f0 58[kHz] Driving frequency c0 343[m/s] Speed of sound lambda0 c0/f0 Wavelength Dt 2*lambda0 Transducer diameter Dr 3*lambda0 Reflector diameter H 5*lambda0/2 Height dvisc 0.22[mm]*sqrt(100[Hz]/f0) Viscous boundary layer thickness d_p lambda0/10 Particle diameter rho_p 500[kg/m^3] Particle density rho_f 1.2[kg/m^3] Fluid density (air) mu_f 1.8e-5[Pa*s] Fluid viscosity (air) a0 1.5e6[m/s^2] Normal acceleration of transducer