mixture theory

Mixture theory is used to model multiphase systems using the principles of continuum mechanics generalised to several interpenetrable continua.{{cite book

|author=Bowen,R. M.

|editor=Eringen, A. C.

|title=Theory of Mixtures, Part I

|series=Continuum Physics |volume=III

|year=1976

|publisher=Academic Press

|location=New York, USA}} The basic assumption is that, at any instant of time, all phases are present at every material point, and momentum and mass balance equations are postulated. Like other models, mixture theory requires constitutive relations to close the system of equations. Krzysztof Wilmanski extended the model by introducing a balance equation of porosity.{{cite journal

|author=Wilmanski, Krzysztof

|title=Porous Media at Finite Strains. The New Model with the Balance Equation of Porosity

|journal=Archives of Mechanics

|volume=48

|number=4

|pages=591–628

|year=1996}}{{cite book

|author=Wilmanski, Krzysztof

|title=Thermomechanics of Continua

|year=1998

|publisher=Springer

|location=Heidelberg, Germany}}