Shobhit Kumar Srivastava; L.P. Singh
A systematic method is used to study the problem of propagation of planar, cylindrically symmetric and spherically symmetric shock waves of the one-dimensional motion of an inviscid, self-gravitating, non-ideal interstellar gas cloud. The analytic solution of the problem is resolved, which specifies non-linear behavior in the physical plane. The transport equation, which describes the evolution of weak discontinuity in non-ideal gas is derived. It is observed that the nature of the solution completely depends on the net volumetric cooling rate and self-gravitating parameter. It is observed that an increase in the value of self-gravitating parameter results in delay of process of shock formation and shock forms early when heating dominates cooling in the system. Also, expansive waves take less time to decay in planar geometry as compared to cylindrical and spherical geometries and compressive waves take more time to develop shocks for cylindrical and spherical geometries as compared to planar geometry. © 2023, Indian Academy of Sciences.
New lifetime measurement for the 21+ level in Sn 112 by the Doppler-shift attenuation method
(American Physical Society, 2021) A. Kundu; Md.S.R. Laskar; R. Palit; R. Raut; S. Santra; N. Shimizu; T. Togashi; E. Ideguchi; H. Pai; S. Ali; F.S. Babra; R. Banik; Soumik Bhattacharya; S. Biswas; Biswajit Das; P. Dey; R. Donthi; A. Goswami; S. Jadhav; G. Mukherjee; B.S. Naidu; S. Rajbanshi; L.P. Singh; H.P. Sharma; S.S. Tiwary; A.T. Vazhappilly
Levels in the Sn112 nucleus have been excited by inelastic scattering with Cl35 projectile at Elab=195MeV. The Doppler affected ?-ray peak arising from the decay of the 21+ level has been analyzed, using updated methodologies, to extract the level lifetime and corresponding electric quadrupole (E2) transition probability, B(E2;0g.s.+?21+). The present result is discrepant with respect to the results reported from existing lifetime measurements, but in compliance with independent systematic measurements of the low-lying E2 transition strengths in the stable even-mass Sn isotopes, by pure Coulomb excitation as well as heavy-ion induced inelastic collisions. The transition probability also confirms an enhancement in collectivity for the 21+ level, and is found to be in good agreement with generalized seniority model (GSM) as well as state-of-the-art Monte Carlo shell model (MCSM) calculations. Within the realm of the MCSM scheme, the enhancement is understood in terms of oblate deformations for both the 0g.s.+ and 21+ states in Sn112 arising due to strong proton-core excitations and enhanced proton-neutron interactions. In addition, limits for the lifetime of the 31- level and the E1 transition probability, B(E1;31-?21+), have been obtained. ©2021 American Physical Society.
On the evolution of magnetic shock wave in the mixture of gas and small solid dust particles
(Elsevier B.V., 2022) Pooja Gupta; L.P. Singh
The paper aims to analyze the evolutionary behavior of weakly nonlinear waves propagating in one-dimensional unsteady flow of perfectly conducting compressible fluid subjected to a transverse magnetic field with dust particles. The method of progressive wave approach is utilized to determine the evolution equation characterizing the propagation of wave and also obtained the condition for first wave breaking at finite time. Further, we analyze the behavior of acceleration wave propagating in the medium considered. Also, the propagation of disturbances in the form of sawtooth wave (half N-wave) is studied here. It is observed that the presence of mass fraction of solid particles (kp) and β both causes to slow down the decay process. Also, the effect of axial magnetic field is to increase the growth rate of sawtooth wave (Half N-wave) as compared to in the absence of axial magnetic field. Further, the effect of magnetic field is to slow down the decay process in the presence of mass fraction of solid particles (kp). © 2022 The Physical Society of the Republic of China (Taiwan)
Propagation of nonlinear wave in 2-D planar and axisymmetric non-ideal radiating gas flow under the influence of magnetic field
(Springer, 2024) Shobhit Kumar Srivastava; Rahul Kumar Chaturvedi; L.P. Singh
Influence of magnetic field on the propagation of shock waves in radiation gasdynamics is analysed by using wavefront analysis method. We examined behavior of the waves propagated into the two-dimensional (2-D) steady supersonic magnetogasdynamic flow of non-ideal gas with radiation. The transport equations are derived, which determine the condition for the shock formation. The effect of non-idealness and thermal radiation and their consequences under the influence of magnetic field is studied and examined how the flow patterns of the disturbance vary with respect to the variation in the parameters of the flow. It is found that the presence of a magnetic field plays an essential role in the wave propagation phenomena. Nature of the solution with respect to Mach number is analysed, and it is examined how the shock formation distance changes with an increase or decrease in the value of Mach number. Also, the effect of non-idealness on the shock formation distance is elucidated and examined how the shock formation affects the increase in the value of non-ideal parameter in the presence of magnetic field with thermal radiation. © 2023, Indian Academy of Sciences.
