The thermonuclear explosion of a massive white dwarf in a Type Ia supernova explosion is characterized by vastly disparate spatial and temporal scales. The extreme dynamic range inherent to the problem prevents the use of direct numerical simulation and forces modelers to resort to subgrid models to describe physical processes taking place on unresolved scales. We consider the evolution of a mo...

We analyse numerically the onset of pre-big bang inflation in an inhomogeneous, spherically symmetric Universe. Adding a small dilatonic perturbation to a trivial (Milne) background, we find that suitable regions of space undergo dilaton-driven inflation and quickly become spatially flat (Ω → 1). Numerical calculations are pushed close enough to the big bang singularity to allow cross checks ag...

The study is devoted to mathematical models of mass transfer during diffusion combustion gaseous fuel. A numerical approach presented that makes it possible estimate the effect conditions on length a direct-flow flame. simplified method for calculating heat release in flame applied, taking into account fact chemical reactions are concentrated at front. Some results simulation processes and comp...

We present a systematic survey of the capabilities of type Ia supernova explosion models starting from a number of flame seeds distributed around the center of the white dwarf star. To this end we greatly improved the resolution of the numerical simulations in the initial stages. This novel numerical approach facilitates a detailed study of multi-spot ignition scenarios with up to hundreds of i...

We investigate the propagation of a premixed flame subject to thermal expansion through a narrow channel against a Poiseuille flow of large amplitude. This is the first study to consider the effect of a large-amplitude flow, characterised by a Péclet number of order one, Pe= O(1), on a variable-density premixed flame in the asymptotic limit of a narrow channel. It is also the first study on Tay...

The aim of this work is to model a jet diffusion flame, to show the corresponding proof of existence of solutions, and to present numerical results. The model is based on the flamelet equations for the chemistry and on the mixture fraction for the flow. Numerical tests are carried out for Sandia Flame D and the results are found to compare well with available data found in the literature.

This paper presents our recent progress in terascale three-dimensional simulations of turbulent nonpremixed flames in the presence of a mean flow strain and fine water droplets. Under the ongoing university collaborative project supported by the DOE SciDAC Program [1] along with the INCITE 2007 Project [2], the study aims at bringing the state-of-the-art highfidelity simulation capability to th...

In order to directly control the premixed combustion phasing, a Jet Controlled Compression Ignition (JCCI) for diesel premixed compression ignition systems is investigated. Experiments were conducted on a single cylinder natural aspirated diesel engine without EGR at 3000 rpm. Numerical models were validated by load sweep experiments at fixed spark timing. Detailed combustion characteristics we...