We presently derive generalized expressions of the stress tensor for continuum bodies
with varying mass, considering both the Lagrangian and Eulerian viewpoints in
continuum mechanics. We base our analysis and derivation of the expressions of both
Cauchy and Eshelby stress tensors on an extension of the virial theorem
for both discrete and continuous systems of material points with variable
mass. The proposed framework is applicable to describe physical systems at
very different scales, from the evolution of a population of biological cells
accounting for growth to mass ejection phenomena occurring within a collection of
gravitating objects at the very large astrophysical scales. As a starting basis,
the field equations in continuum mechanics are written to account for a
mass source and a mass flux, leading to a formulation of the virial theorem
accounting for a varying mass within the considered system. The scalar and
tensorial forms of the virial theorem are written successively in both Lagrangian
and Eulerian formats, incorporating the mass flux. This delivers generalized
formal expressions of Cauchy and Eshelby stress tensors versus the average
tensor spatial and material virials respectively, incorporating the mass flux
contribution.
Keywords
continuum bodies with changing mass, generalized virial
theorem, discrete mechanics, mass flux, Eshelby stress