Propagation of Shear Horizontal Acoustic Waves in a Quartz Plate with a Fluid Layer for Liquid Sensor Application

We study the propagation of shear horizontal (SH) acoustic waves in a quartz elastic plate in contact with a viscous fluid layer of a finite thickness as an acoustic wave sensor for measuring fluid viscosity or density. The first order elastic plate theory by Mindlin and the theory of Newtonian fluids are used. An equation for determining the dispersion relations of the SH waves is obtained. Approximate dispersion relations for long waves are given analytically. Numerical results showing the effects of the fluid on SH wave characteristics are presented.