scholarly journals A Computational Fluid Dynamics Simulation Model of Sediment Deposition in a Storage Reservoir Subject to Water Withdrawal

Water ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 959
Author(s):  
Mohammad E. Mohammad ◽  
Nadhir Al-Ansari ◽  
Sven Knutsson ◽  
Jan Laue
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Sediment Load ◽  
Three Dimensional ◽  
Model Performance ◽  
Sediment Deposition ◽  
T Test ◽  
Dynamics Simulation ◽  
Water Withdrawal ◽  
Pumping Station

Siltation is one of the most common problems in storage projects and attached structures around the world, due to its effects on a project’s life span and operational efficiency. A three-dimensional computational fluid dynamics (CFD) model was applied to study the flow and sediment deposition in a multipurpose reservoir (Mosul Dam Reservoir, Iraq) subject to water withdrawal via a pumping station. A suitable control code was developed for the sediment simulation in intakes with multiblock option (SSIIM) model, in order to simulate a study case and achieve the study aims. The measured total deposited load in the reservoir after 25 years of operation and the measured sediment load concentration at different points near the pumping station intake were considered to validate the model results. The sediment load concentrations at several points near the water intake were compared; the percent bias (PBIAS) value was 3.6%, while the t-test value was 0.43, less than the tabulated value, indicating fair model performance. The model sensitivity to grid size and time steps was also tested. Four selected bed level sections along the reservoir were compared with the simulated values and indicate good performance of the model in predicting the sediment load deposition. The PBIAS ranged between 4.8% and 80.7%, and the paired t-test values indicate good model performance for most of the sections.

Experimental and simulation study of thermal accumulation in an enclosed vehicle

2019 ◽  
Vol 233 (14) ◽  
pp. 3621-3629
Author(s):  
Sing Ngie David Chua ◽  
Boon Kean Chan ◽  
Soh Fong Lim
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Dynamics Simulation ◽  
Computational Fluid Dynamics Simulation ◽  
Heat Accumulation ◽  
Ansys Fluent ◽  
Direct Exposure ◽  
Car Park

Thermal accumulation in a car cabin under direct exposure to sunlight can be extremely critical due to the risk of heatstroke especially to children who are left unattended in the car. There are very limited studies in the literature to understand the thermal behaviour of a car that is parked in an open car park space and the findings are mostly inconsistent among researchers. In this paper, the studies of thermal accumulation in an enclosed vehicle by experimental and computational fluid dynamics simulation approaches were carried out. An effective and economical method to reduce the heat accumulation was proposed. Different test conditions such as fully enclosed, fully enclosed with sunshade on front windshield and different combinations of window gap sizes were experimented and presented. Eight points of measurement were recorded at different locations in the car cabin and the results were used as the boundary conditions for the three-dimensional computational fluid dynamics simulation. The computational fluid dynamics software used was ANSYS FLUENT 16.0. The results showed that the application of sunshade helped to reduce thermal accumulation at car cabin by 11.5%. The optimum combination of windows gap size was found to be with 4-cm gap on all four windows which contributed to a 21.1% reduction in car cabin temperature. The results obtained from the simulations were comparable and in agreement with the experimental tests.

Transient Simulation of a Three-Dimensional Moving Downburst

2012 ◽  
Vol 446-449 ◽  
pp. 3875-3878
Author(s):  
Bai Feng Ji ◽  
Wei Lian Qu
Keyword(s):  
Fluid Dynamics ◽  
Numerical Simulation ◽  
Computational Fluid Dynamics ◽  
Wind Field ◽  
Three Dimensional ◽  
Simulation Method ◽  
Transient Simulation ◽  
Dynamics Simulation ◽  
Transmission Tower ◽  
Transient Wind

Thunderstorm microbursts, which are sources of extreme wind loadings in nature, have caused numerous structural failures, especially collapses of transmission tower around the world. Numerical simulation using computational fluid dynamics (CFD) has recently made significant progress in simulating downbursts. In this paper, transient simulation of a three-dimensional moving downburst was studied using computational fluid dynamics simulation method. Transient simulation of a three-dimensional moving downburst was conducted using time-filtered Reynolds Averaged Navier-Stokes (RANS) numerical simulation method. The three-dimensional transient wind field characteristics in a moving downburst were studied in detail. The results indicate that transient wind field characteristics in a moving downburst present quite different characteristics compared with stationary downburst at different heights and radial positions.

