scholarly journals Flow characteristics of individual lot stormwater detention

2016 ◽  
Vol 11 (4) ◽  
pp. 721-727
Author(s):  
Johnny Ong King Ngu ◽  
Darrien Yau Seng Mah ◽  
Charles Hin Joo Bong
Keyword(s):  
Turbulent Flow ◽  
Fluid Dynamic ◽  
Flow Characteristics ◽  
Scale Model ◽  
Storage Tanks ◽  
Cfd Simulations ◽  
Detention Tank ◽  
Cfd Models ◽  
Underground Storage Tanks ◽  
Run Off

In this paper the flow characteristics of stormwater are analyzed as it travels from a roof gutter down-pipe and the turbulent flow generated on entering an individual lot on-site stormwater detention (OSD) unit beneath a residential carport. Comparison was made between a full-scale model and computational fluid dynamic (CFD) simulations to determine the flow characteristics. These modular tanks with multi-unit chambers can capture the roof run-off from a 15-minute, 10-year return period storm. The results from the physical and CFD models matched well, suggesting that turbulent flow occurs when stormwater is directed to an individual lot stormwater detention tank. However, turbulence in the OSD was concentrated around the inlet, after which the pattern changed from turbulent to laminar flow. This work implies that the use of modular underground storage tanks is practical for managing stormwater from a roof.

scholarly journals Frictional Pressure Drop and Cost Savings for Graphene Nanoplatelets Nanofluids in Turbulent Flow Environments

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 3094
Author(s):  
Reem Sabah Mohammad ◽  
Mohammed Suleman Aldlemy ◽  
Mu’ataz S. Al Hassan ◽  
Aziz Ibrahim Abdulla ◽  
Miklas Scholz ◽  
...  
Keyword(s):  
Turbulent Flow ◽  
Fluid Dynamic ◽  
Cost Savings ◽  
Graphene Nanoplatelets ◽  
Average Error ◽  
Cfd Simulations ◽  
Frictional Pressure Drop ◽  
Fully Developed Turbulent Flow ◽  
Research Findings ◽  
The Cost

Covalent-functionalized graphene nanoplatelets (CF-GNPs) inside a circular heated-pipe and the subsequent pressure decrease loss within a fully developed turbulent flow were discussed in this research. Four samples of nanofluids were prepared and investigated in the ranges of 0.025 wt.%, 0.05 wt.%, 0.075 wt.%, and 0.1 wt.%. Different tools such as field emission scanning electron microscopy (FE-SEM), ultraviolet-visible-spectrophotometer (UV-visible), energy-dispersive X-ray spectroscopy (EDX), zeta potential, and nanoparticle sizing were used for the data preparation. The thermophysical properties of the working fluids were experimentally determined using the testing conditions established via computational fluid dynamic (CFD) simulations that had been designed to solve governing equations involving distilled water (DW) and nanofluidic flows. The average error between the numerical solution and the Blasius formula was ~4.85%. Relative to the DW, the pressure dropped by 27.80% for 0.025 wt.%, 35.69% for 0.05 wt.%, 41.61% for 0.075 wt.%, and 47.04% for 0.1 wt.%. Meanwhile, the pumping power increased by 3.8% for 0.025 wt.%, 5.3% for 0.05 wt.%, 6.6% for 0.075%, and 7.8% for 0.1 wt.%. The research findings on the cost analysis demonstrated that the daily electric costs were USD 214, 350, 416, 482, and 558 for DW of 0.025 wt.%, 0.05 wt.%, 0.075 wt.%, and 0.1 wt.%, respectively.

Numerical and Experimental Analyses of Breakwater Designs for Turbulent Flow Characteristics and Sediment Transport Under Coastal Wave Actions

2020 ◽  
Vol 142 (7) ◽  
Author(s):  
Hairui Wang ◽  
William Foltz ◽  
Ning Zhang ◽  
Dimitrios Dermisis
Keyword(s):  
Coastal Erosion ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Sediment Retention ◽  
Cfd Simulations ◽  
Cfd Models ◽  
Turbulent Characteristics ◽  
Scale Down ◽  
Pass Through ◽  
Coastal Louisiana

