Numerical Simulation for Transient Flow of Field of Water Jet Based on Euler Method

2013 ◽  
Vol 694-697 ◽  
pp. 551-554
Author(s):  
Fei Dong ◽  
Shou Chen Xing ◽  
Chen Hai Guo
Keyword(s):  
Numerical Simulation ◽  
Transient Flow ◽  
Fluid Dynamic ◽  
Dynamic Pressure ◽  
Fluid Velocity ◽  
Initial Pressure ◽  
Euler Method ◽  
Water Jet ◽  
Core Area ◽  
Two Phase

It is hard to accurately predict the shape and the characteristic of jet because of the dynamic characteristic of water jet in the atmosphere. The Eulerian model was used to calculate the water jet numerical simulation of two-phase flow. The distribution of the velocity, pressure and the component of the nozzle flow field were obtained under the condition of the initial pressure of nozzle is 100 MPa and the outlet diameter of nozzle is 0.2 mm. The results show that fluid velocity increases rapidly in the nozzle contraction section and appears the isokinetic core area after leaving the nozzle; the fluid dynamic pressure rapid rises in the nozzle contraction section and keeps invariant at the isokinetic core area; the ratio of the contraction flow radius and the nozzle radius is 7:10.

scholarly journals Flow topologies in bubble-induced turbulence: a direct numerical simulation analysis

2018 ◽  
Vol 857 ◽  
pp. 270-290 ◽  
Author(s):  
Josef Hasslberger ◽  
Markus Klein ◽  
Nilanjan Chakraborty
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Turbulent Flows ◽  
Volume Fraction ◽  
Fluid Velocity ◽  
Small Scale ◽  
Flow Topology ◽  
Two Phase ◽  
Local Flow ◽  
Interface Curvature

This paper presents a detailed investigation of flow topologies in bubble-induced two-phase turbulence. Two freely moving and deforming air bubbles that have been suspended in liquid water under counterflow conditions have been considered for this analysis. The direct numerical simulation data considered here are based on the one-fluid formulation of the two-phase flow governing equations. To study the development of coherent structures, a local flow topology analysis is performed. Using the invariants of the velocity gradient tensor, all possible small-scale flow structures can be categorized into two nodal and two focal topologies for incompressible turbulent flows. The volume fraction of focal topologies in the gaseous phase is consistently higher than in the surrounding liquid phase. This observation has been argued to be linked to a strong vorticity production at the regions of simultaneous high fluid velocity and high interface curvature. Depending on the regime (steady/laminar or unsteady/turbulent), additional effects related to the density and viscosity jump at the interface influence the behaviour. The analysis also points to a specific term of the vorticity transport equation as being responsible for the induction of vortical motion at the interface. Besides the known mechanisms, this term, related to surface tension and gradients of interface curvature, represents another potential source of turbulence production that lends itself to further investigation.

The Numerical Simulation of the Water Jet in Hydroentanglement

2011 ◽  
Vol 189-193 ◽  
pp. 2181-2184
Author(s):  
Heng Zhang ◽  
Xiao Ming Qian ◽  
Zhi Min Lu ◽  
Yuan Bai
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Multiphase Flow ◽  
Flow Model ◽  
Two Phase Flow ◽  
Water Jet ◽  
Phase Flow ◽  
Governing Equations ◽  
Two Phase ◽  
Set Up

The functions of hydroentangled nonwovens are determined by the degree of the fiber entanglement, which depend mainly on parameters of the water jet. According to the spun lacing technology, this paper set up the numerical model based on the simplified water jetting model, establishing the governing equations, and the blended two-phase flow as the multiphase flow model. This paper simulation the water needle after the water jetting from the water needle plate in the different pressure (100bar, 60bar, 45bar, 35bar).

