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.

Numerical Simulation of Two-Phase Fluid Flow and Heat Transfer With or Without Phase Change Using a Volume-of-Fluid Model

2004 ◽  
Author(s):  
Lieke Wang ◽  
Bengt Sunde´n
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Phase Change ◽  
Fluid Model ◽  
Piecewise Linear ◽  
Volume Of Fluid ◽  
Two Phase ◽  
Flow And Heat Transfer ◽  
Vof Model ◽  
Phase Fluid

Numerical simulations of two-phase fluid flow and heat transfer with or without phase change have been carried out. The Volume-of-Fluid (VOF) model was used in the simulations, and a procedure for considering the phase change process was developed. The Piecewise Linear Interface Calculation (PLIC) method is employed for the interface reconstruction, to keep the sharp interface. The coupling between pressure and velocity is treated by the SIMPLEC algorithm. The surface tension is modeled by the Continuum Surface Force (CSF) model. An in-house code has been developed, and two examples are presented in this paper, i.e., dam-break case and a falling water droplet in a steam bath. The calculation results are compared with corresponding experimental data, and good agreement is obtained.

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

Numerical Simulation of Dense Phase Pneumatic Conveying Gypsum in Stepped Pipeline

2011 ◽  
Vol 306-307 ◽  
pp. 1387-1392
Author(s):  
Wei Xiang Wu ◽  
Zong Ming Liu ◽  
Guang Bin Duan
Keyword(s):  
Static Pressure ◽  
Fluid Model ◽  
Dynamic Pressure ◽  
Phase Flow ◽  
Pneumatic Conveying ◽  
Dense Phase ◽  
Two Phase ◽  
Simulation Results ◽  
Two Fluid Model ◽  
Two Fluid

The process of dense phase pneumatic conveying gypsum in stepped pipeline was simulated by using an Euler-Euler two fluid model of dense gas-particle two phase flow based on the kinetic theory of gas and granular. The simulation results showed dynamic pressure increased while static pressure decreased in the first two tapered pipe, but this trend became opposite in the last diffuser pipe. The gas and particle velocity both increased in the 80-65mm and 65-50mm tapered pipe, but decreased in 50-80mm diffuser pipe. In a short, the results showed that the simulation was consistent with the fact, which proved the feasibility of our simulation.

Validation of 2D CFD for Two-Phase Transient Flow in a Channel and Comparison With 1D Model

2012 ◽  
Author(s):  
Stamatis Kalogerakos ◽  
Mustapha Gourma ◽  
Chris Thompson
Keyword(s):  
Flow Regime ◽  
Slug Flow ◽  
Two Phase Flow ◽  
Fluid Model ◽  
Volume Of Fluid ◽  
Inviscid Limit ◽  
Phase Flow ◽  
Two Phase ◽  
Vof Model ◽  
Two Fluid

Severe limitations of the use of three-dimensional computational fluid dynamics codes (CFD) arise when trying to simulate multiphase flow in long pipes due to time constraints. 1D codes for two-phase flow, based on two-fluid models, are fast but are known to be accurate only when the velocities are within the Kelvin-Helmholtz inviscid limit [1]. An alternative is to carry out a two-dimensional CFD simulation of a channel based on the Volume of Fluid (VOF) model. 2D CFD has a wider applicability range compared to 1D, it does not have the issue of ill-posedness and it also has better turbulence models built in. Again compared to 1D the 2D VOF model has a better interface description and wall treatment. In this paper a novel method is introduced that allows swift simulations of pipeline two-phase flow in the stratified and slug flow regime, by approximating the pipe as a channel and with a methodology that solves the problem of the interfacial velocity differences, inherent in the volume of fluid model. An initial validation using the wave growth problem has already been carried out [2]. Here a set consisting of 92 experimental cases in the slug flow regime has been simulated with 2D CFD, and the simulation results showed a good agreement with experimental results. Discussions in the paper include also the question of the range of applicability for 2D CFD, and the advantages and disadvantages compared to 3D CFD and also to 1D code based on the two-fluid model. Shear stresses are then extracted from the 2D CFD simulations and used to recalibrate the friction factors [3] used in the 1D code.

Investigation on the function of double tipping bucket for improvement of rainfall measurement

2020 ◽  
Author(s):  
Cai Zhao ◽  
Liu Jiufu ◽  
Liu Hongwei ◽  
Liao Aimin ◽  
Liao Minhan
Keyword(s):  
Rainfall Intensity ◽  
Fluid Model ◽  
Fluid Dynamic ◽  
Systematic Errors ◽  
Rain Gauge ◽  
Water Volume ◽  
Dynamic Simulations ◽  
Mesh Method ◽  
Volume Of Fluid Model ◽  
Simulation Results

<p>The double-tipping bucket rain gauge (SL3-1) is widely used in meteorological stations to minimize the systematic errors by the influence of rainfall intensity on TBRs in China. With two tipping buckets, the upper tipping bucket turns over and injects rainwater into the converging funnel, and the lower tipping bucket can record the rainfall. In this study, CFD (computational fluid dynamic) simulations and experiments were performed to investigate the function of the double tipping bucket for TBRs in different rainfall intensity. In simulation, the volume-of-fluid model and Reynolds-averaged Navier–Stokes realizable k-ε model and dynamic mesh method were used. In experiments, electric balances, with accuracy of 0.001 g, were used to determine the water volume of the upper tipping bucket outflow. It shows that, with a converging funnel, natural precipitation is uniformed at a certain intensity around 1.9mm/min to control the rainwater outflow into blow tipping bucket to measure rainfall and reduce systematic errors caused by different precipitation intensities. Experimental results demonstrate that the outflow curve of the upper tipping bucket has high correspond with simulation results in tipping process. These results can provide knowledge of advantages of double tipping bucket rain gauge in rainfall measurement and improve the structure designs of double tipping bucket for TBRs and obtain more accurate rainfall data.</p>

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