The effects of different turbulence models on modelling swirling flow in a macro-scale multi-inlet vortex reactor using transient solver

One of the methods used for the production of multiphase flow is the Flash NanoPrecipitation achievable by the usage of macro-size Multi-Inlet Vortex Reactor (MIVR). Previous studies showed that steady-state solvers such as the standard Reynolds Averaged Navier-Stokes (RANS) weren’t the most appropriate solvers for the simulation of a MIVR flow as it wasn’t capturing many highly temporal-fluctuating quantities. For example, the time-fluctuating formation of small vortices through the reactors flow [1] or even the wandering motion of the center of the core vortex in the mixing chamber [2] indicates that transient solvers can be promising for a more accurate simulation of the swirling flow and turbulent mixing taking place in a macro-MIVR. The study presented here take a comparative look on the solving of two different inlet Re flows in a macro-MIVR using a transient solver. This transient solver will essentially solve the cases using 4 different turbulence models: the SSG (Speziale Sarkar and Gatski), standard k-ε, LRR (Launder, Reece and Rodi) and SST k-ω models. The comparison of the results will be made by the analysis of the statistical information concerning the distribution of the passive scalar and the turbulent mixing provided by the probability density function (PDF) [3]. The comparison will also be made on the basis of experimental unconditional mean velocity extracted by using stereo-PIV and PLIF.

[1]E. Hitimana, R. O. Fox and J. C. Hill, Coherent structure characteristics of the swirling flow during turbulent mixing in a multi-inlet vortex reactor, Physics of Fluid 33, 065119 , 2021.

[2]Z. Liu, M. Ramezani, R. O. Fox, J. C. Hill and M. G. Olsen, Flow Characteristics in a Scaled-up Multi-inlet Vortex Nanoprecipitation Reactor, I&EC Research 54, pp. 4512-4525, 2015.

[3]E. Madadi-Kandjani, R. O. Fox and A. Passalacqua, Application of the Fokker-Planck molecular mixing model to turbulent scalar mixing using moment methods, Physics of fluids 29, 065109, 2017.