Furthermore in case of a polydisperse air water or water steam bubbly flow the bubble size distribution, bubble break-up and coalescence processes as well as different gas velocities in dependency on the bubble diameter are taken into account in the newly developed inhomogeneous MUSIG model.
New kernel functions for the rate of bubble break-up and coalescence are presented.
A bubble number density equation is implemented in order to account for the combined effect of bubble break-up and coalescence in the tank.
As for the bubble dimensions modelling, besides the mono-dispersed assumption, a population balance method, named MUSIG, with bubble break-up and coalescence models is considered.
The bubble break-up and coalescence were considered in gas liquid dispersion whereas in the foam layer, the bubble coalescence due to film rupture was incorporated.
The Sγ model, based on the moments of the bubble size distribution, tracks the evolution of the bubble sizes due to bubble break-up and bubble coalescence.
A model parameter study for bubble break-up and coalescence is performed to find the optimum values of the model parameters, i.e. the critical Weber number and the coalescence calibration factor.
Agreement may be improved with advances in the treatment of large bubbles and bubble break-up and coalescence, as well as in improved modelling of the boiling region close to the wall, and more specifically the bubble departure diameter, the wall treatment and the contribution of bubbles to turbulence.
We study the influence of the three primary sources leading to the uneven distribution of bubbles: (1) nonuniformity in the size of bubbles fed to the distributor, (2) lack of bubble break-up, and (3) asymmetric bubble breakup caused by asymmetries in flow due to fabrication tolerances.
The relative bubble break up performance of the two impellers are compared in terms of measured local rates of energy dissipation and turbulent kinetic energy in the impeller zone.
