Ordinary Thermodynamics provides reliable results for problems with fairly smooth and slowly varying fields. For rapidly changing fields or steep gradients Extended Thermodynamics (ET) [1] provides better results. The new version of ET, the so-called Consistently Ordered Extended Thermodynamics [2], assigns an order of magnitude in steepness to the variables. In [2] the authors use as variables the moments G, constructed from the irreducible parts of Hermite polynomials in the components c i of the atomic velocity. With this choice of variables the closure is automatic once an order is assigned to a process. But, in terms of the G's, the equations look complicated and it is quite difficult to derive them. In this paper we consider the equations in terms of the usual F-moments, constructed with simple polynomials in c i . By assigning an order to the variables, we derive the field equations appropriate to two different one-dimensional processes: heat conduction in a gas at rest and heat conduction with one-dimensional motion. Comparison with [2] shows that the sets of the field equations coincide, but, in terms of the F's, the equations are less complicated and they may be obtained easily.

Consistently ordered extended thermodynamics - a proposal for an alternative method

BARBERA, Elvira
2005

Abstract

Ordinary Thermodynamics provides reliable results for problems with fairly smooth and slowly varying fields. For rapidly changing fields or steep gradients Extended Thermodynamics (ET) [1] provides better results. The new version of ET, the so-called Consistently Ordered Extended Thermodynamics [2], assigns an order of magnitude in steepness to the variables. In [2] the authors use as variables the moments G, constructed from the irreducible parts of Hermite polynomials in the components c i of the atomic velocity. With this choice of variables the closure is automatic once an order is assigned to a process. But, in terms of the G's, the equations look complicated and it is quite difficult to derive them. In this paper we consider the equations in terms of the usual F-moments, constructed with simple polynomials in c i . By assigning an order to the variables, we derive the field equations appropriate to two different one-dimensional processes: heat conduction in a gas at rest and heat conduction with one-dimensional motion. Comparison with [2] shows that the sets of the field equations coincide, but, in terms of the F's, the equations are less complicated and they may be obtained easily.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11570/1432953
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