The main design objective for bubble columns is efficient mixing, which is strongly influenced by the dispersed phase. Mixing efficiency can be measured in a number of ways. One example is to measure the gas hold-up in the riser as a function of the superficial gas velocity. This would require solving for the gas volume fraction for a number of simulations, each with a different mass flow rate of the dispersed phase at the sparger. Another option would be to use the same input parameters, this time measuring the liquid velocity in the downcomer.