Extending the Meshless Local Petrov–Galerkin Method to Solve Stabilized Turbulent Fluid Flow Problems

2018 ◽  
Vol 16 (01) ◽  
pp. 1850086 ◽  
Author(s):  
Nasrin Sheikhi ◽  
Mohammad Najafi ◽  
Vali Enjilela
Keyword(s):  
Fluid Flow ◽  
Turbulent Flow ◽  
Galerkin Method ◽  
Standard Test ◽  
Test Cases ◽  
Turbulent Fluid Flow ◽  
Turbulent Fluid ◽  
Flow Problems ◽  
Laminar And Turbulent Flow ◽  
Flow Through

The aim of this paper is to extend the meshless local Petrov–Galerkin method to solve stabilized turbulent fluid flow problems. For the unsteady incompressible turbulent fluid flow problems, the Spalart–Allmaras model is used to stabilize the governing equations, and the meshless local Petrov–Galerkin method is extended based on the vorticity-stream function to solve the turbulent flow problems. In this study, the moving least squares scheme interpolates the field variables. The proposed method solves three standard test cases of the turbulent flow over a flat plate, turbulent flow through a channel, and turbulent flow over a backward-facing step for evaluation of the method’s capability, accuracy, and validity purposes. Based on the comparison of the three test cases results with those of the experimental and conventional numerical works available in the literature, the proposed method shows to be accurate and quite implemental. The new extended method in this study together with the previously published works of the authors (on extending the meshless local Petrov–Galerkin method to solve laminar flow problems) now, for the first time, empower the meshless method to solve both laminar and turbulent flow problems.

scholarly journals Accessing the Influence of Hess-Murray Law on Suspension Flow through Ramified Structures

2013 ◽  
Vol 334-335 ◽  
pp. 322-328 ◽  
Author(s):  
Ana Serrenho ◽  
Antonio F. Miguel
Keyword(s):  
Fluid Flow ◽  
Turbulent Flow ◽  
Cross Section ◽  
Particle Transport ◽  
Flow Resistance ◽  
Suspension Flow ◽  
Similar Performance ◽  
Particle Penetration ◽  
Laminar And Turbulent Flow ◽  
Flow Through

The present study focuses on fluid flow and particle transport in symmetric T-shaped structures formed by tubes with circular and square cross-section. The performances of optimized structures (i.e., structures designed based on constructal allometric laws for minimum flow resistance) and not optimized structures were studied. Flow resistance and particle penetration efficiency were studied both for laminar and turbulent flow regimes, and for micrometer and submicrometer particles. Optimized structures have been proven to perform better for fluid flow but they have a similar performance for particle transport.

scholarly journals An examination of turbulent flow with an ultramicroscope

1932 ◽  
Vol 135 (828) ◽  
pp. 656-677 ◽  
Keyword(s):  
Fluid Flow ◽  
Turbulent Flow ◽  
Flow Pattern ◽  
Wave Length ◽  
Turbulent Fluid Flow ◽  
Turbulent Fluid ◽  
Dark Background ◽  
Internal Motions ◽  
Ordinary Light

1. Hitherto, the majority of researches into the character of turbulent fluid flow have been concerned with the motions of relatively large molar masses of fluid, and the methods used to obtain visual impressions of the flow pattern have usually involved the introduction into the fluid of particles of extraneous matter, such as aluminium particles, oil drops, etc. It is questionable whether such methods are permissible for the examination of microturbulence, especially near the boundary of the fluid where the scale of the turbulence is small, since if the particles introduced are comparable in size with the molar masses, their internal motions may not be faithfully represented. In a study of this kind of motion it is very desirable therefore to avoid any such interference with the flow, and the ultramicroscope offered a possible means of doing this provided the difficulties in applying the instrument could be surmounted. 2. The principle of the ultramicroscope depends on the fact that minute particles usually present in most fluids, but invisible in ordinary light even under the most powerful microscope, become visible when intensely illuminated provided they are seen against a dark background. Particles whose shapes are not discernible, because they are smaller than the wave-length of light, then become visible as bright points of light.

Contribution of Fluctuating Large-Scale Motions in Turbulent Fluid Flow Through a Channel

2019 ◽  
Author(s):  
Yoichi Mito
Keyword(s):  
Fluid Flow ◽  
Large Scale ◽  
Wall Turbulence ◽  
Small Scale ◽  
Large Contribution ◽  
Turbulent Fluid Flow ◽  
Turbulent Fluid ◽  
Fluid Turbulence ◽  
Turbulence Structures ◽  
Flow Through

Abstract The key mechanism that sustains fluid turbulence flowing through a channel is examined using the Lagrangian experiment, done in a direct numerical simulation (DNS) of the turbulent fluid flow and that being damped by addition of a small amount of small particles. The results indicate large contribution of the fluctuations of large-scale fluid motions, which are seen as their multi-directionality and multi-dimensionality, to sustenance of wall turbulence. Small-scale fluid turbulence structures, such as vortices and packets of them, are seen to induce the fluctuations of large-scale fluid motions.

Simulation of Multiphase Turbulent Fluid Flow Through an Electrolytic Cell

2003 ◽  
Author(s):  
Roald Akberov ◽  
Valery Ponyavin ◽  
Yitung Chen ◽  
Hsuan-Tsung Hsieh ◽  
Darrell W. Pepper
Keyword(s):  
Fluid Flow ◽  
Electrolytic Cell ◽  
Hydrogen Gas ◽  
Solid Particles ◽  
Force Balance ◽  
Spherical Particles ◽  
Turbulent Fluid Flow ◽  
Turbulent Fluid ◽  
Flow Through ◽  
Volume Method

A Finite Volume Method was applied to a two-dimensional model for multiphase turbulent fluid flow inside an electrolytic cell. The model is based on solving the momentum equations for the single continuous liquid phase. In the model, solid particles and hydrogen gas bubbles are treated as inert spherical particles. Once the momentum equations are solved, trajectories of the particles can be calculated by integrating the force balance on the particle, which can be expressed in a Lagrangian reference frame. Turbulence is modeled via utilizing the standard k-ε model. The paper also discusses the computational meshes, which can be used for the simulation. It is shown that usage of the boundary layer type elements decreases the total number of computational nodes while maintaining the same accuracy in calculation. It is also shown that minute changes in the geometry of the cell, such as an increase in the thickness of the plate, results in obtaining more favorable flow patterns for taking solid particles away from the electrolytic cell.

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