Numerical Investigation of Impact of Pile Space on Flow around Two Vertical Cylindrical Piles

2012 ◽  
Vol 212-213 ◽  
pp. 1103-1107
Author(s):  
Jian Wen Qi ◽  
Cui Ping Kuang ◽  
Jie Gu ◽  
Jing Huang
Keyword(s):  
Shear Stress ◽  
Current Velocity ◽  
Three Dimensional ◽  
Horseshoe Vortex ◽  
Wake Vortex ◽  
Physical Factors ◽  
Bottom Shear Stress ◽  
Steady Current ◽  
Maximum Current ◽  
Cylindrical Piles

The flow around two vertical cylindrical piles exposed to a steady current is studied numerically by a three-dimensional hydrodynamic model, which is closured with a k-ε turbulence model. This model is firstly validated by experimental data obtained from a labortory experiment for a steady flow through a circular pile. Then this validated model is used to study flow pattern around two cylindrical piles. Finally, four key physical factors of the size of the horseshoe vortex and lee wake vortex, the maximum current velocity and bottom shear stress are analyzed under the different pile spaces. The main conclusions are: i) the size of the horseshoe vortex increases with the increase of the two pile space, while the size of the lee wake vortex changes slightly; ii) the maximum current velocity and the maximum bottom shear stress decrease with the increase of two pile space, and reach steady after the two pile space larger than six times of cylindrical pile diameter.

scholarly journals CHANGES IN CURRENT PROPERTIES DUE TO WAVE SUPERIMPOSING

1986 ◽  
Vol 1 (20) ◽  
pp. 70 ◽  
Author(s):  
Toshiyuki Asano ◽  
Masahiro Nakagawa ◽  
Yuichi Iwagaki
Keyword(s):  
Shear Stress ◽  
Velocity Profile ◽  
Energy Conservation ◽  
Current Velocity ◽  
Conservation Equation ◽  
Bottom Shear Stress ◽  
Energy Conservation Equation ◽  
Friction Term ◽  
Mean Water Level ◽  
The Mean

Changes in current properties due to wave superimposing are investigated experimentally. Variations of the mean water level gradient and the current velocity profile after wave superimposing are examined. Experimental results are discussed in relation to the energy conservation equation including the bottom friction term. It is found that changes in current properties can be well explained by increase in the time averaged bottom shear stress.

Measurement and numerical modeling studies of the highest bottom shear stress in the Randle Reef area

2014 ◽  
Vol 41 (9) ◽  
pp. 828-838 ◽  
Author(s):  
Cheng He ◽  
Eric Scott ◽  
Matthew Graham ◽  
Andrew Binns
Keyword(s):  
Shear Stress ◽  
Three Dimensional ◽  
Open Water ◽  
Bottom Layer ◽  
Velocity Profiles ◽  
Flow Speed ◽  
Model Verification ◽  
Bottom Shear Stress ◽  
Study Region ◽  
Quadratic Formula

The purpose of this study was to investigate the highest bottom shear stress, induced by wind in an area of Hamilton Harbour, Ontario, Canada known as Randle Reef. The study was conducted in support of a component of a contaminated sediment remediation plan utilizing a thin layer of sand to manage contaminated sediments. Toward this end, four acoustic Doppler current profilers (ADCPs) were deployed at two locations in the study region to measure velocity profiles for the purpose of indirectly measuring bottom shear stress (BSS) and model verification. There is no easy way to directly measure BSS in the field. As a result, the use of the logarithmic-profile method from the ADCP measured high resolution velocity profiles in the bottom layer was explored. This approach, according to our best knowledge, has not been published for a wind driven flow in a small open water body. To use the indirectly measured BSS to estimate the highest BSS in the study area, a three-dimensional hydrodynamic model was adopted to provide the spatial and temporal information of the bottom flow. The results showed that the modeled and measured flow velocity components agreed reasonably well at most of the water depths with the correlation coefficients being greater than 0.6. However, agreements between the modeled and measured bottom flow speeds were worse than expected due to the error contributions from both the modeled velocity components. Therefore, the modeled flow speed required rescaling based on ADCP velocity measurements before it could be deemed reliable. This is especially important in estimation of the BSS with a quadratic formula because the calculated BSS is proportional to the square of the speed.

scholarly journals Three-Dimensional Numerical Modelling of Tidal Current in Balikpapan Bay Using Delft 3D

2021 ◽  
Vol 925 (1) ◽  
pp. 012051
Author(s):  
Syarifah Fauzah ◽  
Ayi Tarya ◽  
Nining Sari Ningsih
Keyword(s):  
Shear Stress ◽  
Current Velocity ◽  
Spring Tide ◽  
Three Dimensional ◽  
Observation Point ◽  
Ocean Current ◽  
Percentage Error ◽  
Maximum Speed ◽  
Bed Shear Stress ◽  
Residential Areas