Microscale Computational Fluid Dynamics Simulation for Wind Mapping Over Complex Topographic Terrains

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Ashkan Rasouli ◽  
Horia Hangan
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Spatial Resolution ◽  
Three Dimensional ◽  
Dynamics Simulation ◽  
Scale Model ◽  
Cfd Model ◽  
Cfd Simulations ◽  
Wide Range ◽  
Wind Mapping

Wind mapping is of utmost importance in various wind energy and wind engineering applications. The available wind atlases usually provide wind data with low spatial resolution relative to the wind turbine height and usually neglect the effect of topographic features with relatively large or sudden changes in elevation. Two benchmark cases are studied for computational fluid dynamics (CFD) model evaluation on smooth two-dimensional (2D) and three-dimensional (3D) hills. Thereafter, a procedure is introduced to build CFD model of a complex terrain with high terrain roughness heights (dense urban area with skyscrapers) starting from existing topography maps in order to properly extend the wind atlas data over complex terrains. CFD simulations are carried out on a 1:3000 scale model of complex topographic area using Reynolds averaged Navier–Stokes (RANS) equations along with shear stress transport (SST) k-ω turbulence model and the results are compared with the wind tunnel measurements on the same model. The study shows that CFD simulations can be successfully used in qualifying and quantifying the flow over complex topography consisting of a wide range of roughness heights, enabling to map the flow structure with very high spatial resolution.

Three-dimensional computational fluid dynamics simulation of valve-induced water hammer

2016 ◽  
Vol 231 (12) ◽  
pp. 2263-2274 ◽  
Author(s):  
Shuai Yang ◽  
Dazhuan Wu ◽  
Zhounian Lai ◽  
Tao Du
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Method Of Characteristics ◽  
Three Dimensional ◽  
Water Hammer ◽  
Dynamics Simulation ◽  
Computational Fluid Dynamics Simulation ◽  
Time Step ◽  
Obvious Effect ◽  
Simulation Results

In this study, three-dimensional computational fluid dynamics simulation was adopted to evaluate the valve-induced water hammer phenomena in a typical tank-pipeline-valve-tank system. Meanwhile, one-dimensional analysis based on method of characteristics was also used for comparison and reference. As for the computational fluid dynamics model, the water hammer event was successfully simulated by using the sliding mesh technology and considering water compressibility. The key factors affecting simulation results were investigated in detail. It is found that the size of time step has an obvious effect on the attenuation of the wave and there exists a best time step. The obtained simulation results have a good agreement with the experimental data, which shows an unquestionable advantage over the method of characteristics calculation in predicting valve-induced water hammer. In addition, the computational fluid dynamics simulation can also provide a visualization of the pressure and flow evolutions during the transient process.

scholarly journals A computational fluid dynamics simulation of liquid swallowing by impaired pharyngeal motion: bolus pathway and pharyngeal residue

2019 ◽  
Vol 317 (6) ◽  
pp. G784-G792 ◽  
Author(s):  
Jun Ohta ◽  
Shunichi Ishida ◽  
Tetsuaki Kawase ◽  
Yukio Katori ◽  
Yohsuke Imai
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Three Dimensional ◽  
Dynamics Simulation ◽  
Residual Volume ◽  
Computational Fluid Dynamics Simulation ◽  
Pharyngeal Residue ◽  
Computational Modeling And Simulation ◽  
Liquid Bolus ◽  
Thickening Agents

Common practices to improve the ability to swallow include modifying physical properties of foods and changing the posture of patients. Here, we quantified the effects of the viscosity of a liquid bolus and patient posture on the bolus pathway and pharyngeal residue using a computational fluid dynamics simulation. We developed a computational model of an impaired pharyngeal motion with a low pharyngeal pressure and no pharyngeal adaptation. We varied viscosities from 0.002 to 1 Pa·s and postures from −15° to 30° (from nearly vertical to forward leaning). In the absence of pharyngeal adaptation, a honey-like liquid bolus caused pharyngeal residue, particularly in the case of forward-leaning postures. Although the bolus speed was different among viscosities, the final pathway was only slightly different. The shape, location, and tilting of the epiglottis effectively invited a bolus to two lateral pathways, suggesting a high robustness of the swallowing process. NEW & NOTEWORTHY Thickening agents are often used for patients with dysphagia. An increase in bolus viscosity not only reduces the risk of aspiration but also can cause a residual volume in the pharynx. Because information obtained from videofluoroscopic swallowing studies is only two-dimensional, measurement of pharyngeal residue is experimentally difficult. We successfully quantified the three-dimensional bolus pathway and the pharyngeal residual volume using computational modeling and simulation.

Fluid mixing in droplet-based microfluidics with a serpentine microchannel

RSC Advances ◽  
2015 ◽  
Vol 5 (126) ◽  
pp. 104138-104144 ◽  
Author(s):  
Jiajun Wang ◽  
Jianan Wang ◽  
Lianfang Feng ◽  
Tong Lin
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Three Dimensional ◽  
Volume Of Fluid ◽  
Fluid Mixing ◽  
Dynamics Simulation ◽  
Mixing Process ◽  
Computational Fluid Dynamics Simulation ◽  
Simulation Based

The hydrodynamics and mixing process within droplets travelling along a three dimensional serpentine microchannel have been studied using a computational fluid dynamics simulation based on the volume-of-fluid approach.

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