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

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

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.

scholarly journals Particle Responses to Near-Bed Shear Stress in a Shallow, Wave- and Current-Driven Environment

2021 ◽  
Author(s):  
Grace Chang ◽  
Galen Egan ◽  
Joseph D McNeil ◽  
Samuel McWilliams ◽  
Craig Jones ◽  
...  
Keyword(s):  
Shear Stress ◽  
Bed Shear Stress

scholarly journals Study on bed shear stress around channel constriction.

1985 ◽  
pp. 115-121
Author(s):  
Susumu HASHIMOTO ◽  
Yoshitaka FUKUI ◽  
Hideo KIKKAWA
Keyword(s):  
Shear Stress ◽  
Bed Shear Stress ◽  
Channel Constriction

The influence of deposit body on the near-bed shear stress

2021 ◽  
pp. 1-29
Author(s):  
Yan He ◽  
Jing Zhang ◽  
Huling Jiang ◽  
Zhixue Guo ◽  
Hongxi Zhao
Keyword(s):  
Shear Stress ◽  
Bed Shear Stress

scholarly journals Numerical Study on Shear Stress Variation of RC Wall with L Shaped Section

2015 ◽  
Vol 59 (1) ◽  
pp. 15-25 ◽  
Author(s):  
Ali Ahmed Chaouch ◽  
Ramdane Boutemeur ◽  
Hakim Bechtoula ◽  
Abderrahim Bali
Keyword(s):  
Shear Stress ◽  
Numerical Study ◽  
Stress Variation ◽  
Shaped Section

Use of Large-Eddy Simulation for the bed shear stress estimation over a dune

2019 ◽  
Author(s):  
Adrien Bourgoin ◽  
Sylvain S. Guillou ◽  
Jérôme Thiébot ◽  
Riadh Ata
Keyword(s):  
Shear Stress ◽  
Large Eddy Simulation ◽  
Bed Shear Stress ◽  
Eddy Simulation ◽  
Large Eddy ◽  
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

scholarly journals Turbulence Characteristic of Flow Near Laboratory Experiment Groin Fields

2019 ◽  
Vol 24 (2) ◽  
pp. 167
Author(s):  
Pradipta Nandi Wardhana
Keyword(s):  
Shear Stress ◽  
Laboratory Experiment ◽  
Reynolds Stress ◽  
Flow Region ◽  
Turbulence Characteristic ◽  
Bed Shear Stress ◽  
Primary Flow ◽  
Flow Area ◽  
Number Range ◽  
Downstream Area

Groin is hydraulic structure utilized to protect riverbank from erosion. Groin will shift away flow. Area just downstream of groin structure will be occupied by low velocity flow hence there will be sediment deposition. Turbulence mechanism between primary flow region and groin field having important role in sediment exchange needs to be investigated. Instantaneous flow measurement was conducted in order to investigate turbulence relation between series groin under various groin spacing. Laboratory experiment employed turbulence flow having Reynolds number range between 31,935-32,500 and Froude number range between 0.051-0.053. A MicroADV 16-MHz was used to measure 3D instantaneous velocity. The experiment findings expressed that Reynolds stress involving vertical velocity  and    did not show any specific distributions except at the lowest measurement elevation, while Reynolds stress    showed specific distributions. Turbulence value difference between groin field and primary flow region at upstream of the groin field was significant. As the area was getting downstream, area containing high turbulence was wider. This work indicated that bed shear stress value  tended to grow at downstream area of groin field. High difference bed shear stress value  between primary flow region and groin field seized second groin field and third groin field.

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