1. Self-consistent solution of cosmological radiation-hydrodynamics and chemical ionization

    Journal of Computational Physics 228(18):6833 (2009)

    We consider a PDE system comprising compressible hydrodynamics, flux-limited diffusion radiation transport and chemical ionization kinetics in a cosmologically-expanding universe. Under an operator-split framework, the cosmological hydrodynamics equations are solved through the piecewise pa...
  2. Piecewise parabolic method on a local stencil for magnetized supersonic turbulence simulation

    Journal of Computational Physics 228(20):7614 (2009)

    Stable, accurate, divergence-free simulation of magnetized supersonic turbulence is a severe test of numerical MHD schemes and has been surprisingly difficult to achieve due to the range of flow conditions present. Here we present a new, higher order-accurate, low dissipation numerical meth...
  3. The formation of the first star in the Universe.

    Science 295(5552):93 (2002) PMID 11711636

    We describe results from a fully self-consistent three-dimensional hydrodynamical simulation of the formation of one of the first stars in the Universe. In current models of structure formation, dark matter initially dominates, and pregalactic objects form because of gravitational instability fr...
  4. The formation of the first star in the Universe.

    Science 295(5552):93 (2002) PMID 11711636

    We describe results from a fully self-consistent three-dimensional hydrodynamical simulation of the formation of one of the first stars in the Universe. In current models of structure formation, dark matter initially dominates, and pregalactic objects form because of gravitational instability fr...
  5. Modeling primordial gas in numerical cosmology

    New Astronomy 2(3):181 (1997)

    We have reviewed the chemistry and cooling behavior of low-density (n ≲ 10 4 cm −3) primordial gas and devised a model which involves 19 collisional and 9 radiative processes and is applicable for temperatures in the range 1 K < T < 10 8K. In a companion paper (Anni...
  6. Cosmological hydrodynamics with multi-species chemistry and nonequilibrium ionization and cooling

    New Astronomy 2(3):209 (1997)

    We have developed a method of solving for multi-species chemical reaction flows in nonequilibrium and self-consistently with the hydrodynamic equations in an expanding FLRW universe. The method is based on a backward differencing scheme for the required stability when solving stiff sets of ...
  7. A piecewise parabolic method for cosmological hydrodynamics

    Computer Physics Communications 89(1):149 (1995)

    We describe a hybrid scheme for cosmological simulations that incorporates a Lagrangean particle-mesh (PM) algorithm to follow the collisionless matter with the higher order accurate piecewise parabolic method (PPM) to solve the equations of gas dynamics. Both components interact through th...
  8. Adaptive-grid methods with asymmetric time-filtering

    Computer Physics Communications 36(2):121 (1985)

    We identify the three essential parts for a successful and robust adaptive grid distribution equation for systems of nonlinear partial differential equations: (1) the spatial function, which is composed of operators that control the shape and size of zones, and guarantees the stabili...
  9. Shocks, interfaces, and patterns in supersonic jets

    Physica D: Nonlinear Phenomena 12(1):83 (1984)

    Supersonic gaseous jets exhibit coherent nonlinear dynamic structures. We use a supercomputer to obtain solutions to the equations of two-dimensional inviscid hydrodynamics, representing both axisymmetric and planar jets boring their way through a uniform medium. We use color images to disp...
  10. Adaptive mesh techniques for fronts in star formation

    Physica D: Nonlinear Phenomena 12(1):408 (1984)

    We present an implicit, adaptive-grid, finite-difference technique specifically designed to locate and track arbitrary fronts, interfaces and structures in a radiation hydro flow. The adaptive mesh is constructed in such a way that the “average” change of the flow-variables per grid zone is...
  11. Adaptive-mesh radiation hydrodynamics—I. The radiation transport equation in a completely adaptive coordinate system

    Journal of Quantitative Spectroscopy and Radiat... 31(6):473 (1984)

    We formulate the radiation transport equation in a completely adaptive coordinate system, which we define as a system in which the mesh in spacetime, angles and frequency adapts automatically to the dynamical evolution of the radiation field and fluid flow.
  12. Adaptive-mesh radiation hydrodynamics—II. The radiation and fluid equations in relativistic flows

    Journal of Quantitative Spectroscopy and Radiat... 31(6):479 (1984)

    We derive the radiation and fluid equations for relativistic flows in conservative from in a completely adaptive coordinate system.