Potential application of computational fluid dynamics to pond design

2000 ◽  
Vol 42 (10-11) ◽  
pp. 327-334 ◽  
Author(s):  
A. Shilton
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Mathematical Modelling ◽  
Potential Application ◽  
Cfd Simulation ◽  
Fluid Velocity ◽  
Three Dimensional ◽  
Small Community ◽  
Wide Range ◽  
Pond Design

The ability to reliably predict the fluid flow through a pond and relate these hydraulic characteristics to pond treatment performance would clearly be a very valuable tool to the design engineer. The application of computational fluid dynamics (CFD) mathematical modelling has the potential to do this. In recent years there has been rapid advancement of computing power and mathematical modelling software. CFD simulation gives the pond designer the potential to explore the hydraulic performance for a wide range of design configurations and scenarios. This paper reports on the application of the PHOENICS CFD package for this purpose. To demonstrate the potential application of CFD to pond design, this paper presents a series of simulations of a small community pond. The simulations undertaken were three-dimensional and incorporated the k-e turbulence model. The first of these modelled the existing pond arrangement, after which the effects of adding a baffle is shown as an example of how CFD can be applied for design. In addition to the fluid velocity field, plots of a simulated tracer slick were produced. This simulated tracer movement is used to produce hydraulic retention time distribution curves of the tracer concentration at the outlet. These are then integrated with a simple, first-order decay model for BOD removal and faecal coliform die-off to calculate treatment efficiency. This allowed direct comparison of the expected treatment efficiencies with and without the baffle modification.

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.

Computational Fluid Dynamics Study of Separated Flow Over a Three-Dimensional Axisymmetric Hill

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Varun Chitta ◽  
Tausif Jamal ◽  
D. Keith Walters
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Cfd Simulation ◽  
Three Dimensional ◽  
Separated Flow ◽  
Turbulent Shear ◽  
Turbulent Regime ◽  
Flow Transition ◽  
Mean Flow ◽  
Streamline Curvature

This paper investigates the ability of computational fluid dynamics (CFD) simulations to accurately predict the turbulent flow separating from a three-dimensional (3D) axisymmetric hill using a recently developed four-equation eddy-viscosity model (EVM). The four-equation model, denoted as k–kL–ω–v2, was developed to demonstrate physically accurate responses to flow transition, streamline curvature, and system rotation effects. The model was previously tested on several two-dimensional cases with results showing improvement in predictions when compared to other popularly available EVMs. In this paper, we present a more complex 3D application of the model. The test case is turbulent boundary layer flow with thickness δ over a hill of height 2δ mounted in an enclosed channel. The flow Reynolds number based on the hill height (ReH) is 1.3 × 105. For validation purposes, CFD simulation results obtained using the k–kL–ω–v2 model are compared with two other Reynolds-averaged Navier–Stokes (RANS) models (fully turbulent shear stress transport k–ω and transition-sensitive k–kL–ω) and with experimental data. Results obtained from the simulations in terms of mean flow statistics, pressure distribution, and turbulence characteristics are presented and discussed in detail. The results indicate that both the complex physics of flow transition and streamline curvature should be taken into account to significantly improve RANS-based CFD predictions for applications involving blunt or curved bodies in a low Re turbulent regime.

Experimental Study of Horizontal Bubble Plume With Computational Fluid Dynamics Benchmarking

2016 ◽  
Vol 138 (11) ◽  
Author(s):  
Shao-Wen Chen ◽  
Christopher Macke ◽  
Takashi Hibiki ◽  
Mamoru Ishii ◽  
Yang Liu ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Cfd Simulation ◽  
Fluid Velocity ◽  
Experimental Tests ◽  
Water Tank ◽  
Bubble Plume ◽  
Two Phase ◽  
Ansys Cfx ◽  
Computational Fluid Dynamics Cfd

In order to study the two-phase flow behaviors of a horizontal bubble plume in a tank, experimental tests along with computational fluid dynamics (CFD) simulations were carried out in this paper. An experimental facility was designed and constructed which allows air–water bubble jet being injected horizontally into a water tank by three-parallel injector nozzles with different gas and liquid superficial velocities (〈jg〉in = 2.7–5.7 m/s and 〈jf〉in = 1.8–3.4 m/s). Two sizes of injector nozzles (D = 0.053 m and 0.035 m) were tested to examine the injector size effect. Important parameters including void fraction, fluid velocity, bubble Sauter mean diameter, and their distributions in the tank were measured and analyzed. In addition to the experimental work, selected flow conditions were simulated with ANSYS CFX 13.0. Compared with the experimental data, the present CFD simulation can predict the general trends of void and flow distributions and the recirculation fluid velocity with an accuracy of ±30%. The present CFD simulation methodology has been validated by the experimental results and can be applied to bubble plume analyses and design.

