Numerical Simulation of Crude Oil Spreading in a Complex River Channel

2020 ◽  
Author(s):  
Dongliang Yu ◽  
Ji Wang ◽  
Quan Cao ◽  
Xinglong Zhang ◽  
Xueguang Liu
Keyword(s):  
Crude Oil ◽  
River Flow ◽  
Simulated Data ◽  
River Channel ◽  
Flowing Water ◽  
River Channels ◽  
Spreading Process ◽  
Fluid Mixture ◽  
Oil Transportation ◽  
Pass Through

Abstract Crude oil leaking in rivers may cause serious damages, such as environmental pollution and death of river animals. The crude oil spreading in rivers could be much faster than that on lands, as the leaking crude oil may flow rapidly downstream with the flowing water. Therefore, accurately estimating the transient crude oil spreading area in rivers is a vital task for emergency response and disaster rescue. However, the estimating methods in the literature mainly refer to spreading process in underwater, ocean and soil, which commonly happened in the history. The crude oil transportation pipelines in China pass through many rivers with very complex channel geometries, introducing the necessity of estimating of leaking crude oil spreading in actual river channels. In the current study, the crude oil spreading process along an actual river channel is numerically simulated. The river channel geometry is extracted from a map database, which is further treated using image binarization and edge extraction to obtain the discrete river channel data. The river channel data is then smoothed by picking less data representing main geometric characteristics. The smoothed data is used to reconstruct the river geometry and generate calculation mesh. The mesh is a two-dimensional structured grid with several possible leaking points along the actual crude oil transportation pipeline passing through the river. A multi-fluid MIXTURE model is used to simulate the crude oil spreading process on the water surface, meaning crude oil blending in the flowing water. Cases with a leaking mass flow rate of 240 kg/s and a river flow velocity of 1.58 m/s are simulated for 10 possible leaking sources on the traversing pipeline. The effect of leaking locations and river channel bending on crude oil spreading on river surface were significant according to the simulation results. Sudden widening river channel may result in vortexes and slightly delays the crude oil spreading. The simulated data could be used to make the rescue strategy of crude oil leaking in this specific river.

scholarly journals Barrier-based Longitudinal Connectivity Index for Managing Urban Rivers

Water ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1701 ◽  
Author(s):  
Heying Li ◽  
Demin Zhou ◽  
Shanshan Hu ◽  
Jianchen Zhang ◽  
Yuemei Jiang ◽  
...  
Keyword(s):  
River Flow ◽  
Flood Hazard ◽  
River Channel ◽  
Connectivity Index ◽  
Flood Hazards ◽  
River Channels ◽  
River Flooding ◽  
Longitudinal Connectivity ◽  
Restoration Measure ◽  
Comprehensive Classification

A large variety of barriers can affect longitudinal connectivity, which leads to shipping blocking and even flood hazard. However, few existing methods can quantify physically the river channel connectivity from the barrier’s details perspective in a watershed. This paper establishes a new model of the River Channel Connectivity Index (RCCI) to quantify the unobstructed degree of river flow in river channels within geographic information system (GIS ) platforms based on the modified concept of time accessibility. A comprehensive classification system of barriers is setup before these barriers are identified by the remote sensing technology. The model is applied to Dashi Watershed in suburban Beijing, China. Results show that submersible bridges and sediment siltation are the main barriers in the watershed. RCCI values in the mountainous areas are generally higher than that of the plains. The assessment results verified by two historical flood events show that the RCCI can reveal where the river channel connectivity is impaired, how serious it is, and what the reason is for managers. Through scenarios’ results, the best restoration measure for each tributary is obtained from the perspective of reducing flood hazards. The new RCCI method not only has methodological significance, but also helps policymakers to enhance river flooding reduction and determine restoration priorities of the river channel.

Simulation of Crude Oil Transportation with Drag Reduction Agents Using k-ϵ and k-ω Models

2021 ◽  
Author(s):  
Ali Nasir Khalaf ◽  
Asaad A. Abdullah
Keyword(s):  
Experimental Data ◽  
Drag Reduction ◽  
Crude Oil ◽  
Simulated Data ◽  
Fluid Equation ◽  
Oil Transportation ◽  
Different Types ◽  
Oil Flow ◽  
Simulation Results ◽  
Reduction Percentage

This work explores the possibility of using Newtonian turbulence k−ϵ and k−ω models for modelling crude oil flow in pipelines with drag reduction agents. These models have been applied to predict the friction factor, pressure drop and the drag reduction percentage. The simulation results of both models were compared with six published experimental data for crude oil flow in pipes with different types of drag reduction agents. The velocity near the wall was determined using the log law line of Newtonian fluid equation and by changing the parameter ΔB to achieve an excellent agreement with experimental data. Simulated data for k−ϵ model shows better agreement with most experimental data than the k−ω turbulence model.

