The effect of increasing the stirrer speed in an unbaffled stirred tank reactor is that

• a small increase in stirrer speed will cause the liquid to enter the turbulent flow regime
• as the stirrer speed increases, the liquid will continue to circulate and then become turbulent
• as the stirrer speed increases, the liquid will continue to circulate. Eventually a vortex will form.
• A vortex will form at low stirrer speeds. As the stirrer speed increases the liquid will start to circulate