Studying the Wake of an Island in a Macro-Tidal Estuary
Tidal flow can generate unsteady wakes, large eddies, and recirculation zones in the lee or around complex natural and artificial obstructions, such as islands, headlands, or harbours. It is essential to understand the flow patterns around such structures given the potential impacts they can have on...
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2020-04-01
|
| Series: | Water |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2073-4441/12/5/1225 |
| _version_ | 1797569639564181504 |
|---|---|
| author | Bin Guo Reza Ahmadian Paul Evans Roger A. Falconer |
| author_facet | Bin Guo Reza Ahmadian Paul Evans Roger A. Falconer |
| author_sort | Bin Guo |
| collection | DOAJ |
| description | Tidal flow can generate unsteady wakes, large eddies, and recirculation zones in the lee or around complex natural and artificial obstructions, such as islands, headlands, or harbours. It is essential to understand the flow patterns around such structures given the potential impacts they can have on sedimentation, the marine environment, ecology, and anthropogenic activities. In this paper, the wake around an island in a macro-tidal environment has been studied using a widely used hydro-environmental model, Telemac-2D. Current data collected using moored acoustic Doppler current profilers (ADCPs) were used to validate and refine the Telemac-2D model. Four different turbulence models and several different solver options for the k-<inline-formula> <math display="inline"> <semantics> <mi mathvariant="sans-serif">ε</mi> </semantics> </math> </inline-formula> model were tested in this study to assess which representation could best replicate the hydrodynamics. The classic k-<inline-formula> <math display="inline"> <semantics> <mi mathvariant="sans-serif">ε</mi> </semantics> </math> </inline-formula> model with the solver of conjugate residual was the most suitable method to simulate the wake in the lee of the island. The model results showed good correlation with measured data. The island wake parameter used to predict the wake behaviour and its predictions matched the model results for different tidal conditions, suggesting that the island wake parameter could be used to predict the wake behind obstacles in macro-tidal environments. The model predictions showed the development of a wake is similar between ebb and flood tides in the neap tide while showing more difference in spring tide. With the increase of velocity in the neap tide, two side-by-side vortices will appear and then changing to stable Karman Vortex Street. During the ebb phase of spring tide, the wake will develop from a stable vortex to an unstable Karman Vortex Street, while the wake remained stable with two vortices during an flood tide. |
| first_indexed | 2024-03-10T20:14:29Z |
| format | Article |
| id | doaj.art-635b53988c074c79947dd3cddfbac989 |
| institution | Directory Open Access Journal |
| issn | 2073-4441 |
| language | English |
| last_indexed | 2024-03-10T20:14:29Z |
| publishDate | 2020-04-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Water |
| spelling | doaj.art-635b53988c074c79947dd3cddfbac9892023-11-19T22:41:16ZengMDPI AGWater2073-44412020-04-01125122510.3390/w12051225Studying the Wake of an Island in a Macro-Tidal EstuaryBin Guo0Reza Ahmadian1Paul Evans2Roger A. Falconer3Hydro-Environmental Research Centre, School of Engineering, Cardiff University, Cardiff CF24 3AA, UKHydro-Environmental Research Centre, School of Engineering, Cardiff University, Cardiff CF24 3AA, UKIntertek Water and Energy Ltd., The Maltings, East Tyndall Street, Cardiff CF24 5EA, UKHydro-Environmental Research Centre, School of Engineering, Cardiff University, Cardiff CF24 3AA, UKTidal flow can generate unsteady wakes, large eddies, and recirculation zones in the lee or around complex natural and artificial obstructions, such as islands, headlands, or harbours. It is essential to understand the flow patterns around such structures given the potential impacts they can have on sedimentation, the marine environment, ecology, and anthropogenic activities. In this paper, the wake around an island in a macro-tidal environment has been studied using a widely used hydro-environmental model, Telemac-2D. Current data collected using moored acoustic Doppler current profilers (ADCPs) were used to validate and refine the Telemac-2D model. Four different turbulence models and several different solver options for the k-<inline-formula> <math display="inline"> <semantics> <mi mathvariant="sans-serif">ε</mi> </semantics> </math> </inline-formula> model were tested in this study to assess which representation could best replicate the hydrodynamics. The classic k-<inline-formula> <math display="inline"> <semantics> <mi mathvariant="sans-serif">ε</mi> </semantics> </math> </inline-formula> model with the solver of conjugate residual was the most suitable method to simulate the wake in the lee of the island. The model results showed good correlation with measured data. The island wake parameter used to predict the wake behaviour and its predictions matched the model results for different tidal conditions, suggesting that the island wake parameter could be used to predict the wake behind obstacles in macro-tidal environments. The model predictions showed the development of a wake is similar between ebb and flood tides in the neap tide while showing more difference in spring tide. With the increase of velocity in the neap tide, two side-by-side vortices will appear and then changing to stable Karman Vortex Street. During the ebb phase of spring tide, the wake will develop from a stable vortex to an unstable Karman Vortex Street, while the wake remained stable with two vortices during an flood tide.https://www.mdpi.com/2073-4441/12/5/1225island wakeTelemac-2Dturbulence modelSevern EstuaryADCPsvortices |
| spellingShingle | Bin Guo Reza Ahmadian Paul Evans Roger A. Falconer Studying the Wake of an Island in a Macro-Tidal Estuary Water island wake Telemac-2D turbulence model Severn Estuary ADCPs vortices |
| title | Studying the Wake of an Island in a Macro-Tidal Estuary |
| title_full | Studying the Wake of an Island in a Macro-Tidal Estuary |
| title_fullStr | Studying the Wake of an Island in a Macro-Tidal Estuary |
| title_full_unstemmed | Studying the Wake of an Island in a Macro-Tidal Estuary |
| title_short | Studying the Wake of an Island in a Macro-Tidal Estuary |
| title_sort | studying the wake of an island in a macro tidal estuary |
| topic | island wake Telemac-2D turbulence model Severn Estuary ADCPs vortices |
| url | https://www.mdpi.com/2073-4441/12/5/1225 |
| work_keys_str_mv | AT binguo studyingthewakeofanislandinamacrotidalestuary AT rezaahmadian studyingthewakeofanislandinamacrotidalestuary AT paulevans studyingthewakeofanislandinamacrotidalestuary AT rogerafalconer studyingthewakeofanislandinamacrotidalestuary |