some reasons why I  simulate this problem :

The Importance of Gas-Liquid Mixing

Gas-liquid contacting process were play an important roles in industrial process such as fermentation, Wastewater treatments, hidrogenation process etc. 

Lack of experiments on gas liquid using Axial Flow impeller

Until late of 1990's, people believe that contacting gas-liquid can be effectively done using Rushton Disk turbine (radial flow pattern). 

An experiment said that by operating in pumping upward mode, axial flow impeller give the best result on dispersed gas in liquid body.

Check out AICHE Conferences 2000 with title "Power Characteristics of Gas-Liquid Mixing with wide blade up-pumping axial flow impellers in high viscosity CMC solution"

There's Software to play with 

Using this software, although rather painful, it gives cheaper and much less time to get the same result like experimentals does. And we don't have LDV or LDA equipment to perform it.