Shock wave solution for the planar, cylindrically, and spherically symmetric flows of non-ideal relaxing gas
(Elsevier B.V., 2022) Shweta; Rahul Kumar Chaturvedi; L.P. Singh
In the present article, we investigate one-dimensional non-ideal relaxing gas to study solution of shocks for planar and non-planar flows, more specifically cylindrically symmetric, and spherically symmetric flows. The analytic solution of the problem is determined in the characteristic plane. It signifies that linear solution in this plane reveals non-linear behavior in the physical plane. Also, the condition of shock formation has been determined by analyzing the growth and deterioration of shocks using transport equations. It is observed that nature of the solution completely depends upon relaxing gas parameters and non-idealness. All computations are done using computational package MATHEMATICA. © 2022 The Physical Society of the Republic of China (Taiwan)
The application of differential constraint method for the solution of non-homogeneous generalized Riemann problem
(Institute of Physics, 2023) Gaurav; L.P. Singh; Pradeep
This paper reports the solution to the Non-homogeneous Riemann problem by applying the approach of differential constraint for the one-dimensional (1 − D) generalized Chaplygin gas equations with non-constant initial data. Here we take source term as a Coulomb type constant frictional term. We reduced the governing non-homogeneous model into a homogeneous one by introducing a new velocity variable. By virtue of this advantage of frictional type source term, we would easily determine the solution of reformulated homogeneous governing model. We have computed the differential constraint and its consistency conditions for the specified model. Moreover, we have derived here the compatibility condition between the governing model and the differential constraints. The solutions to generalized Riemann problem for the 1 − D Euler’s equation of governing gas model are obtained as well as for the smooth and non-constant initial conditions the comprehensive overview of the solutions is studied. © 2023 IOP Publishing Ltd.
The concentration and cavitation in the Riemann solution for non-homogeneous logrithmic equation of state with magnetic field
(American Institute of Physics Inc., 2024) Pradeep; Rahul Kumar Chaturvedi; L.P. Singh
In the present study, the phenomena of concentration and cavitation in the Riemann solution for the non-homogeneous hyperbolic system with logarithmic equation of state and magnetic field is analyzed. Firstly, we introduced new state variable for the velocity to modify the non-conservative system into conservative system and solved the Riemann problem for modified system constructively. Further, the Riemann solutions for the transport equations is investigated as pressure and magnetic field vanish. It is proved that the Riemann solution for the non-homogeneous hyperbolic system with logarithmic equation of state and magnetic field having two shock waves converges to the delta shock wave solution of the transport equations as pressure and magnetic field vanish. It is also proved that the Riemann solution for the non-homogeneous hyperbolic system with logarithmic equation of state and magnetic field having two rarefaction waves converges to the contact discontinuity solution of the transport equations as pressure and magnetic field vanish. © 2024 Author(s).
