scholarly journals Analysis of the Possibility of Using the Plain CFD Model to Simulate Two-Phase Flows in Spatial Systems of Pressure Sewer Networks

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1779
Author(s):  
Piotr Siwicki ◽  
Marcin Krukowski ◽  
Jan Studziński ◽  
Bartosz Szeląg ◽  
Rafał Wojciechowski
Keyword(s):  
Fluid Model ◽  
3D Models ◽  
Sewer System ◽  
Two Phase ◽  
Significant Deterioration ◽  
Laboratory Installation ◽  
Sewer Systems ◽  
Spatial Systems ◽  
Volume Of Fluid Model ◽  
Cfd Method

The paper analyzes the possibility of using the CFD (Computational Fluid Dynamics) method to predict the amount of sewage remaining in siphons after a full air blast of the pressure sewer system. For this purpose, the results from measurements carried out on a laboratory installation were compared with the results obtained from modelling using a spatial model (3D) and a plain model (2D) of the installation. To determine these models, the structure of the VOF (Volume of Fluid) model was used in the CFD method. The simulation calculations carried out make it possible to state that the use of the plain model with the development of the installation modelled in the plan does not result in significant deterioration of the obtained results. The possibility of using 2D models for modelling pumped sewer systems allows for a significant shortening of the calculation time, which, in practice, results in the possibility of modelling much larger and longer installations than is possible with 3D models.

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.

Experimental and Numerical Approach to Enlargement and Determination of Performance of Primary Sedimentation Basin

2007 ◽  
Author(s):  
A. M. Razmi ◽  
B. Firoozabadi
Keyword(s):  
Numerical Scheme ◽  
Fluid Model ◽  
Settling Tank ◽  
Numerical Approach ◽  
Acoustic Doppler Velocimeter ◽  
Two Phase ◽  
Optimum Position ◽  
Volume Of Fluid Model ◽  
Volume Method

In the present study, the presence of a baffle and its effect on the hydrodynamics of the flow in a primary settling tank has been investigated experimentally by ADV (Acoustic Doppler Velocimeter). On the other hand, the characteristics of this flow field were simulated by an unsteady two-phase finite volume method, and VOF (Volume of Fluid) model; and results were evaluated by the experimental data. The numerical calculation performed by using k–ε RNG model agrees well with experiments. It depicts the ability of this method in predicting the velocity profile and flow structure. In addition, the optimum position of the baffle to achieve the best performance of the tank was determined by applying the above mentioned numerical scheme.

scholarly journals Fluid Flow Control in a Billet Tundish during Steel Filling Operations

Metals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 394 ◽  
Author(s):  
Rodolfo Morales ◽  
Javier Guarneros ◽  
Kinnor Chattopadhyay ◽  
Alfonso Nájera-Bastida ◽  
Jafeth Rodríguez
Keyword(s):  
Liquid Steel ◽  
Fluid Model ◽  
Water System ◽  
Continuous Casting Of Steel ◽  
Two Phase ◽  
Computational Mesh ◽  
Mathematical Simulations ◽  
Donor Acceptor ◽  
Volume Of Fluid Model ◽  
Fluid Flow Control

The startup of casting sequences in continuous casting of steel using three different turbulence inhibitors were modeled and simulated through the multiphase volume of fluid model (VOF) in a four-strand tundish. In the actual caster, one of the inhibitors released the liquid steel with a superheat high enough to avoid freezing problems in the outer strands. A second inhibitor improved the flow, yet it yielded steel freezing in these strands. A two-phase air–water system was used to model the liquid steel–air system and the interfaces were tracked by a donor–acceptor principle applied in the computational mesh. These activities led to the design of a third inhibitor. Experimental outcomes and the mathematical simulations agreed remarkably well regarding the velocity of the stream front in the tundish floor and the mass of steel reaching the outer strands. A larger steel mass and a faster stream front helped to completely prevent the steel from freezing in the outer strands. Finally, flow fields during the filling of the tundish using two of these inhibitors were simulated and the results explain the different performances observed experimentally.

Two-Phase Flow Analysis in Multi-Channel

2004 ◽  
Author(s):  
Man Yeong Ha ◽  
Cheol Hwan Kim ◽  
Yong Won Jung ◽  
Giho Jeong ◽  
Seong Geun Heo
Keyword(s):  
Two Phase Flow ◽  
Fluid Model ◽  
Flow Analysis ◽  
Flow Characteristics ◽  
Momentum Conservation ◽  
Present Calculation ◽  
Phase Flow ◽  
Two Phase ◽  
Volume Of Fluid Model ◽  
Volume Method

In the present study, we have carried out the experimental and numerical studies for the single- and two- phase flow characteristics and the corresponding pressure drop in the single- and multi-channels. We used the finite volume method to solve the mass and momentum conservation equations. The volume of fluid model is used to predict the two-phase flow in the channel. The calculated results for the single- and two-phase flow are partly compared with the present experimental data, showing relatively good agreement between them. The numerical scheme used in this study predicts well characteristics of single- and two-phase flow in a multi-channel. Thus we expect that system performances could be improved by obtaining the optimal conditions from the present calculation.