Abstract The goal of the study is to identify optimal breakwater designs to be placed on the banks of various water bodies in coastal Louisiana, to prevent the coastal erosion. Coastal erosion is a significant concern for Louisiana's wavy coastline. The loss of coastal wetlands is threatening the environment and the economic development. One of the ways to prevent coastal erosion and wetland losses is by using breakwaters designed to reduce the wave energy and change the transport of sediments brought by the waves. The objective of this research is to analyze the turbulent characteristics around specially designed three-dimensional (3D) breakwaters, and its impact on sediment deposition under coastal wave actions. Both computational fluid dynamics (CFD) simulations and experimental measurements were conducted. In order to validate the CFD models used for this study, the simulation results were compared to data measured from a scale-down experiment. Once the validity of the CFD models has been confirmed on three miniature panels, namely, a solid panel, a panel with three holes, and a panel with eight holes, the simulations were scaled up to the actual size of the designed breakwater panels for tests. The breakwater designs aim to allow sediment pass through the holes, to deposit sediment at target areas, and to reduce wave actions. There were three different panel-design cases simulated in this study. The results of 3D CFD simulations of these panels were compared and analyzed to determine the performance of each design in terms of wave reduction and sediment retention.

CFD Analysis of Turbulent Flow in a Nuclear Fuel Bundle With Mixing Vane

2002 ◽  
Author(s):  
Wang Kee In ◽  
Dong Seok Oh ◽  
Tae Hyun Chun
Keyword(s):  
Turbulent Flow ◽  
Nuclear Fuel ◽  
Cfd Simulation ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Cfd Analysis ◽  
Mean Flow ◽  
Cfd Models ◽  
Fuel Bundle ◽  
Rod Array

A computational fluid dynamics (CFD) analysis was performed to investigate the coolant mixing in a nuclear fuel bundle that is promoted by the mixing vane on the grid spacer. Single and multiple subchannels of one grid span of the fuel bundle were modeled to simulate a 5×5 rod array experiment with the mixing vane. The three-dimensional CFD models were generated by a structured multi-block method. The standard k-ε turbulence model was used in the current CFD simulation since it is practically useful and converges well for the complex turbulent flow in a nuclear fuel bundle. The CFD predictions of axial and lateral mean flow velocities showed a somewhat large difference from the experimental results near the spacer but represented the overall characteristics of coolant mixing well in a nuclear fuel bundle with the mixing vane. Comparison of single and multiple subchannel predictions shows good agreement of the flow characteristics in the central subchannel of the rod array. The simulation of multiple subchannels shows a slightly off-centered swirl in the peripheral subchannels due to the external wall of the rod array. It also shows no significant swirl and crossflow in the wall subchannels and the corner subchannels.

Slender Buoy FSHR Vortex Induced Rotations

2012 ◽  
Author(s):  
Matthieu Minguez ◽  
Ange Luppi ◽  
Anthony Berger
Keyword(s):  
Turbulent Flow ◽  
Flow Regime ◽  
Computational Fluid Dynamic ◽  
Fluid Dynamic ◽  
Cross Flow ◽  
Induced Response ◽  
Cfd Simulations ◽  
Turbulent Flow Regime ◽  
Surface Buoyancy ◽  
Lock In

The paper addresses the Flow Induced Response (FIR) of a sub-surface Buoyancy Can (BC) and more particularly the yaw motions possibly due to the current vortices. 2D Computational Fluid Dynamic (CFD) simulations have been performed to analyse the turbulent flow regime over a BC. Thereafter 1 DOF and 2 DOF BC responses i.e. yaw and cross flow responses are analysed. Focusing on the yaw behaviour, a lock-in has been observed from which yaw rotations develop. The Yaw and Cross Flow (CF) appear to be coupled. As already mentioned in [8], the presence of yaw tends to weaken the CF vortex induced motions (VIM). When the 2 DOF natural periods are somehow closer, the CF response tends to be recovered.