Mass Flux and Hydrodynamic Forces of Two-Phase Cavitating Flow Through a Safety Relief Valve at Initial Subcooling Conditions

2014 ◽  
Author(s):  
Jorge Pinho ◽  
Patrick Rambaud ◽  
Saïd Chabane
Keyword(s):  
Mass Flux ◽  
Dynamic Pressure ◽  
Fluid Velocity ◽  
Flow Characteristics ◽  
Relief Valve ◽  
Two Phase ◽  
Fluid Forces ◽  
Flow Through ◽  
Phase Mixture ◽  
Local Speed

Previous experiments were conducted and reported in a safety relief valve. It was noticed that in presence of a cavitating two-phase flow, the mass flux tends to be reduced due to the two-phase mixture compressibility. Moreover, the forces acting on the valve are dependent on the dynamic pressure and therefore, characteristics may be affected by the presence of a gas phase. The goal of this study is to propose a mathematical model capable of predicting the mass flux and forces acting on a safety relief valve experiencing cavitation at initial high subcooling conditions. For the mass flux prediction, an extension of the actual recommended sizing equations of IEC 60534-2-3 is proposed, including a formulation of the semi-critical region based on the hypothesis that compressibility of a two-phase mixture may be considered as an ellipse. It is verified that at chocking flow conditions, the critical section is partially filled by vapor as the fluid velocity equals the local speed of sound. Finally, a theoretical analysis is proposed to estimate the hydrodynamic fluid forces acting on the disk of a safety relief valve, using a simplified axisymmetric system of a plate over a nozzle. Results show a good agreement against experimental data and underline the influence of the backpressure in the SRV flow characteristics.

scholarly journals Velocity difference changes between fluid and sand particles in boundary-layer and very near wake area

2021 ◽  
Vol 25 (6 Part A) ◽  
pp. 4217-4224
Author(s):  
Sha Sha ◽  
Xiantang Zhang ◽  
Zhiang Wang ◽  
Han Liu ◽  
Huiyao Zhang
Keyword(s):  
Boundary Layer ◽  
Flow Field ◽  
Cylindrical Surface ◽  
Dynamic Pressure ◽  
Fluid Velocity ◽  
Near Wake ◽  
Two Phase ◽  
Velocity Change ◽  
Sand Flow ◽  
Sand Particles

Fluent simulates the water-sand flow around a cylinder. Monitoring lines are set up at different positions in the cylindrical surface and the very near wake area behind the cylinder, in order to explore the speed difference of fluid and sand in the water-sand two-phase flow in the boundary-layer and the very near wake area. The results show that the sand particles stay for the longest time on the back of the cylindrical surface and in the very near wake area, and a small part of the sand particles are sticky on the back of the cylindrical pier. When the height of the cylinder is z/D ? (1.57, 3.14), the turbulent flow on the cylindrical surface is fully developed. The dynamic pressure of the flow field in the very near wake area be-hind the cylinder fluctuates greatly, and the water-sand flow is extremely unstable. At the monitoring position of the cylinder, there is a sudden decrease in the velocity of the fluid, while the velocity of the sand particles changes little and remains finally at about -0.02 m/s. The water-sand flow field near the wall changes drastically, but the velocity change of sand particles has obvious hysteresis compared with fluid. When leaving the near-wall position but still in the cylindrical wake area (x/D ? 3), the changes in the water-sand flow field are more intense and the velocity of the sand particles is still slightly larger than the fluid velocity.

Resin-Air Two-Phase Flow in Injection Molding Processes: An Application to Polymeric Composite Containing Embedded Metal Wires

2019 ◽  
Vol 24 ◽  
pp. 131-144
Author(s):  
T.R. Nascimento Porto ◽  
A.G. Barbosa de Lima ◽  
R. Soares Gomez ◽  
T.H. Freire de Andrade ◽  
G. Santos de Lima ◽  
...  
Keyword(s):  
Transient Flow ◽  
Fluid Dynamic ◽  
Polymeric Composite ◽  
Molding Process ◽  
Two Phase ◽  
Ansys Fluent ◽  
Steady State Condition ◽  
Resin Injection ◽  
Flow Mechanisms ◽  
Metal Wires

