Spatially homogeneous systems are characterized by the simultaneous presence of a wide range of time scales. When the dynamics of such reactive systems develop very-slow and very-fast time scales separated by a range of active time scales, with large gaps in the fast/active and slow/active time scales, then it is possible to achieve multi-scale adaptive model reduction along-with the integration of the governing ordinary differential equations using the G-Scheme framework. The G-Scheme assumes that the dynamics is decomposed into active, slow, fast, and when applicable, invariant subspaces. We derive the expressions that express the direct link between time scales and entropy production by resorting to the estimates provided by the G-Scheme. With reference to a constant volume, adiabatic batch reactor, we compute the contribution to entropy production by the four subspaces. The numerical experiments show that, as indicated by the theoretical derivation, the contribution to entropy production of the fast subspace is of the same magnitude of the error threshold chosen for the numerical integration, and that the contribution of the slow subspace is generally much smaller than that of the active subspace.

Entropy production at all scales / Valorani, Mauro; S., Paolucci. - ELETTRONICO. - (2014). (Intervento presentato al convegno Ninth Mediterranean Combustion Symposium tenutosi a Rodi (Grecia)).

Entropy production at all scales

VALORANI, Mauro;
2014

Abstract

Spatially homogeneous systems are characterized by the simultaneous presence of a wide range of time scales. When the dynamics of such reactive systems develop very-slow and very-fast time scales separated by a range of active time scales, with large gaps in the fast/active and slow/active time scales, then it is possible to achieve multi-scale adaptive model reduction along-with the integration of the governing ordinary differential equations using the G-Scheme framework. The G-Scheme assumes that the dynamics is decomposed into active, slow, fast, and when applicable, invariant subspaces. We derive the expressions that express the direct link between time scales and entropy production by resorting to the estimates provided by the G-Scheme. With reference to a constant volume, adiabatic batch reactor, we compute the contribution to entropy production by the four subspaces. The numerical experiments show that, as indicated by the theoretical derivation, the contribution to entropy production of the fast subspace is of the same magnitude of the error threshold chosen for the numerical integration, and that the contribution of the slow subspace is generally much smaller than that of the active subspace.
2014
Ninth Mediterranean Combustion Symposium
Entropy production; G-Scheme; time scale analysis
04 Pubblicazione in atti di convegno::04b Atto di convegno in volume
Entropy production at all scales / Valorani, Mauro; S., Paolucci. - ELETTRONICO. - (2014). (Intervento presentato al convegno Ninth Mediterranean Combustion Symposium tenutosi a Rodi (Grecia)).
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/650664
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