Numerical investigation of nonlinear interaction between salinity- and sediment-induced stratification in highly turbid estuaries and coastal seas

In highly turbid estuaries and coastal seas where freshwater rivers meet the salty ocean, both salinity-induced stratification (SaIS) and sediment-induced stratification (SeIS) are crucial in shaping total estuarine stratification. This study investigates the nonlinearity emerging from the interacti...

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Main Authors: Jian Zhou, Bing Sun, Huiming Zhang, Saiyu Yuan, Hongwu Tang
Format: Article
Language:English
Published: Taylor & Francis Group 2025-12-01
Series:Engineering Applications of Computational Fluid Mechanics
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Online Access:https://www.tandfonline.com/doi/10.1080/19942060.2024.2443123
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author Jian Zhou
Bing Sun
Huiming Zhang
Saiyu Yuan
Hongwu Tang
author_facet Jian Zhou
Bing Sun
Huiming Zhang
Saiyu Yuan
Hongwu Tang
author_sort Jian Zhou
collection DOAJ
description In highly turbid estuaries and coastal seas where freshwater rivers meet the salty ocean, both salinity-induced stratification (SaIS) and sediment-induced stratification (SeIS) are crucial in shaping total estuarine stratification. This study investigates the nonlinearity emerging from the interaction between SaIS and SeIS using a one-dimensional water column model over an erodible bed, driven by a longitudinal salinity gradient and oscillating tidal currents. The results reveal that total stratification deviates significantly from a simple addition of SaIS under clearwater conditions and SeIS under freshwater conditions, indicating a highly nonlinear interaction. The complex spatial and temporal patterns of the nonlinearity arise from the differing source-sink dynamics of salt and sediment. SaIS reduces SeIS during flood but intensifies it during ebb, whereas SeIS consistently strengthens SaIS. This nonlinearity, which exhibits notable flood-ebb asymmetry, is relatively insensitive to changes in tidal forcing compared to salinity gradient forcing, due to the conflicting effects of tidal currents on salinity straining, sediment diffusion, and turbulent mixing. These findings highlight the necessity of incorporating sediment's modulation of classical strain-induced periodic stratification due to salinity gradients in numerical models to improve predictions of buoyancy and stability in highly turbid estuarine and coastal systems.
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spelling doaj-art-992a4b4f0115460ab3919a13cfafc03f2025-08-20T02:52:42ZengTaylor & Francis GroupEngineering Applications of Computational Fluid Mechanics1994-20601997-003X2025-12-0119110.1080/19942060.2024.2443123Numerical investigation of nonlinear interaction between salinity- and sediment-induced stratification in highly turbid estuaries and coastal seasJian Zhou0Bing Sun1Huiming Zhang2Saiyu Yuan3Hongwu Tang4National Key Laboratory of Water Disaster Prevention, Hohai University, Nanjing, People's Republic of ChinaNational Key Laboratory of Water Disaster Prevention, Hohai University, Nanjing, People's Republic of ChinaNational Key Laboratory of Water Disaster Prevention, Hohai University, Nanjing, People's Republic of ChinaNational Key Laboratory of Water Disaster Prevention, Hohai University, Nanjing, People's Republic of ChinaNational Key Laboratory of Water Disaster Prevention, Hohai University, Nanjing, People's Republic of ChinaIn highly turbid estuaries and coastal seas where freshwater rivers meet the salty ocean, both salinity-induced stratification (SaIS) and sediment-induced stratification (SeIS) are crucial in shaping total estuarine stratification. This study investigates the nonlinearity emerging from the interaction between SaIS and SeIS using a one-dimensional water column model over an erodible bed, driven by a longitudinal salinity gradient and oscillating tidal currents. The results reveal that total stratification deviates significantly from a simple addition of SaIS under clearwater conditions and SeIS under freshwater conditions, indicating a highly nonlinear interaction. The complex spatial and temporal patterns of the nonlinearity arise from the differing source-sink dynamics of salt and sediment. SaIS reduces SeIS during flood but intensifies it during ebb, whereas SeIS consistently strengthens SaIS. This nonlinearity, which exhibits notable flood-ebb asymmetry, is relatively insensitive to changes in tidal forcing compared to salinity gradient forcing, due to the conflicting effects of tidal currents on salinity straining, sediment diffusion, and turbulent mixing. These findings highlight the necessity of incorporating sediment's modulation of classical strain-induced periodic stratification due to salinity gradients in numerical models to improve predictions of buoyancy and stability in highly turbid estuarine and coastal systems.https://www.tandfonline.com/doi/10.1080/19942060.2024.2443123Highly turbid estuariesestuarine hydrodynamicssalinity-induced stratificationsediment-induced stratificationnumerical investigation
spellingShingle Jian Zhou
Bing Sun
Huiming Zhang
Saiyu Yuan
Hongwu Tang
Numerical investigation of nonlinear interaction between salinity- and sediment-induced stratification in highly turbid estuaries and coastal seas
Engineering Applications of Computational Fluid Mechanics
Highly turbid estuaries
estuarine hydrodynamics
salinity-induced stratification
sediment-induced stratification
numerical investigation
title Numerical investigation of nonlinear interaction between salinity- and sediment-induced stratification in highly turbid estuaries and coastal seas
title_full Numerical investigation of nonlinear interaction between salinity- and sediment-induced stratification in highly turbid estuaries and coastal seas
title_fullStr Numerical investigation of nonlinear interaction between salinity- and sediment-induced stratification in highly turbid estuaries and coastal seas
title_full_unstemmed Numerical investigation of nonlinear interaction between salinity- and sediment-induced stratification in highly turbid estuaries and coastal seas
title_short Numerical investigation of nonlinear interaction between salinity- and sediment-induced stratification in highly turbid estuaries and coastal seas
title_sort numerical investigation of nonlinear interaction between salinity and sediment induced stratification in highly turbid estuaries and coastal seas
topic Highly turbid estuaries
estuarine hydrodynamics
salinity-induced stratification
sediment-induced stratification
numerical investigation
url https://www.tandfonline.com/doi/10.1080/19942060.2024.2443123
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