A simple kinetic model for complex rheological fluids based on irreversible thermodynamics

• Published in: AIChE journal Vol. 66; no. 1
• Main Authors: García‐Sandoval, Juan Paulo, Hernández, Elena, Bautista, Fernando, Puig, Jorge E., Manero, Octavio
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 01-01-2020; American Institute of Chemical Engineers
• Subjects: complex fluids; Computational fluid dynamics; Constants; Constitutive equations; Constitutive relationships; Entanglement; Equations of state; Fluids; Free energy; Gibbs free energy; Kinetics; mathematical modeling; nonequilibrium thermodynamics; Organic chemistry; Rate constants; Rheological properties; Rheology; Shear flow; Thermodynamics; Thickening
• ISSN: 0001-1541; 1547-5905
• DOI: 10.1002/aic.16766

In this work, we analyze the kinetics of the entanglement–disentanglement process of complex fluids coupled to a rheological constitutive equation of state within an irreversible thermodynamics framework. In the context of the coupling between the kinetics and the mechanical phenomena, we assume that the rate constants are functions of the affinities that contain the chemical potentials, which are themselves functions of the extended Gibbs free energy containing the irreversible dissipation terms. Although the derived model has a simple mathematical structure, it is able to predict complex flow behaviors, including shear‐thickening, shear‐thinning, and more complex flow histories such as shear‐banding. As special case, we derive the constitutive equations of the Bautista–Manero–Puig (BMP) model in which the material constants have a thermodynamic basis and have been successfully used for the last two decades to predict the behavior of complex fluids such as the ones examined here.