The following is an elaboration on the linear non-local model of viscoelastic fluids
proposed in a previous work (Int. J. Eng. Sci. 48 (2010), 1279–1288). As a
recapitulation of that work, the basic theory is presented in terms of the temporal
frequency and spatial wave number in the Laplace–Fourier domain. Taylor-series
expansions in these variables provides a weakly non-local theory in spatio-temporal
gradients that is more comprehensive than the “bi-velocity” model of Brenner. The
linearized Chapman–Enskog kinetic theory is shown to provide a confirmation of the
more general theory, from which one can reconstruct a fully non-local integral
model.
Following the work of Davis and Brenner (J. Acoust. Soc. Am. 132 (2012),
2963–2969), the general theory is employed to derive dispersion relations for acoustic,
thermal and shear-wave propagation in compressible viscoelastic fluids. At Burnett
order the Chapman–Enskog theory gives a cubic polynomial in wave number squared
which reduces in the dissipative quasi-static limit to a quadratic like that given by
the classical Navier–Stokes–Fourier model and the bi-velocity modification of that
model.
With minor modification, the present analysis applies to viscoelastic shear and
dilatational wave propagation in solids with higher-gradient and Cosserat
effects, where it may, for example, find application to the field of rotational
seismology.