scholarly journals Analysis of the Dynamic Characteristics of the Muzzle Flow Field and Investigation of the Influence of Projectile Nose Shape

2020 ◽  
Vol 10 (4) ◽  
pp. 1468 ◽  
Author(s):  
Ye Luo ◽  
Da Xu ◽  
Hua Li
Keyword(s):  
Flow Field ◽  
Stokes Equations ◽  
Numerical Study ◽  
Axisymmetric Flow ◽  
Numerical Algorithms ◽  
Separated Flow ◽  
Ambient Air ◽  
Navier Stokes ◽  
Dynamic Processes ◽  
Shock Interactions

In the present work, a numerical study of the dynamic processes occurring during projectile ejection from the open-end of a gun into ambient air was performed. The two-dimensional unsteady Navier–Stokes equations, assuming axisymmetric flow, were solved using an AUSM+ discrete scheme implemented with dynamic mesh boundary conditions. Five cases were carried out in the present study. First, two test cases were simulated to validate the numerical algorithms. The last three cases were used to investigate the blast flow field induced by the projectile nose shapes of flat-nosed, cone-nosed, and blunt-nosed projectiles. The study shows that some wave processes, such as shock–shock interactions, separated flow generation, and the Richtmyer–Meshkov Instability, are changed obviously with the change of projectile shape. The present study aims to deepen the understanding of the dynamic processes of unsteady muzzle flow during the projectile ejection.

scholarly journals Numerical Study of the Internal Flow Field of a Centrifugal Impeller

1994 ◽  
Author(s):  
Mou-jin Zhang ◽  
Chuan-gang Gu ◽  
Yong-miao Miao
Keyword(s):  
Flow Field ◽  
Stokes Equations ◽  
Numerical Study ◽  
Three Dimensional ◽  
Simple Algorithm ◽  
Internal Flow ◽  
Staggered Grid ◽  
Navier Stokes ◽  
Centrifugal Impeller ◽  
High Reynolds

The complex three-dimensional flow field in a centrifugal impeller with low speed is studied in this paper. Coupled with high–Reynolds–number k–ε turbulence model, the fully three–dimensional Reynolds averaged Navier–Stokes equations are solved. The Semi–Implicit Method for Pressure–Linked Equations (SIMPLE) algorithm is used. And the non–staggered grid arrangement is also used. The computed results are compared with the available experimental data. The comparison shows good agreement.

Numerical Study of Performances of Vertical Axis Tidal Turbines

2012 ◽  
Vol 455-456 ◽  
pp. 296-301
Author(s):  
Yan Liu ◽  
Peng Fei Zhao ◽  
Xiao Hui Su ◽  
Guang Zhao
Keyword(s):  
Flow Field ◽  
Turbulent Flows ◽  
Stokes Equations ◽  
Numerical Study ◽  
Vertical Axis ◽  
Negative Influence ◽  
Navier Stokes ◽  
Speed Ratio ◽  
Tidal Turbines ◽  
Central Shaft

Numerical simulations of flows over two-dimensional vertical axis tidal turbines are carried out. Unsteady Reynolds averaged Navier-Stokes Equations are applied to model turbulent flows. Influence of the central shaft and number of blades on flow field and thus performances of turbines are investigated. Performances in terms of torque and power coefficients are obtained for different types of turbines. Results demonstrates that the central shaft has a negative influence on flow field and power coefficients. Solidity and tip speed ratio are two important factors to affect turbine’s performances. This paper provides useful information for future studies.

Numerical Simulations of Flows Inside a Partially Filled Centrifuge

2003 ◽  
Vol 125 (6) ◽  
pp. 1033-1042 ◽  
Author(s):  
Fang Yan ◽  
Bakhtier Farouk
Keyword(s):  
Flow Field ◽  
Numerical Solutions ◽  
Stokes Equations ◽  
Complex Geometry ◽  
Numerical Study ◽  
Navier Stokes ◽  
Multiphase Model ◽  
Rotating Circular Cylinder ◽  
Radial Profiles ◽  
Liquid Flows

A numerical study was conducted to predict the dynamics of gas/liquid flows in a partially filled cylinder undergoing moderate to rapid rotation. Two specific problems were considered: spinup from rest of a partially filled circular container and the steady flow field in a partially filled rotating circular cylinder with an overrotating lid. Numerical solutions of the time-dependent axisymmetric Navier-Stokes equations were obtained by using a homogeneous multiphase model. The evolution of the free surface along with the flow fields in both the gas and liquid phases are predicted. The computed results were compared with available experimental data. Details of flow field structures are examined by studying the numerical solutions. Radial profiles of axial and azimuthal velocities for both the liquid and gas phases are also presented. The model developed can be used for analyzing flows and mixing problems in complex-geometry centrifuges.

