The effect of random flow on solar acoustic waves

We examine the influence of a random flow that occurs in the convection zon e on frequencies of the solar acoustic oscillations. Using a perturbative m ethod the dispersion relation is derived in the case of a random flow that is parallel to the wave propagation. This relation is subsequently solved n umerically for various parameters of the random field to find the frequenci es of the random acoustic waves. The numerical results reveal that these wa ves can be both amplified and damped by the random flow: also their frequen cies can be higher and lower than the frequencies of the coherent acoustic waves. The amplification and frequency increase are more pronounced for low spherical harmonic degree l, stronger random flow, and lower spatial corre lation length, These analytical findings are tested against numerical simul ations for the full set of linear equations, without introducing a weak ran dom field approximation. Numerical results reveal for the first time wave a mplification and frequency decrease of the sound waves.