The role of effects due to nonlocality and delay in transfer processes in microstructured media

The role of effects due to nonlocality and delay in irreversible transfer processes, which arise after taking into account nonequilibrium phenomena in the medium structure is studied. By an example of the isothermal response of the medium to an instantaneous perturbation of shear velocity, the evolution of stress-tensor components is studied. It is shown that, in a medium of constant density, its strained state is determined by the tangent shear stress, by the first and second differences of normal stresses, and by the relaxation of these differences to their equilibrium values in an oscillatory process with a decaying amplitude. In this case, thermodynamic variables of state “pressure tensor and internal energy” are functions of shear velocity and time. It is found that the approximation of locally equilibrium thermodynamics is valid for microstructured media if their relaxation times are an order of magnitude shorter than the characteristic time of the problem.