scholarly journals Hydrodynamic characteristics of lateral withdrawal with effects of the slope ratio

2021 ◽  
Author(s):  
Wen-long Zhao ◽  
Jian Zhang ◽  
Wei He ◽  
Tian-xiang Zhang ◽  
Shan Wang ◽  
...  
Keyword(s):  
Secondary Flow ◽  
Fluid Model ◽  
Experimental Tests ◽  
Water Transfer ◽  
Hydrodynamic Characteristics ◽  
Stable Operation ◽  
Slope Ratio ◽  
Layer Increase ◽  
Volume Of Fluid Model ◽  
Surface Vortex

Abstract Lateral withdrawal is widely performed in water transfer and water supply projects. Hydrodynamic characteristics of intake are crucial to safe and stable operation. In this study, a 3-D numerical volume of fluid model was established and validated through experimental tests. Hydrodynamic characteristics and secondary flow were investigated under scenarios with the vertical slope and different slope ratios. The helix-shaped recirculation and surface vortex are generated, and the secondary flow near the surface layer is more serious. Adding a slope ratio is beneficial to improve the flow patterns and recirculation, while the surface vortex width increases. Additionally, with the decrease in the slope ratio, recirculation width and the ratio of recirculation to the width of the layer decrease, and the minimum values are 9.19 cm and 22.97%, respectively. However, the lower the slope ratio is, the greater recirculation inhibition affects are, and the more serious the surface vortex is. With the decrease in the slope ratio, the widest surface vortex width and the ratio of the widest surface vortex to the width of the layer increase from 6.1 to 12 cm and from 7.82 to 17.14%, respectively. This research represents an advance in lateral withdrawal and provides support for further designs.

VOLUME OF FLUID MODEL FOR NUMERICAL SIMULATION OF VEGETATED FLOWS

2008 ◽  
Vol 14 (2) ◽  
pp. 72-87 ◽  
Author(s):  
Koustuv Debnath ◽  
Amartya Kumar Bhattacharya ◽  
Biswanath Mahato ◽  
Agnimitro Chakrabarti
Keyword(s):  
Numerical Simulation ◽  
Fluid Model ◽  
Volume Of Fluid ◽  
Volume Of Fluid Model

Operational Time and Melt Fraction Based Optimization of a Phase Change Material Longitudinal Fin Heat Sink

2018 ◽  
Vol 10 (6) ◽  
Author(s):  
D. Jaya Krishna
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Heat Sink ◽  
Fluid Model ◽  
Melting Behavior ◽  
Base Temperature ◽  
Critical Temperatures ◽  
Volume Of Fluid Model ◽  
Change Material ◽  
Operational Time

Abstract In the present study, the numerical investigation has been performed for a phase change material (PCM)-based longitudinal fin heat sink. The fins are taken as an integral part of the heat sink and are made up of aluminum. The PCM considered in the study is RT44HC. Heat is transferred to the heat sink through its horizontal base. In order to simulate the melting behavior of the PCM, volume of fluid model has been used. To attain the best configuration with optimum operational time, Taguchi method has been used followed by analysis of melt fraction and maximum base temperature. The optimized heat sink configuration with maximum operational time has been obtained at the critical temperatures of 54.8 °C, 63 °C, and 72.6 °C.

scholarly journals Using Splitters to Control Secondary Flow

2017 ◽  
Vol 139 (09) ◽  
pp. 58-59
Author(s):  
C. Clark ◽  
G. Pullan
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Kinetic Energy ◽  
Secondary Flow ◽  
Boundary Layers ◽  
Experimental Tests ◽  
Optimization Techniques ◽  
Automated Optimization

This article elaborates the concept of splitter vanes in controlling secondary flow. Secondary flow vortices are formed by the rotation of vorticity filaments, located in the endwall boundary layers, as the filaments move through the passage. The connection between the number of stators and the secondary kinetic energy suggests that the only way to significantly reduce the mixing loss is to increase the number of blades in the row. The designs evaluated were produced with fast turn-around computational fluid dynamics (10 minutes per solution) and automated optimization techniques. Experimental tests showed that the theory was correct, and that by increasing vane count, the secondary kinetic energy was reduced by up to 80%.

scholarly journals Biphasic Computational Fluid Dynamics Modelling of the Mixture in an Agricultural Sprayer Tank

Molecules ◽  
2020 ◽  
Vol 25 (8) ◽  
pp. 1870
Author(s):  
Jorge Badules ◽  
Mariano Vidal ◽  
Antonio Boné ◽  
Emilio Gil ◽  
F. Javier García-Ramos
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Computer Simulations ◽  
Fluid Model ◽  
Standard Procedure ◽  
Theoretical Models ◽  
Physical Models ◽  
Discrete Phase Model ◽  
Discrete Phase ◽  
Volume Of Fluid Model

Agitation inside agricultural sprayer tanks can be studied while using an international standard procedure, based on obtaining internal samples of liquid. However, in practice, this test is not easy to perform. Herein, we propose the explicit study of the mixing procedure with biphasic computer simulations using Computational Fluid Dynamics (CFD). An experimental test was performed on a 3000 L tank of a commercial air-assisted sprayer, with two different agitation system configurations, in order to compare the results of several theoretical physical models of biphasic flows for CFD, both Eulerian and Lagrangian. From the analysis of these theoretical models, we conclude that the Volume of Fluid model is not viable and the Discrete Phase Model produces erroneous results, while the Eulerian and Mixture models can both be useful. However, the results obtained suggest that complex streams generated by real-world agitation systems produce more errors in calculations. Both models can be conducted in the design phase, prior to the implementation of the machine. In addition, the computer simulations allow for researchers to analyse the mixing process in detail, making it possible to evaluate the efficiency of an agitation system according to the time that is required to reach mixture homogeneity.

