Effect of vegetation on flow hydraulics in compound open channels with non-prismatic floodplains
The present paper aims to evaluate the effect of emergent rigid vegetation density on the flow's turbulence structure and hydraulic parameters at the non-prismatic floodplains. The experiments were performed using the physical model of the asymmetric non-prismatic compound channel. The results...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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IWA Publishing
2023-05-01
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| Series: | Aqua |
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| Online Access: | http://aqua.iwaponline.com/content/72/5/781 |
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| author | A. Samadi Rahim Hojjat Allah Yonesi H. R. Rahimi B. Shahinejad H. Torabi Podeh Hazi Mohammad Azamathulla |
| author_facet | A. Samadi Rahim Hojjat Allah Yonesi H. R. Rahimi B. Shahinejad H. Torabi Podeh Hazi Mohammad Azamathulla |
| author_sort | A. Samadi Rahim |
| collection | DOAJ |
| description | The present paper aims to evaluate the effect of emergent rigid vegetation density on the flow's turbulence structure and hydraulic parameters at the non-prismatic floodplains. The experiments were performed using the physical model of the asymmetric non-prismatic compound channel. The results show that the velocity distribution in the vegetation flow is more influenced by the drag force caused by the vegetation than by the bed shear stress and does not follow the law of logarithmic velocity distribution throughout the non-prismatic section. The intense velocity gradient at the interface of the main channel and the floodplain leads to the development of strong secondary currents, increased Reynolds shear stresses, apparent shear stresses and momentum exchange in this region. Vegetation also decreases mean kinetic energy in the floodplain and increases it in the main channel. The mean turbulence exchange coefficient for the non-prismatic compound channels without vegetation was 0.23 and for the divergent and convergent compound channels was 0.035 and 0.020, respectively. The comparison of the local drag coefficient results shows that the fluctuations of this parameter are greater in the divergent section than in the convergent section due to the strong secondary currents in the interface.
HIGHLIGHTS
This paper is the result of original research in the field of river engineering.;
Its innovation is in the field of compound open channel and flow turbulence structure.;
The Acoustic Doppler Velocimeter (ADV) profiler has been used with high accuracy to understand the flow structure.;
Vegetation on flood plains and its effects on flow hydraulic is novel.;
Comparison has been made between the effects of divergence and convergence on flow hydraulics.; |
| first_indexed | 2024-03-13T07:06:03Z |
| format | Article |
| id | doaj.art-fa9ef923f9954663bebe31ab9e94fb5e |
| institution | Directory Open Access Journal |
| issn | 2709-8028 2709-8036 |
| language | English |
| last_indexed | 2024-03-13T07:06:03Z |
| publishDate | 2023-05-01 |
| publisher | IWA Publishing |
| record_format | Article |
| series | Aqua |
| spelling | doaj.art-fa9ef923f9954663bebe31ab9e94fb5e2023-06-06T11:32:11ZengIWA PublishingAqua2709-80282709-80362023-05-0172578179710.2166/aqua.2023.043043Effect of vegetation on flow hydraulics in compound open channels with non-prismatic floodplainsA. Samadi Rahim0Hojjat Allah Yonesi1H. R. Rahimi2B. Shahinejad3H. Torabi Podeh4Hazi Mohammad Azamathulla5 Department of Water Engineering, Lorestan University, Khorramabad, Iran Department of Water Engineering, Lorestan University, Khorramabad, Iran Department of Civil Engineering, Xi'an Jiaotong-Liverpool University, Suzhou, China Department of Water Engineering, Lorestan University, Khorramabad, Iran Department of Water Engineering, Lorestan University, Khorramabad, Iran Department of Civil Engineering, The University of the West Indies, St Augustine, Trinidad The present paper aims to evaluate the effect of emergent rigid vegetation density on the flow's turbulence structure and hydraulic parameters at the non-prismatic floodplains. The experiments were performed using the physical model of the asymmetric non-prismatic compound channel. The results show that the velocity distribution in the vegetation flow is more influenced by the drag force caused by the vegetation than by the bed shear stress and does not follow the law of logarithmic velocity distribution throughout the non-prismatic section. The intense velocity gradient at the interface of the main channel and the floodplain leads to the development of strong secondary currents, increased Reynolds shear stresses, apparent shear stresses and momentum exchange in this region. Vegetation also decreases mean kinetic energy in the floodplain and increases it in the main channel. The mean turbulence exchange coefficient for the non-prismatic compound channels without vegetation was 0.23 and for the divergent and convergent compound channels was 0.035 and 0.020, respectively. The comparison of the local drag coefficient results shows that the fluctuations of this parameter are greater in the divergent section than in the convergent section due to the strong secondary currents in the interface. HIGHLIGHTS This paper is the result of original research in the field of river engineering.; Its innovation is in the field of compound open channel and flow turbulence structure.; The Acoustic Doppler Velocimeter (ADV) profiler has been used with high accuracy to understand the flow structure.; Vegetation on flood plains and its effects on flow hydraulic is novel.; Comparison has been made between the effects of divergence and convergence on flow hydraulics.;http://aqua.iwaponline.com/content/72/5/781momentum exchangenon-prismatic compound channelssecondary currentturbulence structurevegetation density |
| spellingShingle | A. Samadi Rahim Hojjat Allah Yonesi H. R. Rahimi B. Shahinejad H. Torabi Podeh Hazi Mohammad Azamathulla Effect of vegetation on flow hydraulics in compound open channels with non-prismatic floodplains Aqua momentum exchange non-prismatic compound channels secondary current turbulence structure vegetation density |
| title | Effect of vegetation on flow hydraulics in compound open channels with non-prismatic floodplains |
| title_full | Effect of vegetation on flow hydraulics in compound open channels with non-prismatic floodplains |
| title_fullStr | Effect of vegetation on flow hydraulics in compound open channels with non-prismatic floodplains |
| title_full_unstemmed | Effect of vegetation on flow hydraulics in compound open channels with non-prismatic floodplains |
| title_short | Effect of vegetation on flow hydraulics in compound open channels with non-prismatic floodplains |
| title_sort | effect of vegetation on flow hydraulics in compound open channels with non prismatic floodplains |
| topic | momentum exchange non-prismatic compound channels secondary current turbulence structure vegetation density |
| url | http://aqua.iwaponline.com/content/72/5/781 |
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