Analysis of local velocity gradients in rapid mixer using particle image velocimetry technique

Abstract

Recognizing the significance of factual velocity fields in a rapid mixer, this study focuses on

analyzing local velocity gradients in various mixer geometries with particle image velocimetry (PIV) and

comparing the results of the analysis with the conventional G-value, for reviewing the roles of G-value in the

current design and operation practices. The results of this study clearly show that many arguments and

doubts are possible about the scientific correctness of G-value, and its current use. This is because the Gvalue

attempts to represent the turbulent and complicated factual velocity field in a jar. Also, the results

suggest that it is still a good index for representing some aspects of mixing condition, at least, mixing

intensity. However, it cannot represent the distribution of velocity gradients in a jar, which is an important

factor for mixing. This study as a result suggests developing another index for representing the distribution to

be used with the G-value.