The development of materials with specific properties is a relevant engineering topic. The composite materials, hybrid of metal structures embedded in polymer matrices, are intensively used in mechanical systems in order to obtain materials with high resistance associated to low weight. To fabricate these materials, it is necessary to inject the polymeric resin in a liquid state in mold cavity, which characterizes a multiphase flow as the air present in the mold is repelled by strategically projected outlets. In this sense, a correct knowledge of the flow mechanisms existing in the molding process is necessary to guide the parts manufacture. Through the Ansys FLUENT® software, this work performs a mathematical modeling of the resin transient flow inside a mold where metal wires are located and presents a numerical solution that describes, through calculations of volumetric fractions, velocity and pressure fields, and the fluid dynamic aspects that characterize the liquid molding process. It has been observed that the pressure required to maintain the constant flow at the mold inlet is increased until 80s of the process, when the steady state condition is achieved, that there is a greater resistance to mold filling in the side regions close to the mold wall due to the metal wires arrangement and that the air removal velocity that occurs due to resin injection becomes very low from the moment that resin reaches the mold outlets.

Numerical Simulation of Particle-Gas Flow Through a Fixed Pipe, Using One-Way and Two-Way Coupling Methods

2016 ◽  
Vol 33 (2) ◽  
pp. 205-212 ◽  
Author(s):  
Z. Namazian ◽  
A. F. Najafi ◽  
S. M. Mousavian
Keyword(s):  
Numerical Simulation ◽  
Gas Flow ◽  
Volume Fraction ◽  
Fluid Velocity ◽  
Particle Volume Fraction ◽  
Stokes Number ◽  
Continuous Phase ◽  
Turbulent Pipe Flow ◽  
Particle Volume ◽  
Two Phase

AbstractA numerical simulation of the particle-gas flow in a vertical turbulent pipe flow was conducted. The main objective of the present article is to investigate the effects of dispersed phase (particles) on continuous phase (gas). In so doing, two general forms of Eulerian-Lagrangian approaches namely, one-way (when the fluid flow is not affected by the presence of the particles) and two-way (when the particles exert a feedback force on the fluid) couplings were used to describe the equations of motion of the two-phase flow. Gas-phase velocities which are within the order of magnitude as that of particles, volume fraction, and particle Stokes number were calculated and the results were subsequently compared with the available experimental data. The simulated results show that when the particles are added, the fluid velocity is attenuated. With an increase in particle volume fraction, particle mass loading and Stokes number, velocity attenuation also increases. Moreover, the results indicate that an increase in particle Stokes number reduces the special limited particle volume fraction, according to which one-way coupling method yields plausible results. The results have also indicated that the significance of particle fluid interaction is not merely a function of volume fraction and particle Stokes number.

Numerical Simulation of Flow Field Characteristics of Free Falling Particle Plume Affected by Particle Diameter and Density

2014 ◽  
Vol 894 ◽  
pp. 163-166 ◽  
Author(s):  
Ze Qin Liu ◽  
Ling Yu Liu ◽  
Xiao Jian Li
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Particle Density ◽  
Fluid Dynamic ◽  
Particle Diameter ◽  
Ambient Air ◽  
Two Phase ◽  
Flow Field Characteristics ◽  
Computational Fluid Dynamic Software ◽  
Free Falling

The study of flow field characteristics of free falling particle plume is part of the basic application research of gas-solid two phase flow. The Computational Fluid Dynamic Software FLUENT was adopted in this paper. The numerical simulation was carried out to study the influence of particle diameter and particle density to the particle flow field characteristics of free falling particle plume. The results of the numerical simulation showed that, with the increasing of particle diameter and the increasing of particle density, the disturbance of ambient air to the particle plume decreased, and the entrainment ability of particle plume to the ambient air was diminished.

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