Document Type

Conference Proceeding

Conference

2004 5th International Symposium on Computational Technologies for Fluid/Thermal/Chemical Systems with Industrial Applications

Publication Date

7-2004

Research Focus Area

Computational Fluid Dynamics

DOI

10.1115/PVP2004-3119

City

San Diego/La Jolla, California

Abstract

The feasibility to implement fast-chemistry reactions in a three-dimensional large eddy simulation (LES) of a turbulent reacting flow using a filtered density function (PDF) technique is studied. Low-density polyethylene (LDPE) is used as an representative reaction due to the stiff nature of the ordinary differential equation (ODE's) describing the kinetics. In FDF/LES, the chemistry needs to be evaluated many times for a large number of fictitious particles that are tracked in the flow, and therefore a constraint is put to the CPU time needed to solve the kinetics. Pope (1997) developed an in situ adaptive tabulation (ISAT) to treat complex chemistry computationally very efficiently when many evaluations of the chemistry are needed. Kolhapure and Fox (1999) successfully applied IS AT to LDPE using a quasi steady state assumption (QSSA). In the present paper, the aim is to optimize the latest version (ISAT Version 4.0, Pope, 2003) for the full LDPE reaction (i.e. without QSSA), in terms of accuracy and speed up by varying the error tolerance and the number of trees used by ISAT. For this purpose, a pairwise mixing stirred reactor (PMSR) is employed, since it forms a stringent test for the chemistry solver due to the large accessed region of composition space that can be established. For a number of trees of Ntree = 8 and an error tolerance of εtol = 10-5 the best overall performance of ISAT was obtained: compared with direct integration, a speed up factor of more than ten combined with an relative error in temperature of about 1% was found.

Comments

This is an article from Proceedings of PVP01 2004 5th International Symposium on Computational Technologies for Fluid/Thermal/Chemical Systems with Industrial Applications held in San Diego/La Jolla, California, July 25-29.American Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP (2004): 491 (2), pp. 51-58. doi: 10.1115/PVP2004-3119.

Copyright Owner

ASME

Language

en

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