Water Supply Vol 2 No 5-6 pp 47–55 © IWA Publishing 2002
Analysis of local velocity gradients in rapid mixer using particle image velocimetry technique
N.-S. Park* and H. Park**
*Department of Civil Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea
**Department of Civil Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea
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 G-value 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.
Full article (PDF Format)
PAY-PER-VIEW: Buy this article for £20.00 (IWA MEMBER PRICE: £15.00)
|