scholarly journals Secondary frequencies in the wake of a circular cylinder with vortex shedding

1991 ◽  
Vol 225 ◽  
pp. 557-574 ◽  
Author(s):  
Saul S. Abarbanel ◽  
Wai Sun Don ◽  
David Gottlieb ◽  
David H. Rudy ◽  
James C. Townsend
Keyword(s):  
Circular Cylinder ◽  
Boundary Conditions ◽  
Stokes Equations ◽  
Numerical Study ◽  
Numerical Algorithms ◽  
Reynolds Numbers ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Low Reynolds Numbers ◽  
Two Dimensional Flow

A detailed numerical study of two-dimensional flow past a circular cylinder at moderately low Reynolds numbers has been conducted using three different numerical algorithms for solving the time-dependent compressible Navier–Stokes equations. It was found that if the algorithm and associated boundary conditions were consistent and stable, then the major features of the unsteady wake were well predicted. However, it was also found that even stable and consistent boundary conditions could introduce additional periodic phenomena reminiscent of the type seen in previous wind-tunnel experiments. However, these additional frequencies were eliminated by formulating the boundary conditions in terms of the characteristic variables. An analysis based on a simplified model provides an explanation for this behaviour.

Non-Reflective Boundary Conditions for a Consistent Model of Axisymmetric Electro-Magneto-Hydrodynamic Flows

1999 ◽  
Author(s):  
Hyung-Jong Ko ◽  
George S. Dulikravich
Keyword(s):  
Magnetic Fields ◽  
Flow Field ◽  
Boundary Conditions ◽  
Field Model ◽  
Stokes Equations ◽  
Constitutive Relations ◽  
Axisymmetric Flow ◽  
Navier Stokes ◽  
Electro Magnetic Field ◽  
Electro Magnetic

Abstract In this paper, the non-reflective boundary conditions for the axisymmetric electro-magneto-hydrodynamic (EMHD) flows have been derived. The electro-magneto-hydrodynamics (EMHD) deals with the motion of electrically conducting incompressible fluids under the combined influence of externally applied and internally generated electric and magnetic fields. A consistent axisymmetric EMHD flow model with linear constitutive relations and artificial compressibility was expressed in cylindrical coordinates. After some simplifications, the resulting EMHD system comprised of modified Maxwell equations for the electro-magnetic fields and modified Navier-Stokes equations for the flow-field, was transformed to a characteristic form, and the non-reflective boundary conditions were derived. The results show the strong mutual interactions between the axisymmetric flow-field and the electro-magnetic fields. The limiting cases, including the conventional axisymmetric flow-field model and the electro-magnetic field model in vacuum, are recoverable from these results.

Numerical Study on a Flow Field in the Rinsing Process of a Beverage Can Transported With a Constant Velocity

2021 ◽  
Author(s):  
Tatsuma Kawachi ◽  
Takuto Sasaki ◽  
Aya Kaneko ◽  
Yu Nishio ◽  
Takanobu Ogawa
Keyword(s):  
Flow Field ◽  
Constant Velocity ◽  
Stokes Equations ◽  
Numerical Study ◽  
Three Dimensional ◽  
Side Surface ◽  
Front Surface ◽  
Experimental Result ◽  
Navier Stokes ◽  
Navier Stokes Equations

Abstract The present study investigates the flow field in a rinsing process of a beverage can numerically and experimentally. The three-dimensional Navier-Stokes equations are solved with a finite volume method along with the volume of fluid (VOF) method for free surface. The beverage can set upside down is transported with a constant velocity and rinsed with a water jet ejected from a nozzle below the can. The case of a can at rest is also simulated. The result shows that the ejected water impinges on the can bottom and spreads along the side surface of the can. Then, as it flows down toward the can mouth, its front surface forms splashes. For the stationary can case, after the jet impinges on the can bottom, it almost evenly spreads over the side surface. The water flows downward and becomes branched flows by fingering. The time average of VOF is calculated to visualize the regions rinsed by water. For the case of a moving can, only the top region of the can is rinsed, and the ratio of the rinsed region drops to 29% from 69% for the stationary case. The computed water surfaces qualitatively agree with the experimental result, but the shape of the front surface, such as splashes and fingerings, cannot be resolved with the simulation.

