Complex fluids subjected to external influences

The aim of this paper is to develop a unifying framework for discussing dyn amics and thermodynamics of externally driven fluids. Since the levels on w hich the driving force is defined and the dynamics is discussed are often d ifferent, the analysis is conducted and interpreted in the context of multi level realizations (developed in this paper) of the unifying framework prov ided by generalized Hamiltonian structures. The framework is based on the e xperimentally established fact of the existence of reduced descriptions of both isolated and driven macroscopic systems. Thermodynamics of externally unforced as well as driven complex fluids arise from the general concept of thermodynamics introduced in the unifying framework. (C) 2001 Elsevier Sci ence B.V. All rights reserved.