Computational Fluid Dynamics Applied to Bradley Hydrocyclones

2006 ◽  
Vol 530-531 ◽  
pp. 376-381 ◽  
Author(s):  
Luiz Gustavo Martins Vieira ◽  
João Jorge Ribeiro Damasceno ◽  
Marcos A.S. Barrozo
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Fluid Model ◽  
Reynolds Stress Model ◽  
Operational Conditions ◽  
Air Core ◽  
Volume Of Fluid Model ◽  
Computational Fluid Dynamics Cfd ◽  
Geometric Variables ◽  
Solid Liquid

Hydrocyclones are centrifugal devices employed on the solid-liquid and liquid-liquid separation. The operation and building of these devices are relatively simple, however the flow inside them is totally complex and its prediction is very difficult. The fluid moves on all possible directions (axial, radial and swirl), the effects of turbulence can not negligible and an air core along the center line of the hydrocyclone can appear when the operational conditions are favorable. For that reason, the most models that are used to predict the hydrocyclone performance are empirical and require the collection of the main operational and geometric variables in order to validate them. This work objectified to apply Computational Fluid Dynamics (CFD) on Bradley Hydrocyclone and compare the results from this technique to empirical models. The numerical simulation was made in a computational code called Fluent® that solves the transport equation by finite volume technique. The turbulence was described by Reynolds Stress Model (RSM) and the liquid-gas interface was treated by Volume of Fluid Model (VOF). In agreement with the results from the simulation, it was possible to predict the internal profiles of velocity, pressure, air core, particle trajectories, efficiencies, pressure drop and underflow-to-throughput ratio.

scholarly journals Hydrodynamic studies on liquid-liquid two phase flow separation in microchannel by computational fluid dynamic modelling

2021 ◽  
Vol 4 (2) ◽  
pp. first
Author(s):  
Chue Cui Ting ◽  
Afiq Mohd Laziz ◽  
Khoa Dang Dang Bui ◽  
Ngoc Thi Nhu Nguyen ◽  
Pha Ngoc Bui ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Fluid Model ◽  
Volume Of Fluid ◽  
Rapid Expansion ◽  
Separation Performance ◽  
Microfluidic Systems ◽  
Two Phase ◽  
Volume Of Fluid Model ◽  
Simulation Results ◽  
Methanol System

Microfluidic systems undergo rapid expansion of its application in different industries over the few decades as its surface tension-dominated property provides better mixing and improves mass transfer between two immiscible liquids. Synthesis of biodiesel via transesterification of vegetable oil and methanol in microfluidic systems by droplet flow requires separation of the products after the reaction occurred. The separation technique for multiphase fluid flow in the microfluidic system is different from the macro-system, as the gravitational force is overtaken by surface force. To understand these phenomena completely, a study on the hydrodynamic characteristics of two-phase oil-methanol system in microchannel was carried out. A multiphase Volume of Fluid model was developed to predict the fluid flow in the microchannel. An inline separator design was proposed along with its variable to obtain effective separation for the oil-methanol system. The separation performance was evaluated based on the amount of oil recovered and its purity. The capability of the developed model has been validated through a comparison of simulation results with published experiment. It was predicted that the purity of recovered oil was increased by more than 46% when the design with side openings arranged at both sides of the microchannel. The highest percentage recovery of oil from the mixture was simulated at 91.3% by adding the number of side openings to ensure the maximum recovery. The oil that was separated by the inline separator was predicted to be at 100% purity, which indicates that no methanol contamination throughout the separation process. The purity of the separated product can be increased by manipulating the pressure drop across the side openings. Hence, it can be concluded that the separation in a large diameter microchannel system is possible and methodology can be tuned to achieve the separation goal. Finally, the simulation results showed that the present volume of fluid model had a good agreement with the published experiment.

Physical and numerical modeling of liquid slag entrainment in mould during slabs casting

2020 ◽  
Vol 117 (5) ◽  
pp. 509
Author(s):  
Marcin Bielnicki ◽  
Jan Jowsa
Keyword(s):  
Numerical Modeling ◽  
Physical Modeling ◽  
Liquid Slag ◽  
Laboratory Experiments ◽  
Fluid Model ◽  
Submerged Entry Nozzle ◽  
Karman Vortex ◽  
Volume Of Fluid Model ◽  
Steel Slabs ◽  
Slag Entrainment

The paper presents results of physical and numerical modeling of liquid slag entrainment during continuous casting of steel slabs process. The main aim of this work was to determine the critical casting speed and also to specify, which entrainment mechanism is most responsible for transport of slag droplets into steel volume. Physical modeling was based on water-oil model of mould, made on reduced linear scale of Sl = 0.4. In mathematical modeling, Realizable k-ε and LES WALE models were used to describe turbulent motion of water and oil, whereas Volume of Fluid model was used to take into account interactions between phases. It was found, that the main cause of slag entrainment is the formation of von Karman vortex in the vicinity of submerged entry nozzle. The results of laboratory experiments and numerical simulations were compared each other. Both method are a useful tools for modeling of slag entrainment. Great agreement was found between laboratory experiments and numerical simulation carried out using LES WALE model, regarding the shape of the oil and oil entrainment as a result of vortex structures formation. However, in the simulation case using Realizable k-ε model, the oil entrainment hasn’t been modeled for the conditions under consideration.

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