Experimental and Numerical Study of Acoustic Streaming in a Cylindrical Enclosure

2005 ◽  
Author(s):  
Yiqiang Lin ◽  
Bakhtier Farouk
Keyword(s):  
Flow Field ◽  
Acoustic Waves ◽  
Stokes Equations ◽  
Numerical Study ◽  
Acoustic Streaming ◽  
Digital Camera ◽  
Sound Field ◽  
Finite Amplitude ◽  
Navier Stokes ◽  
Cylindrical Resonator

Acoustic streaming motion generated by finite-amplitude resonant oscillations in an air-filled two-dimensional cylindrical enclosure was experimentally studied and numerically simulated. The oscillatory flow field in the enclosure was created by the vibration of one end of the cylindrical resonator (L = 325 mm, R = 12.5 mm). The frequency of the wall vibration was chosen as f = 1062 Hz, such that the corresponding wavelength is equal to the length of the resonator. A standing wave was then generated in the closed tube. In the experiment, the flow field was visually studied by a smoke generator, He-Ne Laser and a digital camera. The pressure wave in the axial points was measured by a piezoresistive pressure transducer (Endvco #4428A). To simulate the flow field, the full compressible form of the Navier-Stokes equations in cylindrical coordinates was considered and solved by a highly accurate flux-corrected transport algorithm for convection terms and a central differencing scheme for the viscous and diffusive terms. In both of the experimental and numerical studies, outer acoustic streaming due to interaction of acoustic waves with viscous boundary layers was observed, and the effects of sound field intensity on the formation of streaming structures were studied.

scholarly journals Dynamics of Single Droplet Splashing on Liquid Film by Coupling FVM with VOF

Processes ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 841
Author(s):  
Yuzhen Jin ◽  
Huang Zhou ◽  
Linhang Zhu ◽  
Zeqing Li
Keyword(s):  
Liquid Film ◽  
Weber Number ◽  
Stokes Equations ◽  
Numerical Study ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Single Droplet ◽  
Navier Stokes Equations ◽  
Volume Method ◽  
The Relationship

A three-dimensional numerical study of a single droplet splashing vertically on a liquid film is presented. The numerical method is based on the finite volume method (FVM) of Navier–Stokes equations coupled with the volume of fluid (VOF) method, and the adaptive local mesh refinement technology is adopted. It enables the liquid–gas interface to be tracked more accurately, and to be less computationally expensive. The relationship between the diameter of the free rim, the height of the crown with different numbers of collision Weber, and the thickness of the liquid film is explored. The results indicate that the crown height increases as the Weber number increases, and the diameter of the crown rim is inversely proportional to the collision Weber number. It can also be concluded that the dimensionless height of the crown decreases with the increase in the thickness of the dimensionless liquid film, which has little effect on the diameter of the crown rim during its growth.

scholarly journals Experimental and Numerical Study on Water Filling and Air Expelling Process in a Pipe with Multiple Air Valves under Water Slow Filling Condition

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2511
Author(s):  
Jintao Liu ◽  
Di Xu ◽  
Shaohui Zhang ◽  
Meijian Bai
Keyword(s):  
Numerical Model ◽  
Stokes Equations ◽  
Numerical Study ◽  
Practical Method ◽  
Navier Stokes ◽  
Physical Processes ◽  
Two Phase ◽  
Saint Venant Equations ◽  
Water Filling ◽  
Air Valve

This paper investigates the physical processes involved in the water filling and air expelling process of a pipe with multiple air valves under water slow filling condition, and develops a fully coupledwater–air two-phase stratified numerical model for simulating the process. In this model, the Saint-Venant equations and the Vertical Average Navier–Stokes equations (VANS) are respectively applied to describe the water and air in pipe, and the air valve model is introduced into the VANS equations of air as the source term. The finite-volume method and implicit dual time-stepping method (IDTS) with two-order accuracy are simultaneously used to solve this numerical model to realize the full coupling between water and air movement. Then, the model is validated by using the experimental data of the pressure evolution in pipe and the air velocity evolution of air valves, which respectively characterize the water filling and air expelling process. The results show that the model performs well in capturing the physical processes, and a reasonable agreement is obtained between numerical and experimental results. This agreement demonstrates that the proposed model in this paper offers a practical method for simulating water filling and air expelling process in a pipe with multiple air valves under water slow filling condition.

On the Flow Fields of Inertial Impactors

1974 ◽  
Vol 96 (4) ◽  
pp. 394-400 ◽  
Author(s):  
V. A. Marple ◽  
B. Y. H. Liu ◽  
K. T. Whitby
Keyword(s):  
Flow Field ◽  
Stokes Equations ◽  
Relaxation Method ◽  
Water Model ◽  
Navier Stokes ◽  
Visualization Technique ◽  
Navier Stokes Equations ◽  
Theoretical Results ◽  
Plate Distance ◽  
Good Agreement

The flow field in an inertial impactor was studied experimentally with a water model by means of a flow visualization technique. The influence of such parameters as Reynolds number and jet-to-plate distance on the flow field was determined. The Navier-Stokes equations describing the laminar flow field in the impactor were solved numerically by means of a finite difference relaxation method. The theoretical results were found to be in good agreement with the empirical observations made with the water model.

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