Application of computational fluid dynamics to predict hydrodynamic downpull on high head gates

2017 ◽  
Vol 34 (4) ◽  
pp. 1191-1203 ◽  
Author(s):  
Mete Koken ◽  
Ismail Aydin ◽  
Akis Sahin
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Numerical Models ◽  
Separation Bubble ◽  
Three Dimensional ◽  
Experimental Models ◽  
Experimental Results ◽  
Content Type ◽  
Wide Range ◽  
High Head

Purpose High head gates are commonly used in hydropower plants for flow regulation and emergence closure. Hydrodynamic downpull can be a critical parameter in design of the lifting mechanism. The purpose of this paper is to show that a simplified two-dimensional (2D) computational fluid dynamics solution can be used in the prediction of the downpull force on the gate lip by comparison of computed results to experimentally measured data. Design/methodology/approach In this study, ANSYS FLUENT CFD software was used to obtain 2D numerical solution for the flow field around a generic gate model located in a power intake structure which was previously used in an experimental study. Description of the flow domain, computational grid resolution, requirements on setting appropriate boundary conditions and methodology in describing downpull coefficient are discussed. Total number of 245 simulations for variable gate lip geometry and gate openings were run. The downpull coefficient evaluated from the computed pressure field as function of gate opening and lip angle are compared with the experimental results. Findings The computed downpull coefficient agrees well with the previous experimental results, except one gate with small lip angle where a separation bubble forms along the lip, which is responsible from this deviation. It is observed that three-dimensional (3D) effects are confined to the large gate openings where downpull is minimum or even reversed. Research limitations/implications In large gate openings, three dimensionality of the flow around gate slots plays an important role and departure from 2D solutions become more pronounced. In that case, one might need to perform a 3D solution instead. Practical implications This paper presents a very fast and accurate way to predict downpull force on high head gates in the absence of experimental data. Originality/value An extensive amount of simulations are run within the scope of this study. It is shown that knowing its limitations, 2D numerical models can be used to calculate downpull for a wide range of gate openings without the need of expensive experimental models.

scholarly journals Computational Fluid Dynamics Modeling of Rotating Annular VUV/UV Photoreactor for Water Treatment

Processes ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 79
Author(s):  
Minghan Luo ◽  
Wenjie Xu ◽  
Xiaorong Kang ◽  
Keqiang Ding ◽  
Taeseop Jeong
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Water Treatment ◽  
Cfd Modeling ◽  
Flow Mode ◽  
Oh Radicals ◽  
Dynamics Modeling ◽  
Rotational Movement ◽  
Contaminant Degradation ◽  
Wide Range

The ultraviolet photochemical degradation process is widely recognized as a low-cost, environmentally friendly, and sustainable technology for water treatment. This study integrated computational fluid dynamics (CFD) and a photoreactive kinetic model to investigate the effects of flow characteristics on the contaminant degradation performance of a rotating annular photoreactor with a vacuum-UV (VUV)/UV process performed in continuous flow mode. The results demonstrated that the introduced fluid remained in intensive rotational movement inside the reactor for a wide range of inflow rates, and the rotational movement was enhanced with increasing influent speed within the studied velocity range. The CFD modeling results were consistent with the experimental abatement of methylene blue (MB), although the model slightly overestimated MB degradation because it did not fully account for the consumption of OH radicals from byproducts generated in the MB decomposition processes. The OH radical generation and contaminant degradation efficiency of the VUV/UV process showed strong correlation with the mixing level in a photoreactor, which confirmed the promising potential of the developed rotating annular VUV reactor in water treatment.

scholarly journals Computational Fluid Dynamics (CFD) Simulation on Mixing in T-Shaped Micromixer

2020 ◽  
Vol 932 ◽  
pp. 012006
Author(s):  
S N A Ahmad Termizi ◽  
C Y Khor ◽  
M A M Nawi ◽  
Nurlela Ahmad ◽  
Muhammad Ikman Ishak ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Cfd Simulation ◽  
Computational Fluid Dynamics Cfd

A Study on the Performance of Stratified Air Conditioning Design in Assembly Halls – A Case Study at the Dazhi Cultural Center in Taiwan

2013 ◽  
Vol 368-370 ◽  
pp. 599-602 ◽  
Author(s):  
Ian Hung ◽  
Hsien Te Lin ◽  
Yu Chung Wang
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Indoor Air ◽  
Air Conditioning ◽  
Cfd Simulation ◽  
Indoor Temperature ◽  
Cultural Center ◽  
Computational Fluid Dynamics Cfd

This study focuses on the performance of air conditioning design at the Dazhi Cultural Center and uses a computational fluid dynamics (CFD) simulation to discuss the differences in wind velocity and ambient indoor temperature between all-zone air conditioning design and stratified air conditioning design. The results have strong implications for air conditioning design and can improve the indoor air quality of assembly halls.

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