scholarly journals An Efficient Strategy to Deliver Understanding of Both Numerical and Practical Aspects When Using Navier-Stokes Equations to Solve Fluid Mechanics Problems

Fluids ◽  
2019 ◽  
Vol 4 (4) ◽  
pp. 178 ◽  
Author(s):  
Adair ◽  
Jaeger
Keyword(s):  
Undergraduate Students ◽  
Solution Method ◽  
Stokes Equations ◽  
Numerical Approach ◽  
Navier Stokes ◽  
Governing Equations ◽  
Navier Stokes Equations ◽  
Driven Cavity ◽  
Various Boundary Conditions ◽  
Volume Method

An efficient and thorough strategy to introduce undergraduate students to a numerical approach of calculating flow is outlined. First, the basic steps, especially discretization, involved when solving Navier-Stokes equations using a finite-volume method for incompressible steady-state flow are developed with the main aim being for the students to follow through from the mathematical description of a given problem to the final solution of the governing equations in a transparent way. The well-known ‘driven-cavity’ problem is used as the problem for testing coding written by the students, and the Navier-Stokes equations are initially cast in the vorticity-streamfunction form. This is followed by moving on to a solution method using the primitive variables and discussion of details such as, closure of the Navier-Stokes equations using turbulence modelling, appropriate meshing within the computation domain, various boundary conditions, properties of fluids, and the important methods for determining that a convergence solution has been reached. Such a course is found to be an efficient and transparent approach for introducing students to computational fluid dynamics.

scholarly journals Prediction of Unsteady Natural Convection within a Square Cavity Containing an Obstacle at High Rayleigh Number Value

2015 ◽  
Vol 55 ◽  
pp. 19-26
Author(s):  
Basma Souayeh ◽  
Nader Ben Cheikh ◽  
Brahim Ben Beya ◽  
Taieb Lili
Keyword(s):  
Natural Convection ◽  
Rayleigh Number ◽  
Stokes Equations ◽  
Computer Code ◽  
Numerical Approach ◽  
Navier Stokes ◽  
Convection Flow ◽  
Square Cavity ◽  
Navier Stokes Equations ◽  
Volume Method

The present work deals with the prediction of a natural convection flow in a square cavity, partially heated by an obstacle placed at the bottom wall. The two transverse walls and the top wall of the cavity are supposed to be cold, the remaining walls are kept insulated. The main parameter of numerical investigations is the Rayleigh number (engine convection) varying from 103 to 105. When Ra is fixed at 107, the flow and thermal fields bifurcate and undergoes an unsteady behavior at critical positions. Flow patterns corresponding to the unsteady state are presented and analyzed in the current study. The simulations were conducted using a numerical approach based on the finite volume method and the projection method, which are implemented in a computer code in order to solve the Navier-Stokes equations.

scholarly journals Scale Effects on a Tip Rake Propeller Working in Open Water

2019 ◽  
Vol 7 (11) ◽  
pp. 404 ◽  
Author(s):  
Lungu
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Stokes Equations ◽  
Scale Effects ◽  
Open Water ◽  
Numerical Approach ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Conference Organization ◽  
Volume Method

The scale effect on the accuracy of a numerical simulation in ship hydrodynamics represents an important issue of the propeller numerical analysis. To grasp a better understanding on the influence of this effect, an introspection on the performances of an unconventional propeller is proposed in the present study. The paper describes an investigation of the performances of a tip rake propeller recently chosen as benchmark by the International Towing Tank Conference organization (ITTC hereafter). The numerical simulation is carried out by making use of the ISIS-CFD solver, part of the FineTM/Marine package available in the NUMECA suite. The solver is based on the finite volume method to build the spatial discretization of the governing equations. The incompressible unsteady Reynolds Averaged Navier-Stokes Equations (RANSE) are solved in a global approach. Reported solutions are compared with the experimental data provided by Schiffbau-Versuchsanstalt (SVA) Potsdam GmbH to validate the accuracy of the numerical approach. Since for the full scale the experimental data could not be possible, the ITTC’78 extrapolation method-based proposed by the SVA Potsdam has been taken as a basis for comparisons and discussions. A set of remarks will conclude the paper by providing some guidelines for further approaches in terms of the particulars of the numerics that may be further employed in similar studies.

Flow Field of XCP Probe's Head and Optimization Choice of Structural Parameters

2013 ◽  
Vol 760-762 ◽  
pp. 1753-1757
Author(s):  
Hong Kun He ◽  
Shuang Qi Yang ◽  
Guang Yu Li ◽  
Hong Min Gao
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Finite Volume Method ◽  
Stokes Equations ◽  
Structural Parameters ◽  
Navier Stokes ◽  
Governing Equations ◽  
Navier Stokes Equations ◽  
Front End ◽  
Volume Method

In this study, numerical simulation of XCP probe was executed. The 3D Navier-Stokes equations were used as governing equations, and the finite volume method combining two-equations turbulence model was applied. The flow field of XCP Probe was analyzed, especially around the XCP Probe's head. The results show that the arc design of the XCP Probe's head plays an important role on the steady falling speed. In addition, when the radian is 27°, the resistance of the probe is smallest and a larger falling speed can be achieved; The electrodes of probe should be located in front end of a conduit which is in the middle of the probe.

