Water Science and Engineering 2017, 10(3) 225-235 DOI:   https://doi.org/10.1016/j.wse.2017.09.003  ISSN: 1674-2370 CN: 32-1785/TV

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Keywords
Braided river
Critical criterion
Empirical formula
Flow pattern
Temperature distribution
Thermally stratified flow
Authors
PubMed

Flow patterns and critical criteria of thermally stratified shear flow in braided rivers

Li Gu a,b,*, Qiu-lan Li c, Bo Dai d, Zu-lin Hua b, Xiao-dong Liu e, Ke-jian Chu e

aDepartment of Civil and Environmental Engineering, University of Alberta, Edmonton T6G 2R3, Canada
bKey Laboratory of Integrated Regulation and Resource Development of Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, China
cZhenjiang Urban Planning and Design Institute, Zhenjiang 212000, China
dJiangsu Transportation Institute, Nanjing 210098, China
eNational Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety, Hohai University, Nanjing 210098, China

Abstract

Flow characteristics of thermally stratified shear flow in braided rivers are particularly complicated and poorly understood. In this study, a series of typical flow patterns was examined and their critical criteria were determined. Four flow patterns were identified: mixed, locally unstable, continuously stratified, and two-layer flow. Temperature distributions of the four types of flow patterns were analyzed and compared. The critical Froude numbers for unstable flow,  , and stable flow,  , were determined to be 6 and 1, respectively, and comparison of   and   to the peak Froude numbers,   at the outer bank and   at the inner bank along the anabranch, allowed the flow patterns to be assessed. Then, a discriminant based on initial Jeffreys-Keulegan stability parameters was established to distinguish the flow stages from two-layer flow to completely mixed flow. It is indicated that the three critical Jeffreys-Keulegan parameters increased with the diversion angle of braided rivers. Results also show that, compared to the stratified flow in straight and curved channels, it was more difficult for braided stratified flow to maintain as two-layer flow, and it more easily became mixed flow. Consequently, empirical expressions for stability criteria of the thermally stratified shear flow in braided rivers are presented.

Keywords Braided river   Critical criterion   Empirical formula   Flow pattern   Temperature distribution   Thermally stratified flow  
Received 2016-08-07 Revised 2017-05-12 Online: 2017-07-30 
DOI: https://doi.org/10.1016/j.wse.2017.09.003
Fund:

This work was supported by the National Natural Science Foundation of China (Grants No. 51379058, 51379060, and 51479064), the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD Project), and the Fundamental Research Funds for the Central Universities (Grants No. 2016B06714 and 2014B07814).

Corresponding Authors: guliqc@hhu.edu.cn (Li Gu).
Email: guliqc@hhu.edu.cn
About author:

References:

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