Sommario
Si considera un continuo micropolarc, i cui punti materiali sono dotati di momento magnetico, in presenza di un campo magnetico nell'approssimazione della quasimagnetostatica. Dopo aver dedotto le equazioni di bilancio mediante un opportuno procedimento di media, si esamina la compatibilità tra effetti di interazione spaziale e seconda legge della termodinamica e si mostra che tali effetti possono essere presenti solo nelle equazioni costitutive per lo stress dissipativo (di Cauchy)DT.lo stress dissipativo delle coppieDm e il flusso di calore q. Inoltre, in conseguenza della disuguaglianza di dissipazione ridotta, si osserva che una teoria lineare permetterebbe solo una dipendenza diDT,Dm, q dal gradiente di velocità, dalla velocità angolare, dal gradiente della velocità angolare e dal gradiente di temperatura.
Summary
We consider a micropolar continuum, whose material points are endowed with magnetic moment, in the presence of a magnetic field within the approximation of the quasimagnetostatics. We deduce the balance equations by a suitable averaging technique and then we examine the compatibility of spatial interaction effects with thermodynamics. As a result, we show that such effects are confined to the constitutive equations for the dissipative stressDT, the dissipative couple stressDm and the heat flux q. Moreover, as a consequence of the reduced dissipation inequality, a linear theory would account only for a dependence ofDT,Dm, and q on the velocity gradient, the angular velocity, the gradient of the angular velocity, and on the temperature gradient.
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This work was supported by the «Gruppo Nazionale per la Fisica Matematica» of CNR.
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Morro, A. Spatial interaction in magneto-micropolar continua. Meccanica 12, 194–207 (1977). https://doi.org/10.1007/BF02128229
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DOI: https://doi.org/10.1007/BF02128229