Bitangent planes of surfaces and applications to thermodynamics

Giblin, Peter and Reeve, Graham (2023) Bitangent planes of surfaces and applications to thermodynamics. JOURNAL OF GEOMETRY AND PHYSICS, 192. p. 104920.

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Official URL: http://dx.doi.org/10.1016/j.geomphys.2023.104920

Abstract

The classical van der Waals equation, applied to one or two mixing fluids, and the Helmholtz (free) energy function A yield, for fixed temperature T, a curve in the plane R2 (one fluid) or a surface in 3-space R3 (binary fluid). A line tangent to this curve in two places (bitangent line), or a set of planes tangent to this surface in two places (bitangent planes) have a thermodynamic significance which is well documented in the classical literature. Points of contact of bitangent planes trace ‘binodal curves’ on the surface in R3. The study of these bitangents is also classical, starting with D.J. Korteweg and J.D. van der Waals at the end of the 19th century, but continuing into modern times. In this paper we give a summary of the thermodynamic background and of other mathematical investigations and then present a new mathematical approach which classifies a wide range of situations in R3 where bitangents occur. In particular, we are able to justify many of the details in diagrams of binodal curves observed by Korteweg and others, using techniques from singularity theory.

Item Type:	Article
Uncontrolled Keywords:	Binary fluid, Binodal, Bitangent, Criminant, Helmholtz free energy, Van der Waals equation
Divisions:	Faculty of Science and Engineering > School of Physical Sciences
Depositing User:	Symplectic Admin
Date Deposited:	21 Sep 2023 07:24
Last Modified:	21 Sep 2023 07:24
DOI:	10.1016/j.geomphys.2023.104920
Related URLs:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3172909