Numerical modelling of effects of ultrasound-induced acoustic streaming on hydrodynamics in a confined impinging jet reactor using a non-linear model based on local velocity fluctuation

This paper aims to propose and demonstrate a model accounting for the influence of acoustic streaming generated by ultrasound wave propagation on hydrodynamics in a confined impinging jet reactor. It was derived based on the Navier-Stokes equations. Villermaux-Dushman reaction system was also coupled with the CFD modelling developed to mimic the effects of ultrasound acoustic streaming on the micro-mixing performance. The numerical results were validated experimentally. The modelling results have clearly shown that the inten-sification effects of ultrasound acoustic streaming on the turbulent dissipation rate and micro-mixing perfor-mance can be well predicted by the model proposed with an empirical parameter. Micro-scale eddies were observed as a "Reynolds-averaged" influence of acoustic streaming on the velocity field in the impinging zone at a relatively low inlet Reynolds number. The instantaneous impact of acoustic streaming on the turbulent kinetic energy and dissipation rate was found to be dominated by the instantaneous velocity fluctuation in the reactor. The results obtained in the present study clearly indicated that the proposed model may be used as a cost-effective alternative to predict the intensification effects of ultrasound acoustic streaming on the hydrody-namics and micro-mixing performance in a confined impinging jet reactor.