ABSTRACT
For compressible, adiabatic fluid, considering the loss of flow momentum, the equation of small amplitude motion is shown as below:
∂ ∂
+ = p x
f i fγ θ ρ x(x ) (+u )θ 0
(1)
where p = fluid overpressure; x = spatial coordinate; u f = fluid particle velocity; u f = is fluid particle acceleration; ρf = fluid density; γ = volume drag force (ratio of force and speed on per volume element); θi = field variable which is independent with fluid particle position but may be associated with ρf and γ.
