The conventional fluid description of multi-component plasma, supplemented by
an appropriate equation of state for the macroparticle component, is used to
evaluate the longitudinal sound velocity of Yukawa fluids. The obtained results
are in very good agreement with those obtained earlier employing the
quasi-localized charge approximation and molecular dynamics simulations in a
rather broad parameter regime. Thus, a simple yet accurate tool to estimate the
sound velocity across coupling regimes is proposed, which can be particularly
helpful in estimating the dust-acoustic velocity in strongly coupled dusty
(complex) plasmas. It is shown that, within the present approach, the sound
velocity is completely determined by particle-particle correlations and the
neutralizing medium (plasma), apart from providing screening of the Coulomb
interaction, has no other effect on the sound propagation. The ratio of the
actual sound velocity to its "ideal gas" (weak coupling) scale only weakly
depends on the coupling strength in the fluid regime, but exhibits a pronounced
decrease with the increase of the screening strength. The limitations of the
present approach in applications to real complex plasmas are briefly discussed.Comment: Physical Review E (in press
