Hybrid fluid / kinetics solvers for time-dependent problems in MHD. We will extend the AMR MHD fluids codes developed in FY02 and FY03 to the case of hybrid fluid-particle models. For example, energetic ion species produced by fusion reactions in the plasma are represented using a gyrokinetic model, with the electrons and bulk ions represented by a fluid. This is the first of a hierarchy of such models, that range up to using a phase-space description of all of the ions, with the fluid representation used only for the electrons.
Combustion. During the first part of FY04, we will focus the simulation capabilites toward modeling two classes of lean premixed flames, both of which are under active experimental investigation in the Environmental Sciences Division at LBNL. In both cases, a quasi-steady flame is stabilized above a circular nozzle, modified to produce turbulent outflow. In one case, a swirl component is added to the flow, and the flame stabilizes in the recirculation zone above the orifice due to the fuel expanding radially by centrifugal force. In the second case, a thin wire across the center of the pipe outflow creates a V-shaped recirculation. The first data to be collected will characterize overall flame features such as cone height and flame brush thickness. Eventually, OH-PLIF imaging and particle image velocimetry will be used to map the flame and velocity field. Full three-dimensional time-dependent models will be used with detailed chemistry to capture the flame-anchoring and time-dependent flame shape perturbations. Funding and time-permitting, we will expand these activities to include simulations of a new high-pressure facility at LBNL. This configuration produces a bunsen-type flame at up to 5 atmospheres, and will burn premixed methane-air mixtures at equivalence ratio 0.8.