A Non Local Equilibrium Model for the Constitutive Equations of a Non-Uniform Simple Fluid

A. Salcido (Mexico)


Non-equilibrium and non-uniform fluids, nonlinear constitutive equations, mathematical modelling.


A slightly generalization of linear irreversible thermodynamics is suggested by considering the first gradients of mass density and velocity as additional state variables in the fundamental state equation of energy for a non-uniform simple fluid system. It is shown that consistence of this hypothesis with the energy balance equation leads to generalized nonlinear constitutive equations for pressure and the stress tensor. The resulting equations were used to obtain the explicit forms of pressure and stress tensor for two energy expressions already reported in literature. In the first case, an specific internal energy obtained by means of molecular dynamics simulations was considered as the starting point to find out the generalized constitutive equations; and in the second one, it was considered the well-known square gradient approximation for energy.

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