Minimization Technique for Phase Equilibrium ...

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Minimization Technique for Phase Equilibrium Computation in Multicomponent Two-phase Flows

Name:Personal
Vankova, Irena
Role :Text(marcrelator)
creator

Name:Personal
Furtado, Dr. Frederico
Role :Text(marcrelator)
contributor

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still image
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Laramie, Wyoming

University of Wyoming
(keyDate="yes")
2009-05-18

Language:Text
eng

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abstract
The focus of this research project is to develop a minimization procedure of the Gibbs free energy function for a multi-component two-phase flow problem. The procedure is based on the Newton’s method. In order to make this method suitable for the problem, the following improvements were investigated: (i) modification of the Hessian matrix to guarantee its positive definiteness – this modification prevents the convergence to a saddle point (i.e., an unstable thermodynamic equilibrium); (ii) adjustment of the size of the Newton step in order to reach the local minimum with a low number of iterations, even when one starts relatively far from the equilibrium point, the same also prevents from overshooting the local minimum. One of the biggest difficulties related to the thermodynamic equilibrium problem is to find a method that accurately determines the Newton step of a nearly singular system. In second part of the method description, a modification to computing the Newton’s step is discussed to address this problem. The nearly singular direction of the Hessian matrix is isolated by means of an orthogonal transformation (Householder Transformation). As a result, the matrix should be factorized accurately. A comparison of the two versions of the minimization method will be discussed.
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From - Undergraduate Research Day 2009 - Celebration of Research - Abstracts
Subject
Gibbs free energy function minimization

Subject
Hessian matrix -- orthogonal transformation

Subject
Householder Transformation

Related Item:series Title Information
Undergrauate Research Day 2009

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http://digital.uwyo.edu/copyright.htm
Record Information languageOfCataloging :Text(ISO639-2B)
English
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eng