Abstract Balikpapan is one of the main port cities with residential areas, industry, trade, and vital objects scattered from north to south along the coast of Balikpapan Bay. This dense activity increases traffic in Balikpapan Bay. Thus, the hydrodynamic conditions in these waters are essential to be reviewed. The purpose of this research is to simulate hydrodynamics in Balikpapan Bay. The simulation results of the hydrodynamic model for sea-level elevation values are close to the conditions in the field, as indicated by the correlation coefficient 0.98, skill 0.99, and RMSE 0.15 m. The ocean current velocity verification includes the average correlation for x-direction and y-direction, up to 0.93, RMSE 0.05 m, and the percentage error of 6.7%. The significant current velocity is at low tide during spring tide with an average of 0.1 m/s and a maximum speed of 1.62 m/s. Temporally, the observation point at the mouth of Balikpapan Bay has the most significant Bed Shear Stress magnitude with an average of 0.05 N/m2. Spatially, the highest Bed Shear Stress magnitude is at the time of spring tide when it recedes towards the tide with an average Bed Shear Stress in the bay of 0.16 N/m2. The most dominant tidal components are M2 and S2, with a contribution value of 65.3%. The phase propagation from mouth to upstream of Balikpapan Bay for the M2 component in Balikpapan Bay is 10.5° (22.77 minutes) and 5.5° (11 minutes) for the S2 component.

Impact of the Level of Approximation on Modeling Flushing Waves

2007 ◽  
Vol 2 (2) ◽  
Author(s):  
P. Staufer ◽  
J. Dettmar ◽  
J. Pinnekamp
Keyword(s):  
Shear Stress ◽  
Numerical Models ◽  
Three Dimensional ◽  
Shear Stresses ◽  
Bottom Shear Stress ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Successful Operation ◽  
One Dimensional ◽  
The One

Sewer cleaning with the means of flushing offers the possibility to place sewers free of deposit if flushing waves are generated continuously or quasi-continuously by suitable flushing devices. Numerical investigations should be carried out regarding different hydraulic circumstances because sewer networks consist of various compounds with complex geometries e.g. cross-section alignment or special structures. To accomplish a stable and successful operation of flushing devices it seems necessary to use different level of approximation on modelling flushing waves. Thereby both accuracy and running-time of simulations with numerical models will be optimized. This paper presents differences and similarities of the simulation results of a one-dimensional and a three-dimensional model of flushing wave within a big sized sewer. As assumed the one-dimensional model becomes less accurate when the complexity of the geometry increases. The three-dimensional model shows an underestimation of velocity and bottom shear-stress at the flushing head due to energy losses within the water body. Contrary, the one-dimensional model overestimates bottom shear-stress at the flushing head because of a stationary basic approach which is used. However, real highly resolved measurements of bottom shear-stresses are required to confirm the results in detail.

scholarly journals Three-Dimensional Numerical Investigations of the Flow Pattern and Evolution of the Horseshoe Vortex at a Circular Pier during the Development of a Scour Hole

2021 ◽  
Vol 11 (15) ◽  
pp. 6898
Author(s):  
Ahmed M. Helmi ◽  
Ahmed H. Shehata
Keyword(s):  
Shear Stress ◽  
Flow Structure ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Horseshoe Vortex ◽  
Bed Shear Stress ◽  
Scour Hole ◽  
Scouring Depth ◽  
Mean Size ◽  
Stress Variations

In the current study, a three-dimensional CFD model is utilized to investigate the variation of the flow structure and bed shear stress at a single cylindrical pier during scour development. The scour development is presented by seven solidified geometries of the scour hole, collected during previous experimental work at different scour stages. Different turbulence models are evaluated and the (k-ω) model is chosen due to its relative accuracy in capturing the flow oscillation and vortex shedding at the pier downstream side with personal computer computational and storage resources. The numerical results are verified against dimensionless parameters from different previous experimental works. This research describes in detail the flow structure and bed shear stress variations through seven stages of the scour hole development. The dimensionless area-averaged circulation coefficient (Ψi) is developed to evaluate the changes in the vortex strength through the scouring process by eliminating the calculation area effect. It was concluded that the circulation in the (Y) direction is the main driving factor in the development of the scour hole more than the circulation in the (X) direction. The ratio between the horseshoe vortex (HV) mean size and the scouring depth (DV/dS) in addition to the location of the maximum bed shear stress are investigated during different stages of the scour development.

scholarly journals RELATIONSHIP BETWEEN BOTTOM SHEAR STRESS AND TURBIDITY IN ESTUARIES

2011 ◽  
Vol 67 (4) ◽  
pp. I_1591-I_1596
Author(s):  
Jun-ichi SAKAMOTO ◽  
Haruhiko MATSUMOTO ◽  
Kesayoshi HADANO ◽  
Takuzo AMANO ◽  
Kiyonobu MITSUNOBU
Keyword(s):  
Shear Stress ◽  
Bottom Shear Stress

scholarly journals Bicuspid Aortic Cusp Fusion Morphology Alters Aortic Three-Dimensional Outflow Patterns, Wall Shear Stress, and Expression of Aortopathy

Circulation ◽  
2014 ◽  
Vol 129 (6) ◽  
pp. 673-682 ◽  
Author(s):  
Riti Mahadevia ◽  
Alex J. Barker ◽  
Susanne Schnell ◽  
Pegah Entezari ◽  
Preeti Kansal ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Three Dimensional ◽  
Aortic Cusp ◽  
Wall Shear
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