A modeling study of the impact of major storms on seabed shear stress and sediment transport on the Grand Banks of Newfoundland

2017 ◽  
Vol 122 (5) ◽  
pp. 4183-4216 ◽  
Author(s):  
Michael Z. Li ◽  
Yongsheng Wu ◽  
Guoqi Han ◽  
Robert H. Prescott ◽  
Charles C. L. Tang
Keyword(s):  
Shear Stress ◽  
Sediment Transport ◽  
Grand Banks ◽  
The Impact ◽  
Modeling Study

scholarly journals A Numerical Study of Sheet Flow Driven by Skewed-Asymmetric Shoaling Waves Using SedWaveFoam

2021 ◽  
Vol 9 (9) ◽  
pp. 936
Author(s):  
Yeulwoo Kim ◽  
Ryan S. Mieras ◽  
Dylan Anderson ◽  
Timu Gallien
Keyword(s):  
Boundary Layer ◽  
Shear Stress ◽  
Sediment Transport ◽  
Transport Rate ◽  
Phase Lag ◽  
Bed Shear Stress ◽  
Sheet Flow ◽  
Sediment Transport Rate ◽  
Wave Conditions ◽  
The Impact

SedWaveFoam, an OpenFOAM-based two-phase model that concurrently resolves the free surface wave field, and the bottom boundary layer is used to investigate sediment transport throughout the entire water column. The numerical model was validated with large-scale wave flume data for sheet flow driven by shoaling skewed-asymmetric waves with two different grain sizes. Newly obtained model results were combined with previous nonbreaking and near-breaking wave cases to develop parameterization methods for time-dependent bed shear stress and sediment transport rate under various sediment sizes and wave conditions. Gonzalez-Rodriguez and Madsen (GRM07) and quasi-steady approaches were compared for intra-wave bed shear stress. The results show that in strongly asymmetric flows, considering the separated boundary layer development processes at each half wave-cycle (i.e., GRM07) is essential to accurately estimating bed shear stress and highlights the impact of phase-lag effects on sediment transport rates. The quasi-steady approach underpredicts (∼60%) sediment transport rates, especially for fine grains under large velocity asymmetry. A modified phase-lag parameter, incorporating velocity asymmetry, sediment stirring, and settling processes is proposed to extend the Meyer-Peter and Mueller type power law formula. The extended formula accurately estimated the enhanced net onshore sediment transport rate observed under skewed-asymmetric wave conditions.

scholarly journals A modeling study of the impact of major storms on waves, surface and near-bed currents on the Grand Banks of Newfoundland

2015 ◽  
Vol 120 (8) ◽  
pp. 5358-5386 ◽  
Author(s):  
Michael Z. Li ◽  
Yongsheng Wu ◽  
Robert H. Prescott ◽  
Charles C. L. Tang ◽  
Guoqi Han
Keyword(s):  
Grand Banks ◽  
The Impact ◽  
Modeling Study

P3588The synergistic effect of NIRS-detected lipid-rich plaque and 5 different multidirectional wall shear stress metrics on human coronary plaque growth

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
E M J Hartman ◽  
A M Kok ◽  
A Hoogendoorn ◽  
F J H Gijsen ◽  
A F W Steen ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Synergistic Effect ◽  
Coronary Arteries ◽  
Wall Thickness ◽  
Plaque Progression ◽  
Lipid Rich Plaque ◽  
Plaque Growth ◽  
Wall Shear ◽  
The Impact

