학술논문

Inversion of equations of state by combining multi-task neural networks and Newton's method.
Document Type
Article
Source
Inverse Problems in Science & Engineering. Dec 2021, Vol. 29 Issue 13, p3490-3508. 19p.
Subject
*NEWTON-Raphson method
*EQUATIONS of state
*HEPTANE
*NONLINEAR equations
*PHASE transitions
*DEEP learning
Language
ISSN
1741-5977
Abstract
In this work, we address the problem of numerical multidimensional inversion of equations of state for fluid dynamic problems. Particularly, we study the cases where the thermodynamic region of interest contains phase transitions with possible discontinuities of derivatives. In these cases, straight applications of common iterative solvers such as Newton's method with fixed initial guess may lead to divergences. To address this issue, we present a novel method for inverting non-linear equations. The method combines deep multi-task learning techniques with an iterative solver such as Newton's method and allows to handle non-linear equations of complex structure. In order to test the efficiency of the new approach, we apply the method to the problem of inverting equations of state for the pure fluids water, heptane and ethanol. We observe that the proposed method allows to significantly speed-up inversion and avoid divergences, especially in the vicinity of phase boundaries. [ABSTRACT FROM AUTHOR]