scholarly journals A Novel Algorithm of Advection Procedure in Volume of Fluid Method to Model Free Surface Flows

2012 ◽  
Vol 2012 ◽  
pp. 1-16 ◽  
Author(s):  
M. J. Ketabdari ◽  
H. Saghi
Keyword(s):  
Free Surface ◽  
Volume Of Fluid ◽  
Free Surface Flows ◽  
Navier Stokes ◽  
Adjacent Cell ◽  
Volume Of Fluid Method ◽  
Governing Equations ◽  
Model Free ◽  
Coarse Grids ◽  
Fluid Cell

In this study, the developed procedure of advection in volume of fluid (VOF) method is presented for free surface modeling. The fluid is assumed to be incompressible and viscous and therefore, Navier-Stokes and continuity are considered as governing equations. Applying Youngs’ algorithm in staggered grids, it is assumed that fluid particles in the cell have the same velocity of the cell faces. Therefore, fluxes to neighboring cells are estimated based on cell face velocities. However, these particles can show different velocities between two adjacent cell faces. In developed model, the velocity in mass center of fluid cell is evaluated to calculate fluxes from cell faces. The performance of the model is evaluated using some alternative schemes such as translation, rotation, shear test, and dam break test. These tests showed that the developed procedure improves the results when using coarse grids. Therefore, the Modified Youngs-VOF (MYV) method is suggested as a new VOF algorithm which models the free surface problems more accurately.

A volume-of-fluid method for incompressible free surface flows

2009 ◽  
Vol 61 (12) ◽  
pp. 1331-1362 ◽  
Author(s):  
I. R. Park ◽  
K. S. Kim ◽  
J. Kim ◽  
S. H. Van
Keyword(s):  
Free Surface ◽  
Volume Of Fluid ◽  
Free Surface Flows ◽  
Volume Of Fluid Method ◽  
Surface Flows

scholarly journals Is the Volume-of-Fluid Method Coupled with a Sub-Grid Bubble Equation Efficient for Simulating Local and Continuum Aeration?

Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1535
Author(s):  
Lourenço Sassetti Mendes ◽  
Javier L. Lara ◽  
Maria Teresa Viseu
Keyword(s):  
Stokes Equations ◽  
Computational Cost ◽  
Air Entrainment ◽  
Volume Of Fluid ◽  
Free Surface Flows ◽  
Navier Stokes ◽  
Volume Of Fluid Method ◽  
Navier Stokes Equations ◽  
Engineering Standards ◽  
The One

Air entrainment is common in free surface flows in large hydraulic structures (e.g., spillways, chutes, energy dissipation structures) and must be considered to assure an effective and safe operation. Due to the large size of the prototype structures, it is infeasible to model individual air bubbles. Therefore, using the OpenFOAM toolbox, an efficient simulation model for aerated flows is developed for engineering purposes. The Reynolds-averaged Navier–Stokes equations and the volume-of-fluid method are coupled with a sub-grid bubble population model that simulates entrainment and transport. A comprehensive assessment of the effectiveness, computational cost, and reliability is performed. Local and continuum bubble entrainment are evaluated in two distinct flows: an impinging jet and along a spillway chute. Aeration is induced, respectively, by a shear flow and by the thickening of the turbulent boundary layer. Moreover, a detailed sensitivity analysis of the model’s parameters is conducted. Calibration and validation are performed against experimental and prototype data. Among the analyzed entrainment formulations, the one depending exclusively on the turbulent kinetic energy is the only applicable to different flow types. Good accuracy is found, meeting engineering standards, and the additional computation cost is marginal. Results depend primarily on the volume-of-fluid method ability to reproduce the interface. Calibration is straightforward in self-aeration but more difficult for local aeration.

Numerical Modeling of Flow Over a Dam Spillway

2006 ◽  
Author(s):  
Iraj Saeedpanah ◽  
M. Shayanfar ◽  
E. Jabbari ◽  
Mohammad Haji Mohammadi
Keyword(s):  
Free Surface ◽  
Stokes Equations ◽  
Iterative Solution ◽  
Free Surface Flows ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Continuity Equations ◽  
Water Jets ◽  
Pressure Fields ◽  
Good Agreement

Free surface flows are frequently encountered in hydraulic engineering problems including water jets, weirs and around gates. An iterative solution to the incompressible two-dimensional vertical steady Navier-Stokes equations, comprising momentum and continuity equations, is used to solve for the priori unknown free surface, the velocity and the pressure fields. The entire water body is covered by a unstructured finite element grid which is locally refined. The dynamic boundary condition is imposed for the free surface where the pressure vanishes. This procedure is done continuously until the normal velocities components vanish. To overcome numerical errors and oscillations encountering in convection terms, the SUPG (streamline upwinding Petrov-Galerkin) method is applied. The solution method is tested for different discharges onto a standard spillway geometries. The results shows good agreement with available experimental data.

An Improved Anti-Diffusive VOF Method to Predict Two-Fluid Free Surface Flows

2011 ◽  
Author(s):  
Y. G. Chen ◽  
W. G. Price ◽  
P. Temarel
Keyword(s):  
Free Surface ◽  
Diffusion Processes ◽  
Volume Fraction ◽  
Volume Of Fluid ◽  
Free Surface Flows ◽  
Vof Method ◽  
Advection Equation ◽  
Diffusion Term ◽  
Surface Flows ◽  
Two Fluid

This investigation continues the development of an anti-diffusive volume of fluid method [1] by improving accuracy through the addition of an artificial diffusion term, with a negative diffusion coefficient, to the original advection equation describing the evolution of the fluid volume fraction. The advection and diffusion processes are split into a set of two partial differential equations (PDEs). The improved anti-diffusive Volume of Fluid (VOF) method is coupled with a two-fluid flow solver to predict free surface flows and illustrated by examples given in two-dimensional flows. The first numerical example is a solitary wave travelling in a tank. The second example is a plunging wave generated by flow over a submerged obstacle of prescribed shape on a horizontal floor. The computational results are validated against available experimental data.

scholarly journals An object-oriented approach to the modelling of free-surface flows

2007 ◽  
Vol 9 (2) ◽  
pp. 81-94 ◽  
Author(s):  
V. Kutija ◽  
M. G. Murray
Keyword(s):  
Free Surface ◽  
Object Oriented ◽  
Free Surface Flows ◽  
Two Dimensions ◽  
Object Oriented Programming ◽  
Programming Approach ◽  
Engineering Practice ◽  
Surface Flows ◽  
Model Free ◽  
Novel Approach

Over the past 40 years many hydraulic modelling systems for free-surface flows have been developed and successfully used in research and engineering practice. These systems were, in general, developed using sequential programming techniques while object-oriented programming approaches have only been used in the development of their visual parts. This paper outlines the approach used in the development of the NOAH modelling systems (Newcastle Object-oriented Advanced Hydroinformatics), developed entirely within the object-oriented paradigm. This novel approach has made NOAH modelling systems computationally highly efficient and yet easy to maintain and extend. NOAH 1D and NOAH 2D are designed to model free-surface flows in one and two dimensions, respectively. NOAH 1D is based on the full de Saint-Venant equations while NOAH 2D is based on the Shallow Water equations. Beside the basic ideas behind the development of NOAH modelling systems this paper also presents their main features and discusses general benefits of the application of the object-oriented programming approach in the development of numerical codes.

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