Numerical Model of Wave Flume

2011 ◽  
Vol 138-139 ◽  
pp. 79-84
Author(s):  
Ya Mei Lan ◽  
Yong Guo Li ◽  
Wen Hua Guo
Keyword(s):  
Stokes Equations ◽  
Navier Stokes ◽  
Volume Of Fluid Method ◽  
Governing Equations ◽  
Navier Stokes Equations ◽  
Reflected Waves ◽  
Numerical Wave Flume ◽  
Wave Flume ◽  
Computation Efficiency ◽  
Volume Method

Based on the finite volume method, the Navier-Stokes equations was used as the governing equations to develop a new module of the wave generating and absorbing function. The wave generating was introduced as the man-made source terms into the momentum equations, which was suitable for the volume of fluid method (VOF). Within the numerical wave flume, the reflected waves from the construction could be absorbed effectively. The absorbing section arranged at the end of the wave flume was for absorbing the incident wave, which allows for random and effective working time within the reletively smaller computation domain. Consequently, the computation efficiency was greatly improved. Finally, the validity of the absorbing section arranged at the front and end of the wave flume was investigated individually.

Air Flow Turbulent Fluctuations in a Centrifugal Fan

2005 ◽  
Author(s):  
F. Z. Sierra ◽  
H. C. Lara ◽  
J. Kubiak ◽  
J. Siqueiros ◽  
J. C. Garcia ◽  
...  
Keyword(s):  
Stokes Equations ◽  
Air Flow ◽  
Numerical Approach ◽  
Navier Stokes ◽  
Centrifugal Fan ◽  
Navier Stokes Equations ◽  
Turbulent Fluctuations ◽  
Operation Conditions ◽  
Fixed Parameter ◽  
Volume Method

In this work air flow turbulent fluctuations within the volute-impeller interaction region in a centrifugal fan are analyzed. The fan is part of one group of four similar units that provide the necessary air into a steam generator, in a power plant of 70 MW capacity. A numerical approach based on the finite volume method has been employed to solve the full set of Navier-Stokes equations in 3-D. Multiple reference frame was used to simulate the circular motion of the rotor inside the volute which remained static as well as the air entrance and exit sections. The whole domain was divided into 1.350 × 106 cells. Additional terms due to centrifugal and Coriolis forces were taken into account in the computation. The turbulence was addressed using one model based on renormalized group theory, RNG. Emphasis is focused on describing the velocity field within the annulus in between the rotor and the volute and its fluctuations. One first set of results indicate that the highest velocities appear in the region close to the blades tip, but they decay immediately after entering the annular volute-impeller region. Over there, the flow develops into two zones which are well defined through dynamic and static pressure contours. The results show how the magnitude of turbulence intensity varies according to different operation conditions of the fan, taking as fixed parameter the pressure at exit. The behavior of turbulence in the radial direction for a number of flow sections, starting from the cutter at the exit of the fan are examined as well.

THE NUMERICAL SIMULATION OF FLOW AROUND EJECTION SYSTEM

2009 ◽  
Vol 23 (03) ◽  
pp. 489-492
Author(s):  
DALIN ZHANG ◽  
TAO WEI
Keyword(s):  
Stokes Equations ◽  
Domain Decomposition Method ◽  
Aerodynamic Characteristics ◽  
Navier Stokes ◽  
Governing Equations ◽  
Navier Stokes Equations ◽  
Flow Mechanisms ◽  
Volume Method ◽  
Unstructured Finite Volume Method ◽  
Des Model

Aerodynamic characteristics of an Ejection Seat System at different angles of attack are studied by the numerical method and the flow mechanisms for such flows are carefully analyzed. The governing equations are Reynolds-averaged Navier-Stokes equations which are solved by the unstructured finite volume method. Upwind Osher scheme is used for spatial discretization and five-stage Runge-Kutta scheme is applied for temporal discretization. The DES model based on S-A one equation turbulence model is adopted. Parallel computation is based on the domain decomposition method and multi-block is achieved by using METIS system. The experimental data is used to validate this method. This research is helpful to understand the aerodynamic characteristics and flow mechanisms of Ejection Seat System at different angles of attack and Mach numbers, and can provide reasonable reference for Ejection Seat System design.

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.

Effect of the Separating Distance of Twin Buildings on the Generated Flow Structure

2010 ◽  
Vol 297-301 ◽  
pp. 924-929
Author(s):  
Inès Bhouri Baouab ◽  
Nejla Mahjoub Said ◽  
Hatem Mhiri ◽  
Georges Le Palec ◽  
Philippe Bournot
Keyword(s):  
Stokes Equations ◽  
Three Dimensional ◽  
Reynolds Stress Model ◽  
Navier Stokes ◽  
Wind Flow ◽  
Turbulent Model ◽  
Navier Stokes Equations ◽  
Twin Buildings ◽  
Volume Method ◽  
Numerical Examination

The present work consists in a numerical examination of the dispersion of pollutants discharged from a bent chimney and crossing twin similar cubic obstacles placed in the lee side of the source. The resulting flow is assumed to be steady, three-dimensional and turbulent. Its modelling is based upon the resolution of the Navier Stokes equations by means of the finite volume method together with the RSM (Reynolds Stress Model) turbulent model. This examination aims essentially at detailing the wind flow perturbations, the recirculation and turbulence generated by the presence of the twin cubic obstacles placed tandem at different spacing distances (gaps): W = 4 h, W = 2 h and W = 1 h where W is the distance separating both buildings.

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