Abstract Introduction Local wall shear stress (WSS) metrics, high local lipid levels (as detected by near-infrared spectroscopy (NIRS)), as well as systemic lipid levels, have been individually associated with atherosclerotic disease progression. However, a possible synergistic effect remains to be elucidated. This study is the first study to combine WSS metrics with NIRS-detected local lipid content to investigate a potential synergistic effect on plaque progression in human coronary arteries. Methods The IMPACT study is a prospective, single centre study investigating the relation between atherosclerotic plaque progression and WSS in human coronary arteries. Patients with ACS treated with PCI were included. At baseline and after 1-year follow-up, patients underwent near-infrared spectroscopy intravascular ultrasound (NIRS-IVUS) imaging and intravascular doppler flow measurements of at least one non-culprit coronary artery. After one month, a CT angiography was made. CT derived centreline combined with IVUS lumen contours resulted in a 3D reconstruction of the vessel. The following WSS metrics were computed using computational fluid dynamics applying the vessel specific invasive flow measurements: time-average wall shear stress (TAWSS), relative residence time (RRT), cross-flow index, oscillatory shear index and transverse wall shear stress. Low TAWSS is known as pro atherogenic, in contrast to all the other shear stress metrics, at which a high magnitude is pro-atherogenic. The arteries were divided into 1.5mm/45° sectors. Based on NIRS-IVUS, wall thickness change over time was determined and NIRS positive sectors detected. Furthermore, per vessel the shear stress was divided into tertiles (low, intermediate, high). To investigate the synergistic effect of local lipids on shear stress related plaque growth, wall thickness change over time was related to the different shear stress metrics comparing the NIRS-positive with the NIRS-negative sectors. Results 15 non-culprit coronary arteries from the first 14 patients were analyzed (age 62±10 years old and 92.9% male). A total of 2219 sectors were studied (5.2%, N=130, NIRS-positive) for wall thickness changes. After studying all five shear stress metrics, we found for TAWSS and RRT that presence of lipids, as detected by NIRS, amplified the effect of shear stress on plaque progression (see figure). Sectors presenting with lipid-rich plaque, compared to NIRS-negative sectors, showed more progression when they were exposed to low TAWSS (p=0.07) or high RRT (p=0.012) and more regression in sectors exposed to high TAWSS (p=0.10) or low RRT (p=0.06). Delta wall thickness vs shear stress Conclusion We presented the first preliminary results of the IMPACT study, showing the synergistic effect of lipid rich plaque and shear stress on plaque progression. Therefore, intravascular lipid-rich plaque (NIRS) assessment has added value to shear stress profiling for the prediction of plaque growth, leading to improved risk stratification. Acknowledgement/Funding ERC starting grant 310457

Shear stress and sediment transport calculations for sheet flow under waves

2003 ◽  
Vol 47 (3) ◽  
pp. 347-354 ◽  
Author(s):  
Peter Nielsen ◽  
David P. Callaghan
Keyword(s):  
Shear Stress ◽  
Sediment Transport ◽  
Sheet Flow

Topic-a cluster of relevant messages-propagation dynamics: A modeling study of the impact of user repeated forwarding behaviors

2021 ◽  
pp. 107819
Author(s):  
Fulian Yin ◽  
Zhaoliang Wu ◽  
Xueying Shao ◽  
Xinyi Tang ◽  
Tongyu Liang ◽  
...  
Keyword(s):  
Propagation Dynamics ◽  
The Impact ◽  
Modeling Study

scholarly journals A modeling study exploring the impact of homelessness on rostered primary care utilization in Calgary, Canada

2018 ◽  
Vol 109 (4) ◽  
pp. 451-458
Author(s):  
Laura A. Rivera ◽  
Matthew T. Henschke ◽  
Edwin Khoo ◽  
Stanley Ing ◽  
Sandy J. Bae ◽  
...  
Keyword(s):  
Primary Care ◽  
Care Utilization ◽  
Primary Care Utilization ◽  
The Impact ◽  
Modeling Study

scholarly journals The impact of storms and stratification on sediment transport in the Rhine region of freshwater influence

2017 ◽  
Vol 122 (5) ◽  
pp. 4456-4477 ◽  
Author(s):  
Raúl P. Flores ◽  
Sabine Rijnsburger ◽  
Alexander R. Horner-Devine ◽  
Alejandro J. Souza ◽  
Julie D. Pietrzak
Keyword(s):  
Sediment Transport ◽  
Freshwater Influence ◽  
The Impact

Analyzing the impact of wooden debris on scour and sediment transport

2020 ◽  
pp. 743-750
Author(s):  
T. Johannsen ◽  
M. Weber ◽  
N. Saenger
Keyword(s):  
Sediment Transport ◽  
The Impact
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