23. Numerical Modeling of Vibration Induced Atomization of Liquids

The numerical modeling of vibration induced atomization of liquids validates existing operating parameters of known systems. A computational fluid dynamics analysis is performed which assists in model verification and reveals a critical configuration of driving amplitude and liquid depth that must be fulfilled for atomization. In this configuration the droplet kinetic energy exceeds the fluid resistance energy and the atomization process initiates. Verification and identification of the parameters for atomization of a thin film of water is accomplished.

Existing literature on the operation of vibrating mesh nebulizers does not entirely explain the principles by which these devices atomize liquids. Many previous studies assume a spray or extrusion mode of droplet generation, but it can be demonstrated that the high frequency vibration of these devices is sufficient to produce aerosol droplets. A thin film of liquid vibrated under the correct conditions will produce a fountain of atomized liquid droplets. The formation of standing waves on the surface of a thin film have an oscillating frequency that is half the driving frequency, a wavelength that is equal to a function of the driving frequency, a mean droplet diameter one-third the standing wavelength dimension, and are also dependent of fluid density and interfacial surface tension.