Treatment of fast chemistry in FDF/LES: In situ adaptive tabulation

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2004-07-01
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E., van Vliet
Derksen, J.
Pope, S.
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Fox, Rodney
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Chemical and Biological Engineering

The function of the Department of Chemical and Biological Engineering has been to prepare students for the study and application of chemistry in industry. This focus has included preparation for employment in various industries as well as the development, design, and operation of equipment and processes within industry.Through the CBE Department, Iowa State University is nationally recognized for its initiatives in bioinformatics, biomaterials, bioproducts, metabolic/tissue engineering, multiphase computational fluid dynamics, advanced polymeric materials and nanostructured materials.

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The Department of Chemical Engineering was founded in 1913 under the Department of Physics and Illuminating Engineering. From 1915 to 1931 it was jointly administered by the Divisions of Industrial Science and Engineering, and from 1931 onward it has been under the Division/College of Engineering. In 1928 it merged with Mining Engineering, and from 1973–1979 it merged with Nuclear Engineering. It became Chemical and Biological Engineering in 2005.

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1913 - present

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  • Department of Chemical Engineering (1913–1928)
  • Department of Chemical and Mining Engineering (1928–1957)
  • Department of Chemical Engineering (1957–1973, 1979–2005)
    • Department of Chemical and Biological Engineering (2005–present)

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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.

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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.

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Thu Jan 01 00:00:00 UTC 2004