Viscosity of a Mixture

on . Posted in Fluid Dynamics

Viscosity of a mixture refers to the measure of the resistance of the mixture to deformation or flow.  It is a property in fluid dynamics and is often influenced by the types and amounts of individual components in the mixture.  The viscosity of a mixture depends on the viscosities of its individual components, their concentrations, and the interactions between the components.

concepts related to viscosity in mixtures

There are different models and methods to estimate or calculate the viscosity of a mixture, and the appropriate approach depends on the nature of the mixture.

  • Mixing Rules  -  In some cases, simple mixing rules are used to estimate the viscosity of a mixture based on the viscosities of its individual components and their concentrations.
  • Empirical Models  -  Various empirical models have been developed to predict the viscosity of mixtures.  These models often involve fitting parameters based on experimental data.
  • Effective Medium Theories  -  Some theoretical approaches consider the mixture as an effective medium with properties derived from the properties of its individual components.  These theories may account for interactions between molecules in the mixture.
  • Correlations and Experiments  -  In practice, viscosity of mixtures is often determined experimentally, and correlations are developed based on the experimental data.  These correlations can be specific to certain types of mixtures or systems.

It's important to note that the viscosity of a mixture is not always a simple linear combination of the viscosities of its components.  The interactions between molecules in the mixture, such as molecular size, shape, and attractive forces, can significantly influence the overall viscosity.  For precise information on the viscosity of a specific mixture, experimental measurements or detailed modeling based on the properties of individual components may be necessary.


Viscosity of a Mixture formula

\( \mu = \sum \; ( \mu_i \; y_i \; \sqrt{M_i}  )   \;/\;   \sum\; (y_i \; \sqrt{M_i} )   \) 
Symbol English Metric
\( \mu \)  (Greek symbol mu) = dynamic viscosity of the gas mixture \(lbf-sec \;/\; ft^2\) \(Pa-s\)
\( \mu_i \)  (Greek symbol mu) = dynamic viscosity of gas component \(lbf-sec \;/\; ft^2\) \(Pa-s\)
\( y_i \) = mole fraction or percent of gas component \(dimensionless\)
\( M_i \) = molecular weight of gas component \(lbm \;/\; lbmol\) \(kg \;/\; kmol\)

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Tags: Viscosity