Propagation of normal waves in porous rod with opened pores on boundaries

Propagation of normal waves in porous cylindrical rod with opened pores on boundaries is investigated. For this medium the dispersion equation is derived. At low-frequency this equation has one root which is velocity of a normal wave. While in the case of porous rod with closed pores there are two low-frequency waves. At high-frequency the dispersion equation can have in specific parameters one root. With such velocity the Rayleigh wave propagates along free boundary of porous medium with opened pores. The indicated root can be absent. In this case the Rayleigh wave is absent.