[en] A spectral-like viscosity is proposed for centered differencing schemes to help stabilize numerical solutions and reduce oscillations near discontinuities. Errors introduced by the added dissipation can be made arbitrarily small by adjusting the power of the derivative in the viscosity term. The high-wavenumber viscosity is combined with a 10th-order compact scheme to produce an accurate and efficient shock-capturing method. The new scheme compares favorably with other shock-capturing algorithms

[en] Approximate thermodynamic state relations for multicomponent atomic and molecular gas mixtures are often constructed by artificially partitioning the mixture into its constituent materials and requiring the separated materials to be in temperature and pressure equilibrium. Iterative numerical algorithms have been employed to enforce this equilibration and compute the resulting approximate state relations in single-temperature mixtures. In partially ionized gas mixtures, there is both theoretical and empirical evidence that equilibrating the chemical potentials, number densities, or partial pressures of the free electrons is likely to produce more accurate results than equilibrating the total pressures. Moreover, in many situations of practical interest the free electrons and heavy particles have different temperatures. In this paper, we present a generalized algorithm for equilibrating the heavy-particle and electron temperatures and a third user-specified independent thermodynamic variable in a two-temperature plasma mixture. Test calculations based on the equilibration of total pressure vs. electron pressure are presented for three different mixtures

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