High frequency linear response of classical fluids

We investigate the asymptotic high frequency properties of the complex transport coefficients of a classical fluid in the long wavelength limit. Subject to assumptions corresponding essentially to the infinite differentiability intermolecular forces for real fluids we show that as $\mathrm{\omega }\to \infty$ the linear response of a classical fluid to a bulk periodic force is nondissipative. We investigate the effective order of magnitude of $\mathrm{\omega }$ in order that such a response can be elucidated and diffusional, stress and temperature waves be observed. We conclude with a brief discussion of how these results must be modified for certain nondifferentiable intermolecular forces which arise in simplified statistical models of fluids.