General guidelines, relevant to the present work, follow below. Through the contact mode, only density exhibits a jump while thermal pressure, velocity and magnetic field are continuous. The robustness of the new algorithm is validated against one- and two-dimensional numerical test problems. In the classical limit, our derivation does not coincide with the approximate Riemann solvers constructed by Gurski or Li The configuration adopted here corresponds to model C2-pol-1 in Leismann et al.

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Hhllc18 6: The full characteristic decomposition of the RMHD equation i. In terms of computational cost, employment of exact relativistic Riemann solvers may become prohibitive due to the high degree of intrinsic nonlinearity present in the equations. The reader might have noticed that in the limit of vanishing B xsome of the expressions given in Section 3.

Magnetic field lines are squeezed in the y direction building up a shell of higher magnetic pressure.

They are heavily used in computational fluid dynamics and computational magnetohydrodynamics. The expanding region is delimited by a fast forward shock propagating nearly radially at almost the speed of light. Since similar errors were also reported by BA, and the same conclusions have been drawn in Paper I, we raise the question as to whether the degree of this pathology grows with the complexity of the Riemann solver.

In the standard Godunov-type formalism, numerical integration of 9 depends on the computation of numerical fluxes at zone interfaces. Future, more specific works should address this problem. Dark matter heats up in dwarf galaxies.

Transverse components may be discontinuous. Despite the higher accuracy in reproducing the full wave structure, these solvers rely on rather expensive characteristic decompositions of the Jacobian matrix. All articles with unsourced statements Articles with unsourced statements from October In absence of the singular behavior described in Section 3.

There are special cases where it is possible to handle some of the degeneracies more efficiently using simple analytical formulae:. Relativisitc Brio—Wu shock tube problem. These solvers were introduced by Nishikawa and Kitamura, [8] in order to overcome the carbuncle problems of the Roe solver and the excessive diffusion of the HLLE solver at the same time.

Under this condition, the approximate solution outlined in Paper I can still be applied with minor modifications; see Section 3. Multidimensional integration has been formulated in a versatile and efficient way within the framework of the CTU method.

Riemann solver - Wikipedia

Retrieved from " https: Cylindrical explosions in cartesian coordinates are particular useful in checking the robustness hllv the code and the algorithm response to different kinds of degeneracies. The most popular solvers are:. In the CT approach a new staggered magnetic field variable is introduced.

This task is accomplished by the exact or approximate solution of the initial value problem:.

Riemann solver

Interpolation in the y -direction is done in a similar manner. Fluids57 Similar conclusions have been drawn by previous investigators.

Greek indexes run from 0 to 3 and are customary for covariant expressions involving four vectors. The resulting numerical scheme is simple to implement, efficient and suitable for a general equation of state.

Physics > Computational Physics

Compute the time-centred area weighted magnetic field using Stoke's theorem We hllv like to thank Andria Rogava for helpful suggestions and comments on the recovery of primitive variables from conservative ones. The Courant number is 0. Following KO, we use 32 equally spaced contour levels between 0.

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