Single-phase flow model development for macroscopic liquid flow evaluation in gas–liquid reactors, by computational fluid dynamics

2011 ◽  
Vol 66 (14) ◽  
pp. 3369-3376 ◽  
Author(s):  
L. Martinelli ◽  
S. Talvy ◽  
S. Liégeois ◽  
A. Vanden Berghe ◽  
Eric Chauveheid ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Liquid Flow ◽  
Single Phase ◽  
Flow Model ◽  
Model Development ◽  
Phase Flow ◽  
Single Phase Flow

scholarly journals Numerical Simulation and Analysis on Spray Drift Movement of Multirotor Plant Protection Unmanned Aerial Vehicle

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2399 ◽  
Author(s):  
Fengbo Yang ◽  
Xinyu Xue ◽  
Chen Cai ◽  
Zhu Sun ◽  
Qingqing Zhou
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Droplet Size ◽  
Wind Field ◽  
Flow Model ◽  
Two Phase Flow ◽  
Plant Protection ◽  
Three Dimensional ◽  
Phase Flow ◽  
Two Phase

In recent years, multirotor unmanned aerial vehicles (UAVs) have become more and more important in the field of plant protection in China. Multirotor unmanned plant protection UAVs have been widely used in vast plains, hills, mountains, and other regions, and become an integral part of China’s agricultural mechanization and modernization. The easy takeoff and landing performances of UAVs are urgently required for timely and effective spraying, especially in dispersed plots and hilly mountains. However, the unclearness of wind field distribution leads to more serious droplet drift problems. The drift and distribution of droplets, which depend on airflow distribution characteristics of UAVs and the droplet size of the nozzle, are directly related to the control effect of pesticide and crop growth in different growth periods. This paper proposes an approach to research the influence of the downwash and windward airflow on the motion distribution of droplet group for the SLK-5 six-rotor plant protection UAV. At first, based on the Navier-Stokes (N-S) equation and SST k–ε turbulence model, the three-dimensional wind field numerical model is established for a six-rotor plant protection UAV under 3 kg load condition. Droplet discrete phase is added to N-S equation, the momentum and energy equations are also corrected for continuous phase to establish a two-phase flow model, and a three-dimensional two-phase flow model is finally established for the six-rotor plant protection UAV. By comparing with the experiment, this paper verifies the feasibility and accuracy of a computational fluid dynamics (CFD) method in the calculation of wind field and spraying two-phase flow field. Analyses are carried out through the combination of computational fluid dynamics and radial basis neural network, and this paper, finally, discusses the influence of windward airflow and droplet size on the movement of droplet groups.

A homogeneous flow model for boiling heat transfer calculation based on single phase flow

2009 ◽  
Vol 50 (7) ◽  
pp. 1862-1868 ◽  
Author(s):  
Guo-xiang Li ◽  
Song Fu ◽  
Yun Liu ◽  
Yong Liu ◽  
Shu-zhan Bai ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Single Phase ◽  
Flow Model ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Homogeneous Flow ◽  
Heat Transfer Calculation

scholarly journals An Explicit Analytical Solution for Transient Two-Phase Flow in Inclined Fluid Transmission Lines

Fluids ◽  
2021 ◽  
Vol 6 (9) ◽  
pp. 300
Author(s):  
Taoufik Wassar ◽  
Matthew A. Franchek ◽  
Hamdi Mnasri ◽  
Yingjie Tang
Keyword(s):  
Steady State ◽  
Analytical Model ◽  
Transmission Lines ◽  
Single Phase ◽  
Flow Model ◽  
Two Phase Flow ◽  
Mechanistic Model ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Two Phase

Due to the complex nonlinearity characteristics, analytical modeling of compressible flow in inclined transmission lines remains a challenge. This paper proposes an analytical model for one-dimensional flow of a two-phase gas-liquid fluid in inclined transmission lines. The proposed model is comprised of a steady-state two-phase flow mechanistic model in-series with a dynamic single-phase flow model. The two-phase mechanistic model captures the steady-state pressure drop and liquid holdup properties of the gas-liquid fluid. The developed dynamic single-phase flow model is an analytical model comprised of rational polynomial transfer functions that are explicitly functions of fluid properties, line geometry, and inclination angle. The accuracy of the fluid resonant frequencies predicted by the transient flow model is precise and not a function of transmission line spatial discretization. Therefore, model complexity is solely a function of the number of desired modes. The dynamic single-phase model is applicable for under-damped and over-damped systems, laminar, and turbulent flow conditions. The accuracy of the overall two-phase flow model is investigated using the commercial multiphase flow dynamic code OLGA. The mean absolute error between the two models in step response overshoot and settling time is less than 8% and 2 s, respectively.

scholarly journals Numerical Simulation of a Single-Phase Flow Through Fractures with Permeable, Porous and Non-Ductile Walls

