(426a) Towards an Understanding of Fluid and Particle History in a Turbulent Mixing Tank Using Large Eddy Simulation: Examining Effect of Different Impeller Types.

Prior work has shown the differences in energy dissipation zones in different portions of the vessel, e.g. in the trailing vortex, far from the impeller, etc. The path that the fluid or particle takes between these zones is difficult to measure experimentally. Computational Fluid Dynamics is an attractive approach to directly predict the path of the fluid or particles in the system and measure the history of exposure to the differing energy dissipation regimes. In particular, the large eddy simulation model is particularly suited for describing the random transient behaviors inside a fully turbulent tank.

Following previous work [1], we will present the time history of energy-dissipation in mixing tanks across multiple scales using the LES model. We will extend the prior work by extending the range of systems studied including changing pumping direction and impeller types.

First, the time-averaged energy-dissipation predictions will be compared to literature reported values, and the accuracy and limitations of the LES modelling approach will be discussed. The energy dissipation history can be filtered through signal processing operations that leads to an understanding of power being applied to the fluid at different scales. We will show that there are fundamental relationships that collapse the time history information onto a universal curve. We will show the effect of changing the system beyond a geometrical scale up, including by varying impeller type.

[1] Flamm, Raudenbush, Sirota, Cote. AICHE Annual Meeting 2019.