G.1.8 Partial Differential Equations
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It is the ultimate goal of concurrent multiscale methods to
provide computational tools that allow to simulation physical processes
with the accuracy of micro-scale and the computational speed of
macro-scale models. As a matter of fact, the efficient and scalable
implementation of concurrent multiscale methods on clusters and supercomputers
is a complicated endeavor. In this article we present the parallel
multiscale simulation tool MACI which has been designed for
efficient coupling between molecular dynamics and finite element codes.
We propose a specification for a thin yet versatile interface for the
coupling of molecular dynamics and finite element codes in a modular
fashion. Further we discuss the parallelization strategy pursued in
MACI, in particular, focusing on the parallel assembly of transfer
operators and their efficient execution.
Recently the unsteady response of 1-D premixed flames to acoustic pressure waves for the range of frequencies below and above the inverse of the flame transit time was investigated experimentally by Wangher et al. using OH chemiluminescence. They compared the frequency dependence of the measured response to the prediction of an analytical model proposed by Clavin et al., derived from the standard flame model (one-step Arrhenius kinetics). Discrepancies between the experimental results and the model led to the conclusion that the standard model does not provide an adequate description of the unsteady response of real flames and that it is necessary to investigate more realistic chemical models. Here we follow exactly this suggestion and perform numerical studies of the reponse of lean methane flames using different reaction mechanisms. We find that the global flame response obtained with both detailed chemistry (GRI3.0) and a reduced multi-step model by Peters lies slightly above the predictions of the analytical model, but is close to experimental results. We additionally used an irreversible one-step reaction model which yields good results at least for frequencies close to the inverse flame transit time.