The Wall Shear Stress Vector: Methods for Characterising Truly Disturbed Flow

2012 ◽  
Author(s):  
Véronique Peiffer ◽  
Peter D. Weinberg ◽  
Spencer J. Sherwin
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Fluid Dynamic ◽  
Flow Characteristics ◽  
New Method ◽  
Molecular Signaling ◽  
Stress Vector ◽  
Cfd Simulations ◽  
Disturbed Flow ◽  
Wall Shear

Haemodynamic stresses acting on the arterial wall may play an important role in the initiation and development of atherosclerosis, and in particular are likely to explain its focal occurrence. Computational fluid dynamic (CFD) simulations of blood flow in arteries have been widely used to investigate this relation and a variety of metrics have been derived to link flow characteristics with lesion prevalence [1]. Although the initial focus was on the magnitude of the time-averaged wall shear stress (TAWSS), an oscillatory shear index (OSI) was subsequently introduced “to describe the shear stress acting in directions other than the direction of the temporal mean shear stress vector” [2]. Biological evidence suggests that flow without a definite direction, in contrast to shear with a clear direction (whether resulting from steady or pulsatile flow), causes sustained molecular signaling of pro-inflammatory and proliferative pathways [3]. Although the OSI has frequently been used to quantify the extent of disturbed flow, we emphasise that no singular metric can fully characterise the flow environment; in particular, we and other research groups [4] note that OSI and other similar metrics are unable to distinguish between simple uniaxial flows (which can be purely forward flowing or reversing) and multi-directional flows, which we term “truly disturbed”. We propose a new method that has this potential, and which complements existing metrics. The new method may help investigations of the importance of flow directionality.

scholarly journals Computational Analysis of Lung and Isolated Airway Bifurcations under Mechanical Ventilation and Normal Breathing

Fluids ◽  
2021 ◽  
Vol 6 (11) ◽  
pp. 388
Author(s):  
Jongwon Kim ◽  
Ramana M. Pidaparti
Keyword(s):  
Mechanical Ventilation ◽  
Fluid Dynamic ◽  
Flow Characteristics ◽  
Computational Time ◽  
Cfd Simulations ◽  
Airflow Velocity ◽  
Pressure Drops ◽  
Numerical Errors ◽  
Normal Breathing ◽  
Feasible Alternative

Mechanical ventilation is required for many patients who cannot breathe normally as a result of lung disease and other factors that result in reduced lung function. In this study, we investigated the effects of mechanical ventilation and normal breathing on whole lung geometry as well as isolated bifurcations through computational fluid dynamic (CFD) simulations. Results of flow characteristics (airflow velocity, wall pressure, and wall shear stress) obtained from the CFD simulations are presented. Similar flow patterns and pressure drops were obtained between the whole lung geometry and isolated bifurcations under both normal breathing and mechanical ventilation, respectively. Results obtained from simulations suggest that analyzing specific local bifurcations may be a more feasible alternative as it may reduce the computational time and numerical errors resulting from computations as compared to simulating a complex whole lung geometry. The approach presented in this study also demonstrated that analyses of isolated bifurcations gave similar flow characteristics to that of whole lung geometry. Therefore, this approach may be useful for quickly obtaining results that will assist in making clinical predictions and other applications.

scholarly journals Interactions between Tandem Cylinders in an Open Channel: Impact on Mean and Turbulent Flow Characteristics

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1718
Author(s):  
Hasan Zobeyer ◽  
Abul B. M. Baki ◽  
Saika Nowshin Nowrin
Keyword(s):  
Turbulent Flow ◽  
Open Channel ◽  
Recirculation Zone ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Flow Recirculation ◽  
Tandem Cylinders ◽  
Flow Development ◽  
The Mean ◽  
Recirculation Length

The flow hydrodynamics around a single cylinder differ significantly from the flow fields around two cylinders in a tandem or side-by-side arrangement. In this study, the experimental results on the mean and turbulence characteristics of flow generated by a pair of cylinders placed in tandem in an open-channel flume are presented. An acoustic Doppler velocimeter (ADV) was used to measure the instantaneous three-dimensional velocity components. This study investigated the effect of cylinder spacing at 3D, 6D, and 9D (center to center) distances on the mean and turbulent flow profiles and the distribution of near-bed shear stress behind the tandem cylinders in the plane of symmetry, where D is the cylinder diameter. The results revealed that the downstream cylinder influenced the flow development between cylinders (i.e., midstream) with 3D, 6D, and 9D spacing. However, the downstream cylinder controlled the flow recirculation length midstream for the 3D distance and showed zero interruption in the 6D and 9D distances. The peak of the turbulent metrics generally occurred near the end of the recirculation zone in all scenarios.

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