scholarly journals Four-Quadrant Riemann Problem for a 2×2 System II

Mathematics ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 592
Author(s):  
Jinah Hwang ◽  
Suyeon Shin ◽  
Myoungin Shin ◽  
Woonjae Hwang
Keyword(s):  
Initial Data ◽  
Riemann Problem ◽  
Numerical Solutions ◽  
Analytic Solutions ◽  
Wave Interactions ◽  
Delta Shock ◽  
Elementary Wave ◽  
Initial Discontinuity ◽  
The Rich ◽  
Four Quadrant

In previous work, we considered a four-quadrant Riemann problem for a 2×2 hyperbolic system in which delta shock appears at the initial discontinuity without assuming that each jump of the initial data projects exactly one plane elementary wave. In this paper, we consider the case that does not involve a delta shock at the initial discontinuity. We classified 18 topologically distinct solutions and constructed analytic and numerical solutions for each case. The constructed analytic solutions show the rich structure of wave interactions in the Riemann problem, which coincide with the computed numerical solutions.

scholarly journals Four-Quadrant Riemann Problem for a 2×2 System Involving Delta Shock

Mathematics ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 138
Author(s):  
Jinah Hwang ◽  
Suyeon Shin ◽  
Myoungin Shin ◽  
Woonjae Hwang
Keyword(s):  
Numerical Solution ◽  
Riemann Problem ◽  
Hyperbolic Conservation Laws ◽  
Analytic Solution ◽  
Hyperbolic Conservation ◽  
Delta Shock ◽  
Initial Discontinuity ◽  
Planar Wave ◽  
Four Quadrant ◽  
Elementary Waves

In this paper, a four-quadrant Riemann problem for a 2×2 system of hyperbolic conservation laws is considered in the case of delta shock appearing at the initial discontinuity. We also remove the restriction in that there is only one planar wave at each initial discontinuity. We include the existence of two elementary waves at each initial discontinuity and classify 14 topologically distinct solutions. For each case, we construct an analytic solution and compute the numerical solution.

scholarly journals The Perturbed Riemann Problem with Delta Shock for a Hyperbolic System

2018 ◽  
Vol 2018 ◽  
pp. 1-11
Author(s):  
Xinli Han ◽  
Lijun Pan
Keyword(s):  
Initial Data ◽  
Riemann Problem ◽  
Hyperbolic System ◽  
Contact Discontinuity ◽  
Riemann Problems ◽  
Delta Shock ◽  
Riemann Solution ◽  
Internal Mechanism

In this paper, we study the perturbed Riemann problem with delta shock for a hyperbolic system. The problem is different from the previous perturbed Riemann problems which have no delta shock. The solutions to the problem are obtained constructively. From the solutions, we see that a delta shock in the corresponding Riemann solution may turn into a shock and a contact discontinuity under a perturbation of the Riemann initial data. This shows the instability and the internal mechanism of a delta shock. Furthermore, we find that the Riemann solution of the hyperbolic system is instable under this perturbation, which is also quite different from the previous perturbed Riemann problems.

Measure-Valued Solutions to a Non-Strictly Hyperbolic System with Delta-Type Riemann Initial Data

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Shuangrong Li ◽  
Chun Shen
Keyword(s):  
Shock Wave ◽  
Initial Data ◽  
Riemann Problem ◽  
Contact Discontinuity ◽  
Initial Condition ◽  
Global Measure ◽  
Delta Shock Wave ◽  
Dirac Delta ◽  
Delta Shock ◽  
Delta Type

AbstractThis paper is concerned with the construction of global measure-valued solutions to the extended Riemann problem for a non-strictly hyperbolic system of two conservation laws with delta-type initial data. The wave interaction problems have been extensively studied for all kinds of situations by using the initial condition consisting of constant states in three pieces instead of delta-type initial data under the perturbation method. The measure-valued solutions of the extended Riemann problem are achieved constructively when the perturbed parameter tends to zero. During the process of constructing solutions, a new and interesting nonlinear phenomenon is discovered, in which the initial Dirac delta function travels along the trajectory of either delta shock wave or contact discontinuity (or delta contact discontinuity). Moreover, a delta shock wave is separated into a delta contact discontinuity and a shock wave during the process of delta shock wave penetrating a composite wave composed of a rarefaction wave and a contact discontinuity. In addition, we further consider the constructions of global measure-valued solutions when the initial condition contains Dirac delta functions at two different initial points.

scholarly journals On the delta shockwave interactions for the isentropic Chaplygin gas system consisting of three scalar equations

Filomat ◽  
2019 ◽  
Vol 33 (16) ◽  
pp. 5355-5373 ◽  
Author(s):  
Meina Sun ◽  
Jie Xin
Keyword(s):  
Shock Wave ◽  
Initial Data ◽  
Riemann Problem ◽  
Propagation Speed ◽  
Chaplygin Gas ◽  
Euler System ◽  
Delta Shock Wave ◽  
Riemann Solutions ◽  
Delta Shock ◽  
Scalar Equations

