Guided waves in a moving layer of fluid between two elastic solids

We consider the motion of compressible fluid in a channel between two infinite elastic layers with the same properties (homogeneous and isotropic). We suppose that the layer of fluid moves with a constant velocity, respectively, to the other layers. Under certain conditions the moving layer can function as a waveguide. The aim is to determine necessary conditions for the existence of a running wave along the channel and a standing wave in a transversal direction when the channel functions as a waveguide.