Mixture theory is used to model multiphase systems using the principles of

continuum mechanics Continuum mechanics is a branch of mechanics that deals with the mechanical behavior of materials modeled as a continuous mass rather than as discrete particles. The French mathematician Augustin-Louis Cauchy was the first to formulate such m ...

generalised to several interpenetrable continua. The basic assumption is that, at any instant of time, all phases are present at every material point, and

momentum In Newtonian mechanics, momentum (more specifically linear momentum or translational momentum) is the product of the mass and velocity of an object. It is a vector quantity, possessing a magnitude and a direction. If is an object's mass an ...

and

mass balance In physics, a mass balance, also called a material balance, is an application of conservation of mass to the analysis of physical systems. By accounting for material entering and leaving a system, mass flows can be identified which might have bee ...

equations are postulated. Like other models, mixture theory requires

constitutive relations In physics and engineering, a constitutive equation or constitutive relation is a relation between two physical quantities (especially kinetic quantities as related to kinematic quantities) that is specific to a material or substance, and approxi ...

to close the system of equations. Krzysztof Wilmanski extended the model by introducing a balance equation of porosity.

References

{{reflist Rheology Scientific modelling