A RANS numerical study of experimental swash flows and its bed shear stress estimation

2020 ◽  
Vol 100 ◽  
pp. 102145
Author(s):  
By Peng Hu ◽  
Jiafeng Xie ◽  
Wei Li ◽  
Zhiguo He ◽  
Reza Marsooli ◽  
...  
Keyword(s):  
Shear Stress ◽  
Numerical Study ◽  
Bed Shear Stress ◽  
Stress Estimation

Bed Shear Stress Estimation Under Wave Conditions Using near-bottom Measurements: Comparison of Methods

2018 ◽  
Vol 85 ◽  
pp. 241-245
Author(s):  
Qian Zhang ◽  
Zheng Gong ◽  
Changkuan Zhang ◽  
Jessica R. Lacy ◽  
Bruce E. Jaffe ◽  
...  
Keyword(s):  
Shear Stress ◽  
Bed Shear Stress ◽  
Comparison Of Methods ◽  
Stress Estimation ◽  
Wave Conditions

Numerical study of ship induced bed shear stress

2020 ◽  
pp. 2338-2342
Author(s):  
Malasani Gopichand ◽  
Tapas Kumar Pradhan ◽  
K Murali ◽  
Venu Chandra
Keyword(s):  
Shear Stress ◽  
Numerical Study ◽  
Bed Shear Stress

scholarly journals Comparison of Methods for Bed Shear Stress Estimation in Complex Flow Field of Bend

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2753
Author(s):  
Liyuan Zhang ◽  
Faxing Zhang ◽  
Ailing Cai ◽  
Zhaoming Song ◽  
Shilin Tong
Keyword(s):  
Shear Stress ◽  
Flow Field ◽  
Single Point ◽  
Three Dimensional ◽  
Bed Shear Stress ◽  
Complex Flow ◽  
Three Dimensional Flow ◽  
Stress Estimation ◽  
Log Law ◽  
Flow Field Measurement

Bed shear stress is closely related to sediment transport in rivers. Bed shear stress estimation is very difficult, especially for complex flow fields. In this study, complex flow field measurement experiments in a 60° bend with a groyne were performed. The feasibility and reliability of bed shear stress estimations using the log-law method in a complex flow field were analyzed and compared with those associated with the Reynolds, Turbulent Kinetic Energy (TKE), and TKE-w′ methods. The results show that the TKE, Reynolds, and log-law methods produced similar bed shear stress estimates, while the TKE-w′ method produced larger estimates than the other methods. The TKE-w′ method was found to be more suitable for bed shear stress estimation than the TKE method, but the value of its constant C2 needed to be re-estimated. In a complex, strong, three-dimensional flow field, the height of the measurement point (relative or absolute) should be re-estimated when a single point measurement is used to estimate the bed shear stress. The results of this study provide guidance for experimental measurement of bed shear stress in a complex flow field.

Bed shear stress estimation on an open intertidal flat using in situ measurements

2016 ◽  
Vol 182 ◽  
pp. 190-201 ◽  
Author(s):  
Q. Zhu ◽  
B.C. van Prooijen ◽  
Z.B. Wang ◽  
Y.X. Ma ◽  
S.L. Yang
Keyword(s):  
Shear Stress ◽  
In Situ Measurements ◽  
Intertidal Flat ◽  
Bed Shear Stress ◽  
Stress Estimation

Gravity Anchors Astride Subsea Pipelines Subject to Oscillatory and Combined Steady and Oscillatory Flows

2012 ◽  
Author(s):  
Xu Zhao ◽  
Liang Cheng ◽  
Ming Zhao ◽  
Hongwei An ◽  
Wei He
Keyword(s):  
Shear Stress ◽  
Oscillatory Flow ◽  
Stokes Equations ◽  
Numerical Study ◽  
Shear Stresses ◽  
Bed Shear Stress ◽  
Oscillatory Flows ◽  
Steady Current ◽  
Stress Amplification ◽  
Subsea Pipelines

This writing presents results of simulating oscillatory and combined steady and oscillatory flows past gravity anchors astride subsea pipelines. It can be considered a companion to a previous numerical study on steady currents past gravity anchors. The gravity anchor system comprises large arch-shaped concrete blocks positioned at intervals astride offshore pipelines, and it is engineered to provide innovative and cost-effective secondary stabilisation for high-capacity gas-transporting pipelines serving in severe metocean conditions, e.g. cyclone-prone offshore areas. A free-settling marine object bottom-seated on the seabed, however, the gravity anchor may subside into scour pits around its base due to locally disturbed flow regimes, imposing integrity risks on the pipe. Also, the effect of gravity anchors on hydrodynamic loading on nearby pipeline lengths is of interest. The present study employed a Petrov-Galerkin finite element method to solve the three-dimensional Navier-Stokes equations in direct numerical simulation. Firstly sinusoidal flow oscillating perpendicularly to the pipe beneath gravity anchors on an immobile bed was simulated at a Keulegan-Carpenter number of 10 and a pipe Reynolds number of 1000. Then, a steady current co-directionally superimposed on the aforementioned oscillatory flow was modelled at a ratio of steady current velocity to oscillatory flow velocity amplitude of 1. With sediment transport capacity related to bed shear stresses, the time-averaged bed shear stress amplification around gravity anchors in oscillatory flow was revealed first, and found to be consistent with laboratory observations of scour patterns. The effect of superimposing steady flow onto oscillatory flow on bed shear stress amplification was then explored. Lastly, hydrodynamic forces on pipelines in the vicinity of gravity anchors were gauged. The present work intends to shed light on the initial seabed responses with regard to the scour process around gravity anchors immersed in the oceanic wave boundary layer, as well as the effect of gravity anchors on hydrodynamic loadings on pipelines.

Efficiency prediction for storage chambers using computational fluid dynamics

1996 ◽  
Vol 33 (9) ◽  
pp. 163-170 ◽  
Author(s):  
Virginia R. Stovin ◽  
Adrian J. Saul
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Shear Stress ◽  
Particle Tracking ◽  
Critical Value ◽  
Complex Geometries ◽  
Bed Shear Stress ◽  
Breadth Ratio ◽  
Computational Fluid Dynamics Cfd ◽  
Simulated Flow

Research was undertaken in order to identify possible methodologies for the prediction of sedimentation in storage chambers based on computational fluid dynamics (CFD). The Fluent CFD software was used to establish a numerical model of the flow field, on which further analysis was undertaken. Sedimentation was estimated from the simulated flow fields by two different methods. The first approach used the simulation to predict the bed shear stress distribution, with deposition being assumed for areas where the bed shear stress fell below a critical value (τcd). The value of τcd had previously been determined in the laboratory. Efficiency was then calculated as a function of the proportion of the chamber bed for which deposition had been predicted. The second method used the particle tracking facility in Fluent and efficiency was calculated from the proportion of particles that remained within the chamber. The results from the two techniques for efficiency are compared to data collected in a laboratory chamber. Three further simulations were then undertaken in order to investigate the influence of length to breadth ratio on chamber performance. The methodology presented here could be applied to complex geometries and full scale installations.

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