A visualisation technique for quantifying mixing in stirred tank

A technique for quantifying the mixing evolution in a transparent stirred tank is proposed. It consists of capturing on video a colorisation-decolorisation process in a stirred vessel and apply the fundamentals of light absorption imaging technique in combination with image analysis. The advantages of the method developed are that 1) there is no disturbance of the fluid flow, 2) no preliminary calibration is necessary, 3) it allows to quantify the mixing evolution in the whole vessel. This paper describes protocols for carrying this method out. In addition examples of experimental results obtained for both a standard and a non standard geometrical mixing system are given and discussed. The results indicate that the technique has significant potential to provide insight to study and compare mixing efficiency of different impellers or mixing systems