Numerical investigation of cavitation flows with inhomogeneous polydisperse bubble populations
* Presenting author
Abstract:
Acoustic cavitation induced by intense ultrasound allows to intensify a wide range of chemical reactions in process engineering. However, to fully exploit the potential of ultrasound, the geometries of reactors have to be adapted to the ultrasound field. This requires validated computational tools.A solver for acoustic cavitation is proposed in OpenFOAM, which predicts acoustic field inside a reactor taking into account damping effect of cavitation bubbles. We use an Euler-Lagrange approach to couple acoustics and flow with cavitation bubbles, where the first two are described as field quantities (Eulerian) and the latter as discrete particles (Lagrangian). The governing equation for acoustics is the Helmholtz equation which is coupled with a state-of-the-art cavitation damping model. The flow is described by the unsteady Reynolds-Averaged Navier-Stokes equations (URANS). The cavitation bubbles are coupled to the Eulerian phase by introducing primary Bjerknes force and momentum exchange with the surrounding liquid. The model allows efficient computation of cavitation flows with spatially inhomogeneous and polydisperse bubble distribution.Test cases focus primarily on reactors with immersed ultrasound transducers. We present results with monodisperse bubble populations, where the bubble diameter is altered keeping all other input parameters, especially the void fraction, constant. Further, polydisperse cases are discussed.