Analytical Evaluation of Debris Cooling and Spreading Behaviors at Molten Core in Severe Accident

2014 ◽  
Author(s):  
Akihiro Kobayashi ◽  
Shuichiro Miwa ◽  
Michitsugu Mori
Keyword(s):  
Molten Metal ◽  
Nuclear Power ◽  
Fluid Model ◽  
Severe Accident ◽  
Two Phase ◽  
Temperature Dependent Viscosity ◽  
Fluid Analysis ◽  
Volume Of Fluid Model ◽  
Dependent Viscosity ◽  
Thermal Fluid Analysis

On March 11, 2011, severe accident occurred at Fukushima Daiichi Nuclear Power Plant, and Units 1 to 3 of the plant have led to core melt. That is to say, melted fuel rods and core internals fell to the bottom of the Reactor Pressure Vessel (RPV). It is also believed that molten core has leaked into the reactor containment vessel. In order to plan for a safe molten core removal from the reactor, it is important to estimate the conditions of molten core by conducting analysis. Particular importance of the analysis is to understand the mechanisms of molten core spreading-cooling processes. However, sufficient understanding of this process has not been obtained yet. The main purpose of this study is to evaluate molten metal spreading-cooling phenomena and subsequently, estimate the conditions of the molten metal. In order to achieve the purpose, the Computational Fluid Dynamics (CFD) for thermal fluid analysis, STAR-CCM+ was utilized. In the simulation of the unsteady two-phase flow, the volume of fluid model was applied for the spreading and interfacial surface formation of molten metal with the surrounding air. The key parameter for the molten metal spreading is the temperature dependent viscosity of molten metal. To assess the validity of this model, the analysis of the VULCANO VE-U7, molten metal spreading experiment, has been compared with simulation results.

scholarly journals CFD Modeling of Boiling Flow in PSBT 5×5 Bundle

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Simon Lo ◽  
Joseph Osman
Keyword(s):  
Fluid Model ◽  
Three Dimensional ◽  
Cfd Modeling ◽  
Computational Grids ◽  
Two Phase ◽  
Spacer Grids ◽  
Void Fractions ◽  
Rod Bundle ◽  
Two Fluid Model ◽  
Cfd Method

Three-dimensional computational fluid dynamics (CFD) method was used to model the boiling two-phase flow in one of the PSBT 5-by-5 rod bundle tests. The rod bundle with all the spacers was modeled explicitly using unstructured computational grids. The six-equation, two-fluid model with the wall boiling model was used to model the boiling two-phase flows in the bundle. The computed void fractions compare well with the measured data at the measuring plane. In addition to the averaged void data, the CFD results give a very detailed picture of the flow and void distributions in the bundle and how they are affected by solid structures in the flow paths such as the spacer grids and mixing vanes.

Origins and characteristics of urban wet weather pollution in combined sewer systems: the experimental urban catchment “Le Marais” in Paris

1998 ◽  
Vol 37 (1) ◽  
pp. 35-43 ◽  
Author(s):  
Marie-Christine Gromaire-Mertz ◽  
Ghassan Chebbo ◽  
Mohamed Saad
Keyword(s):  
Waste Water ◽  
Sewer System ◽  
Urban Catchment ◽  
Rainfall Events ◽  
Sources Of Pollution ◽  
Sewer Systems ◽  
Combined Sewer ◽  
Wet Weather ◽  
Wet Weather Flow ◽  
Different Sources

An experimental urban catchment has been created in the centre of Paris, in order to obtain a description of the pollution of urban wet weather flows at different levels of the combined sewer system, and to estimate the contribution of runoff, waste water and sewer sediments to this pollution. Twenty-two rainfall events were studied from May to October 1996. Dry weather flow was monitored for one week. Roof, street and yard runoff, total flow at the catchment outlet and waste water were analysed for SS, VSS, COD and BOD5, on both total and dissolved fraction. Results show an evolution in the characteristics of wet weather flow from up to downstream: concentrations increase from the catchment entry to the outlet, as well as the proportion of particle-bound pollutants and the part of organic matter. A first evaluation of the different sources of pollution establishes that a major part of wet weather flow pollution originates from inside the combined sewer, probably through erosion of sewer sediments.

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