2017 ◽  
Vol 7 (5) ◽  
pp. 2041-2046
Author(s):  
N. Pour Mahmoud ◽  
A. Zabihi
Keyword(s):  
Fluid Dynamics ◽  
Numerical Simulation ◽  
Single Phase ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Surrounding Area ◽  
Fracture Geometry ◽  
Pressure Drops ◽  
Permeable Walls ◽  
Flow Through

This paper attempts to study flows within fractures through a set of numerical simulations. In addition, a special care is given to hydraulic features and characteristics of fractures. The research is performed through the application of calculative fluid dynamics and a finite volume discrete schema. The investigated flows are laminar, single-phase and stable flows of water and air through fractures with penetrable walls. The selected fracture geometry is inspired from the tomographic scan of a stone fracture. Water and air are modeled in fractures with permeable walls and different permeability levels. It has been observed that in case of permeable matrixes, the friction coefficient is lower compared to impermeable matrixes. In fact permeability reduced friction. In addition, highest pressure drops were observed in areas with smaller fracture diaphragms. Nonetheless, the surrounding area of the fracture is analyzed with the consideration of Darcy's rule.

scholarly journals Two-Phase Liquid–Liquid Flow in the Aspect of Reduction of Pumping Power of Hydrophobic Substances with High Viscosity

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2432
Author(s):  
Jerzy Hapanowicz
Keyword(s):  
Liquid Flow ◽  
Flow Resistance ◽  
Single Phase ◽  
Experimental Studies ◽  
Total Power ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Two Phase ◽  
Specific Flow ◽  
Phase Liquid

The paper reports the results of a study into a method of estimating the level of power/energy reduction needed for pumping highly viscous hydrophobic liquids. The effect of reducing the flow resistance resulting from feeding an adequate volume of water into the flow tube is considered. The polar parameters of water selected for analysis are different than oil. Experimental studies were not carried out in this regard, since the commonly accessible equation expressing the resistance of two-phase liquid–liquid flow was utilized to develop the method discussed in this study. On its basis, simulations were carried out to determine the conditions and level of reduction of the two-phase flow resistance in comparison to the single-phase flow resistance of a highly viscous oily liquid. The analysis of the results provided means for determination of such ranges of variations in the flow parameters of the two-phase liquid–liquid system, in which the total power of pumps applied to pump both liquids is smaller than the power of one pump feeding oil into the pipeline in the conditions of single-phase flow. Calculations were performed for selected constant mass flux densities of oil with various viscosities as well as for water. The proposed method can be applied in the procedure of optimization calculations for pipeline installations and their feed systems. The given example of its use was preceded by a description of the reasons and effects associated with the reduction of flow resistance in liquid–liquid systems and a detailed presentation of how to use the equation that forms the essence of the described calculation method. Attention was also paid to other phenomena accompanying two-phase liquid–liquid flows, i.e., interfacial slip, phase inversion, specific flow structures, and the viscosity of the unstable mixture of two liquids flowing in the pipe.

A computationally efficient two-phase hydro-sediment-morphdynamic model and its preliminary field applications  

2021 ◽  
Author(s):  
Binghan Lyu ◽  
Peng Hu ◽  
Ji Li ◽  
Zhixian Cao ◽  
Wei Li ◽  
...  
Keyword(s):  
Yangtze River ◽  
Single Phase ◽  
Flow Model ◽  
Two Phase Flow ◽  
Measure Data ◽  
Special Focus ◽  
Phase Flow ◽  
Computationally Efficient ◽  
Single Phase Flow ◽  
Two Phase

<p>While fluvial flows carrying relatively coarse sediments involve strong two-phase interactions, existing numerical modeling in the field-scale is mostly based on quasi-single phase flow model. Here a computationally efficient two-phase hydro-sediment-morphodynamic model is developed with a special focus on field applications. The hybrid LTS/GMaTS method originally developed for quasi-single flow model is extended to the present two-phase flow model, of which the achieved reduction in the computational cost facilitates the present field applications in the Taipingkou Waterway, Middle Yangtze River. To overcome numerical instabilities arising from the relatively large spatial and time steps in field case that lead to an issue of stiff source term, the following numerical treatments are proposed: implementation of theoretically-derived lower and upper limits for the inter-phase interactive forces. Moreover, to improve the numerical accuracy, the HLLC approximate Riemann solver is used for the water phase, whereas the FORCE solver is used for the sediment phase. Both the present two-phase flow model and the existing quasi-single-phase flow model are applied to a series of typical cases, including refilling of a dredged trench, a full dam-break flow in an abruptly widening channel and reproduction of the Taipingkou waterway, Middle Yangtze River. Compared with the quasi-single-phase flow model, the two-phase flow model has better performance as compared to the measure data and has more profound physical significance.</p>

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