The Riemann problem for the one-dimensional version of isentropic compressible Euler system for the Chaplygin gas consisting of three scalar equations is considered. It is shown that the Riemann solutions involve only two situations: the combination of three contact discontinuities or a delta shock wave. The generalized Rankine-Hugoniot conditions of delta shock wave are derived and the exact delta shock wave solution including the strength and propagation speed is obtained explicitly. The solutions to the perturbed Riemann problem are constructed globally when the initial data are taken to be the three piecewise constant initial data. The wave interaction problem is extensively investigated and some interesting phenomena are observed. It is shown that the limits of solutions to the perturbed Riemann problem converge to the corresponding ones to the Riemann problem when the perturbation parameter tends to zero.

scholarly journals The Perturbed Riemann Problem for Special Keyfitz-Kranzer System with Three Piecewise Constant States

2017 ◽  
Vol 2017 ◽  
pp. 1-12
Author(s):  
Yuhao Jiang ◽  
Chun Shen
Keyword(s):  
Initial Data ◽  
Riemann Problem ◽  
Global Solutions ◽  
Wave Interactions ◽  
Small Perturbations ◽  
Riemann Solutions ◽  
Piecewise Constant

The Riemann problem for a special Keyfitz-Kranzer system is investigated and then seven different Riemann solutions are constructed. When the initial data are chosen as three piecewise constant states under suitable assumptions, the global solutions to the perturbed Riemann problem are constructed explicitly by studying all occurring wave interactions in detail. Furthermore, the stabilities of solutions are obtained under the specific small perturbations of Riemann initial data.

scholarly journals Determination of Avalanche Dynamics Friction Coefficients from Measured Speeds

1983 ◽  
Vol 4 ◽  
pp. 170-173 ◽  
Author(s):  
D. M. McClung ◽  
P. A. Schaerer
Keyword(s):  
Complex Terrain ◽  
Sliding Friction ◽  
Numerical Solutions ◽  
Analytic Solutions ◽  
Dynamics Model ◽  
Friction Coefficients ◽  
Turbulent Friction ◽  
Constant Friction ◽  
Avalanche Dynamics

An avalanche dynamics model, appropriate for complex terrain, for real avalanche paths was developed by Perla, Cheng and McClung in 1980. The model has two friction terms, one for sliding friction which is independent of speed, and one for turbulent friction which is proportional to V2, where V is the centre-of-mass speed along the incline. By introducing speed maxima for avalanches, along with start and stop reference positions, it is possible to determine the the two constant friction coefficients for the model. When this is done, it is found that speed data often exceed a model speed limit implied by the application of V = 0 at the start and stop positions. This effect is illustrated by analytic solutions of the relevant equations, as well as numerical solutions for actual avalanche paths. Some limitations and properties of the fundamental modelling are outlined and suggestions given for future use of such models.

The analytical solution of the Riemann problem in relativistic hydrodynamics

1994 ◽  
Vol 258 ◽  
pp. 317-333 ◽  
Author(s):  
José Ma Martí ◽  
Ewald Müller
Keyword(s):  
High Resolution ◽  
Analytical Solution ◽  
Riemann Problem ◽  
Shock Capturing ◽  
Relativistic Hydrodynamics ◽  
Minkowski Space Time ◽  
Intermediate States ◽  
Relativistic Flow ◽  
Initial Discontinuity ◽  
The Impact

We consider the decay of an initial discontinuity in a polytropic gas in a Minkowski space–time (the special relativistic Riemann problem). In order to get a general analytical solution for this problem, we analyse the properties of the relativistic flow across shock waves and rarefactions. As in classical hydrodynamics, the solution of the Riemann problem is found by solving an implicit algebraic equation which gives the pressure in the intermediate states. The solution presented here contains as a particular case the special relativistic shock-tube problem in which the gas is initially at rest. Finally, we discuss the impact of this result on the development of high-resolution shock-capturing numerical codes to solve the equations of relativistic hydrodynamics.

scholarly journals Resonant Stellar Orbits in Spiral Galaxies

1975 ◽  
Vol 69 ◽  
pp. 237-244
Author(s):  
P. O. Vandervoort
Keyword(s):  
Excellent Agreement ◽  
Spiral Galaxy ◽  
Harmonic Balance ◽  
Spiral Galaxies ◽  
Numerical Solutions ◽  
Equations Of Motion ◽  
Analytic Solutions ◽  
Stellar Orbits ◽  
Method Of Harmonic Balance ◽  
Resonance Phenomena

This paper reviews a series of investigations of the orbits of stars in the regions of the Lindblad resonances of a spiral galaxy. The analysis is formulated in an epicyclic approximation. Analytic solutions of the epicyclic equations of motion are obtained by the method of harmonic balance of Bogoliubov and Mitropolsky. These solutions represent the resonance phenomena exhibited by the orbits in generally excellent agreement with numerical solutions.

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