Survival of fish passing downstream at a small hydropower facility

2018 ◽  
Vol 69 (12) ◽  
pp. 1870 ◽  
Author(s):  
Stephen V. Amaral ◽  
Benjamin S. Coleman ◽  
Jenna L. Rackovan ◽  
Kelly Withers ◽  
Benjamin Mater
Keyword(s):  
Mississippi River ◽  
River Flow ◽  
Survival Rates ◽  
Fish Populations ◽  
Negative Effects ◽  
Small Hydropower ◽  
The Usa ◽  
Pass Through ◽  
Hydro Project ◽  
Total Project

Hydropower dams can negatively affect upstream and downstream migratory fish populations in many ways, such as blocking access to upstream habitats and causing injuries or mortality during downstream passage. For downstream passage at projects in the USA, federal regulators and agencies responsible for oversight of hydropower facilities typically require assessment studies and mitigation to address negative effects, with a primary goal of minimising fish impingement and turbine entrainment and mortality. So as to assess the effects of downstream passage of fish populations at a unique, small hydro project on the Mississippi River, impingement and entrainment rates, Oberymeyer gate passage, spillway gate passage, turbine survival, and total downstream passage survival were estimated. It was determined that 85% of fish passing downstream at the project would be small enough to pass through the bar spacing of the trash racks and 15% would be physically excluded. When 55% of river flow enters the turbine intake channel, the total project survival rates were estimated to be 77.3% with an Obermeyer gate bypass rate of 10 and 96.6% with a gate bypass rate of 90%. Therefore, any effects on local fish populations resulting from the operation of the project are expected to be negligible and inconsequential on the basis of expected survival rates for the range and probability of river flows occurring at the project.

scholarly journals Numerical Simulation of Effects of River Reconstruction on Flooding: A Case Study of the Ba River, China

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Haixiao Jing ◽  
Yongbiao Lang ◽  
Xinhong Wang ◽  
Mingyang Yang ◽  
Zongxiao Zhang
Keyword(s):  
Flow Velocity ◽  
Eddy Currents ◽  
Human Life ◽  
River Channel ◽  
Computational Domain ◽  
River Channels ◽  
One Dimensional ◽  
Local Reconstruction ◽  
Before And After ◽  
Flood Flow

The local reconstruction of river channels may pose obstacles of flood flow, local eddy currents, or high flow velocity which pose potential threats to human life and infrastructures nearby. In the design of such projects, the effects of local reconstruction of the river channel on flooding are often evaluated by the one-dimensional method, which is based on the formula of one-dimensional nonuniform flow. In this study, a two-dimensional hydrodynamic model based on shallow water equations is employed to investigate the impacts of river reconstruction on flooding in the Ba River, China. The finite volume method and an unstructured triangular mesh are used to solve the governing equations numerically. The numerical model is validated by comparison with the results of a physical model of 1 : 120 scale. The backwater effects and impacts of flood flow fields under two flood frequencies are analyzed by comparing the numerical results before and after local reconstruction. The results show that the backwater length under both 10-year and 100-year floods can be reached up to the upstream boundary of the computational domain. However, the maximum water level rises are limited, and the levees in this river channel are safe enough. The flow velocity fields under both floods are changed obviously after local reconstruction in the Ba River. Areas with the potential for scour and deposition of the river bed are also pointed out. The findings of this study are helpful for the evaluation of flood risks of the river.

Persistence of plankton in flowing water

2007 ◽  
Vol 64 (12) ◽  
pp. 1693-1702 ◽  
Author(s):  
D J Walks
Keyword(s):  
Average Rate ◽  
Flowing Water ◽  
River Channels ◽  
Flow Heterogeneity ◽  
Planktonic Food ◽  
Drift Model ◽  
Human Modification ◽  
Slow Moving ◽  
Downstream Flow ◽  
Passive Drift

Models of river plankton frequently suggest that these passively drifting communities are limited to downstream sections of larger rivers. I examine this hypothesis using a passive drift model for populations in advective environments, followed by a comparison of predicted and observed plankton populations in rivers. Under the scenario of continuous downstream drift, much of the plankton found in rivers is not predicted to occur. However, much of the observed plankton in rivers is explained through the addition of cross-channel flow heterogeneity to the model. Empirical data support the model and predict that many river plankton populations may be drifting downstream at less than 30% of the average rate of downstream flow. Plankton collections in the slower-moving edges of rivers demonstrate densities of up to 240% higher than those in adjacent midchannel flows (p = 0.009). These slow-moving areas are important habitat for river plankton and likely play a large role in planktonic food webs within rivers. These results may help explain why river productivity often decreases as a result of the loss of flow heterogeneity within river channels through human modification to landscapes.

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