Variational Principles in Thermodynamics

Authors

  • W. Muschik
  • P. Ván
  • C. Papenfuss

Abstract

Instead of equations of motion, variational principles are often used for describing the dynamical behavior of a system. If the equations of motion are variational self-adjoint, the variational principle is equivalent to the equations of motion, because those are given by the Euler-Lagrange equations which belong to the variational principle. If the equations of motion are not variational self-adjoint -as it is the general case in thermodynamics- procedures are discussed to obtain also in these cases a variational problem. Because of lack of variational self-adjointness these variational problems cannot be true ones, they are non-Hamiltonian. By presupposing suflicient conditions an evolution criterion can be derived from the Second Law which results in a Hamiltonian variational principle, also in thermodynamics.

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Published

2019-09-19

How to Cite

Muschik, W., Ván, P. and Papenfuss, C. (2019) “Variational Principles in Thermodynamics”, Technische Mechanik - European Journal of Engineering Mechanics, 20(2), pp. 105–112. Available at: https://journals.ub.ovgu.de/index.php/techmech/article/view/1080 (Accessed: 13 November 2024).

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