Generalization of the Friction Theory for Viscosity Modeling

Abstract

The friction theory (FT) approach relates the viscosity of a fluid to its equation of state (EoS), and it is known to give good results for a large number of compounds over wide ranges of temperature and pressure. Previous FT versions were restricted to use EoS of the van der Waals type, i.e., EoS explicitly consisting of a repulsive and an attractive term, which limited the number of usable EoS as well as the accuracy of the viscosity predictions. In this work, the restriction is removed by means of a pragmatic generalized definition of repulsive and attractive terms based on the internal pressure concept. As a result, the FT theory can be extended to practically all types of EoS, from theoretical ones (e.g., EoS based on thermostatistical or renormalization theories) to the highly accurate empirical reference EoS. In combination with the later, the FT is shown to represent experimental viscosity data for several fluids, including water, with an accuracy as high as that required for reference models. Additionally, some relevant phenomena, such as the critical anomaly, appear to follow naturally from the physics already built into the EoS.

Stereoisomeric effects on dynamic viscosity versus pressure and temperature for the system cis-+trans-decalin

“…Also the friction theory has been coupled to different types of SAFT models [39,45,46]. In a recent paper it is show how the friction theory can be linked to practically any type of EOS [47] ranging from highly theoretical EOS to highly accurate empirical reference EOS.…”

Modeling the viscosity of pure imidazolium-based ionic liquids using SAFT-VR-Mie EoS

“…An underlying assumption central to three models, namely f-theory [9][10][11], Free Volume theory [7,8] and the modified Yarranton−Satyro correlation [41], is that fluid viscosity η can be expressed as the summation of two terms:…”

“…The most popular ones are the free-volume theory (FVT) [7,8], the frictional theory (FT) and subsequent developments [9][10][11], the hard sphere scheme [12,13], extensions of the kinetic-theory to chains, [14,15] scaling relations with the residual entropy [16][17][18] and viscosity correlation such as Yarranton and Satyro method [19].…”

Influence of the chain length on the dynamic viscosity at high pressure of some amines: Measurements and comparative study of some models

“…In the f-theory the density does not appear explicitly, but it is necessary to know the attractive pressure and the repulsive pressure. In a recent paper it is show how the f-theory can be linked to practically any type of EoS [58] ranging from highly theoretical EoS to highly accurate empirical reference EoS. However, the adjustable parameters in this model are linked to the equation of state chosen for the calculation.…”