The effect of dust particles on the evolution of planar and non-planar shock wave in two-dimensional supersonic flow of van der Waals gas
(Springer Science and Business Media Deutschland GmbH, 2022) Pradeep; Rahul Kumar Chaturvedi; L.P. Singh
The motive of this study is to investigate the impact of the dust particles on the shock formation in two-dimensional steady supersonic flow of the composition of van der Waals gas and small solid dust particles for the planar, cylindrically symmetric and spherically symmetric cases. It is shown that the governing equations describing the van der Waals gas with dust particles is hyperbolic in nature. Further, by employing the method of wavefront analysis, we derived the transport equations for shock wave which lead to derivation of shock formation distance and also, provide the relations of shock formation. Also, it is determined as how the shock formation distance is affected by the presence of dust particles, parameter of van der Waals gas and upstream flow Mach number (M> 1) by using MATHEMATICA 11 software. © 2022, The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature.
The formation of shock wave in a two-dimensional supersonic planar and axisymmetric non-ideal gas flow with magnetic field
(Springer Science and Business Media Deutschland GmbH, 2021) Rahul Kumar Chaturvedi; Pradeep; L.P. Singh
This paper presents an analysis of the of the shock formation in 2-D steady supersonic flow of non-ideal gas with magnetic field for the planar flow and axisymmetric flows. It is shown that the governing equations describing the non-ideal gas flow with magnetic field is hyperbolic in nature. Further, using the theory of the propagation of wavefronts defined by weak shock, we derived the transport equations for shock wave which lead to determination of shock formation distance and provide the conditions of shock formation. The formation of shock wave is affected by the presence of magnetic field, non-ideal parameter and upstream flow Mach number M> 1 is shown. © 2021, The Author(s) under exclusive licence to Sociedade Brasileira de Matemática Aplicada e Computacional.
The growth and decay of nonlinear wave in polytropic reacting gas with small solid dust particles
(Elsevier B.V., 2024) Rahul Kumar Chaturvedi; Shobhit Kumar Srivastava; L.P. Singh; Nilam Venkata Koteswararao; Akshara Makrariya
The aim of this study is to examine the evolutionary process of shock waves along the characteristic path under the effect of dust particles in a polytropic reacting gas. Testing the nature of the governing quasilinear of this system as a coordinate, we reconstruct the governing equations as Bernoulli's differential equation and obtain the results. The results in the characteristic plane can display a non-linear behavior in the physical plane. It is shown how the reacting gas parameter influences the evolutionary process of the compressive and expansive waves, respectively, in reacting gas flows. Also, it is shown how the existence of dust in reacting gas influences the growth and decay of the compressive and expansive waves. The transport equation leading to the evolution of shock waves is determined and used to derive the condition for the shock formation. The comparative study of the effect of reacting gas parameters and dust particles on the flow patterning and distorting of shock waves for planar, cylindrically and spherically symmetric flows is also performed. © 2023 The Physical Society of the Republic of China (Taiwan)
The Riemann problem for one-dimensional dusty gas dynamics with external forces
(Taylor and Francis Ltd., 2022) Shobhit Kumar Srivastava; Rahul Kumar Chaturvedi; L.P. Singh
This article concerns the study of the Riemann Problem (RP) for a non-homogeneous system governing the one-dimensional compressible flow of dusty gas, where the external forces are assumed to be continuous function of time. The elementary wave solutions such as rarefaction wave, shock wave, and contact discontinuity are rigorously determined. The effect of dust particles on the density and flow velocity and shock speed is examined, and their consequences on the solution of the Riemann Problem are discussed. Moreover, we discussed the condition for the existence of vacuum appears in the solution of the Riemann Problem. © 2022 Informa UK Limited, trading as Taylor & Francis Group.
Wave propagation in a steady supersonic flow of a radiating gas past plane and axisymmetric bodies
(Springer-Verlag, 1988) L.P. Singh; V.D. Sharma; N. Gupta
Using the method of wavefront analysis the paper presents an analysis of shock wave formation in a two-dimensional steady supersonic flow of a radiating gas past plane and axisymmetric bodies such as a beak and sharp edged ring. Transport equations are derived which lead to the determination of the shock formation distance and also to conditions which insure that no shock will ever evolve on the wavefront. It is assessed as to how the shock formation distance is influenced by the presence of thermal radiation, the initial body curvature and upstream flow Mach number M0>1. © 1988 Springer-Verlag.