FEM simulation of a sono-reactor accounting for vibrations of the boundaries

Abstract

The chemical effects of acoustic cavitation are obtained in sono-reactors built-up from a vessel and an ultrasonic source. In this paper, simulations of an existing sono-reactor are carried out, using a linear acoustics model, accounting for the vibrations of the solid walls. The available frequency range of the generator (19 kHz-21 kHz) is systematically scanned. Global quantities are plotted as a function of frequency in order to obtain response curves, exhibiting several resonance peaks. The attenuation coefficient of the wave is taken as a variable parameter, in absence of the precise knowledge of the bubble size distribution, and its influence is studied. The concepts of acoustic energy, intensity and active power are recalled, along with the general balance equation for acoustic energy. The latter is used as a convergence check of the simulations. Finally, it is shown that the interface between the liquid and the solid walls cannot be correctly represented by the simple approximations of either infinitely soft, or infinitely hard boundaries. Moreover, the liquid-solid coupling allows the cooling jacket to receive a noticeable part of the input power, although it is not in direct contact with the sonotrode. It may therefore undergo cavitation and this feature opens the perspective to design sono-reactors which avoid direct contact between the working liquid and the sonotrode.

Numerical simulation of the nonlinear ultrasonic pressure wave propagation in a cavitating bubbly liquid inside a sonochemical reactor

“…Further, the zero flux boundary condition at the surfaces of the heaters and the sonoreactor include some basic assumptions. A comprehensive way to account for more realistic boundary conditions is the coupling of elastic deformation and the wave propagation as implemented succesfully in [48,49,50]. Finally, other numerical methods, such as, the finite element method (FEM), the boundary element method (BEM) or the finite volume method (FVM), may be employed to solve the Helmholtz equation in order to compare their convergence rates with the current numerical approach.…”

Guidelines for the design of efficient sono-microreactors

“…The acoustic field within the liquid microchannel and the deformation of the stacked microreactor have been calculated by following simulation strategies found in the literature [27,28].…”

Sonoelectrochemistry in Environmental Applications

“…A non-optimized flow sonoelectrochemical system was used for process scale-up ( Figure 4.2). In this work, the polypropylene sonoelectrochemical reactor was designed to be used in divided and undivided configurations, whereby the acoustic field in the reactor was calculated according to the finite-element simulation method [24,25].…”