# Representative industrial aerated stirred tank reactor

Representative industrial case for simulating an aerated stirred tank operating
with air as the gaseous phase and water as the liquid phase. The tank is baffled
and the stirrer features a pitch-blade impeller at the top and a Rushton turbine
at the bottom. The geometric ratios adhere to the recommendations given by
Middleton & Smith [^1], making the flow regime map published therein applicable.

The setup was tested for various combinations rotational speeds and gas flow
rates, which demonstrated the following flow regimes:

| Regime                                                    | rpm | m^3/min |
| --------------------------------------------------------- | --- | ------- |
| Fully flooded stirrer, no dispersion                      | 100 | 0.37    |
| Gas dispersed in upper part, small gas cavities at blades | 200 | 0.15    |
| Gas dispersed in upper part, large gas cavities           | 200 | 0.75    |
| Complete dispersion, small gas cavities                   | 500 | 0.37    |
| Complete dispersion, large gas cavities                   | 500 | 1.12    |

The case uses a combination of the semi-implicit MULES algorithm with
sub-cycling to solve the phase fraction transport equation at the high maximum
Courant number of 40, which enables the solution to evolve quickly to a
steady-state.  It is possible to maintain a stable and accurate solution at such
a high maximum Courant number because the regions of high velocity are localised
around the sparger and blade tips while the mean Courant number is less than
~0.7.

[^1]: Middleton, J. C., & Smith, J. M. (2004). Gas–Liquid Mixing in Turbulent
    Systems. In: Paul E.L., Atiemo- Obeng V.A., Kresta S.M. (Eds.). Handbook of
    industrial mixing. John Wiley & Sons Inc.
