Development and exploitation of a multipurpose CFD tool for optimisation of microbial reaction and sludge flow

2006 ◽  
Vol 53 (3) ◽  
pp. 101-110 ◽  
Author(s):  
T. Oda ◽  
T. Yano ◽  
Y. Niboshi
Keyword(s):  
Wastewater Treatment ◽  
Wastewater Treatment Plants ◽  
Numerical Models ◽  
Numerical Technique ◽  
Turbulence Models ◽  
Reaction Model ◽  
Experimental Results ◽  
Navier Stokes ◽  
Transfer Model ◽  
The Right

A numerical analysis technique for optimisation of microbial reaction and sludge flow has been developed in this study. The technique is based on the 3D multiphase Navier–Stokes solver with turbulence models. In order to make numerical analyses of the total processes in wastewater treatment plants possible, four numerical models, the microbial reaction model, a sludge settling model, oxygen mass transfer model from coarse bubbles, and a model from fine bubbles, are added to the solver. All parameters included in those models are calibrated in accordance with experimental results, and good agreements between calculated results and experimental results are found. Finally, this study shows that the numerical technique can be used to optimise wastewater treatment plants with an example of the operational optimisation of an intermittent agitation in anoxic reactors by coarse bubbles. With a proper appreciation of its limit and advantages, the exploitation of the CFD efficiently leads us to the right direction even though it is not quantitatively perfect.

scholarly journals An Investigation of Turbulence Modelling in Transonic Fans Including a Novel Implementation of an Implicit κ–ϵ Turbulence Model

1992 ◽  
Author(s):  
Mark G. Turner ◽  
Ian K. Jennions
Keyword(s):  
Turbulence Models ◽  
Algebraic Model ◽  
Turbulence Modelling ◽  
Experimental Results ◽  
Navier Stokes ◽  
Multiple Time Scales ◽  
Multiple Time ◽  
Wall Functions ◽  
Solution Methods ◽  
Explicit Solver

An explicit Navier-Stokes solver has been written with the option of using one of two types of turbulence models. One is the Baldwin-Lomax algebraic model and the other is an implicit k-ϵ model which has been coupled with the explicit Navier-Stokes solver in a novel way. This type of coupling, which uses two different solution methods, is unique and combines the overall robustness of the implicit k-ϵ solver with the simplicity of the explicit solver. The resulting code has been applied to the solution of the flow in a transonic fan rotor which has been experimentally investigated by Wennerstrom. Five separate solutions, each identical except for the turbulence modelling details, have been obtained and compared with the experimental results. The five different turbulence models run were: the standard Baldwin-Lomax model both with and without wall functions, the Baldwin-Lomax model with modified constants and wall functions, a standard k-ϵ model and an extended k-ϵ model which accounts for multiple time scales by adding an extra term to the dissipation equation. In general, as the model includes more of the physics, the computed shock position becomes closer to the experimental results.

New Insight Into the Flow Around a Wind Turbine Airfoil Section1

2005 ◽  
Vol 127 (2) ◽  
pp. 214-222 ◽  
Author(s):  
F. Bertagnolio ◽  
N. N. Sørensen ◽  
F. Rasmussen
Keyword(s):  
Wind Turbine ◽  
Numerical Models ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Unsteady Aerodynamics ◽  
Turbulence Models ◽  
Navier Stokes ◽  
Detached Eddy Simulation ◽  
Pitching Airfoil ◽  
Wind Turbine Airfoil

The objective of this paper is an improved understanding of the physics of the aeroelastic motion of wind turbine blades in order to improve the numerical models used for their design. Two- and three-dimensional Navier–Stokes calculations of the flow around a wind turbine airfoil using the k−ω SST and Detached Eddy Simulation (DES) turbulence models, as well as an engineering semiempirical dynamic stall model, are conducted. The computational results are compared to the experimental results that are available for both the static airfoil and the pitching airfoil. It is shown that the Navier–Stokes simulations can reproduce the main characteristic features of the flow. The DES model seems to be able to reproduce most of the details of the unsteady aerodynamics. Aerodynamic work computations indicate that a plunging motion of the airfoil can become unstable.

scholarly journals Numerical simulation of different turbulence models aiming at perdicting the flow and temperature separation in a Ranque-Hilsch vortex tube

2014 ◽  
Vol 18 (4) ◽  
pp. 1159-1171
Author(s):  
Hossein Azizi ◽  
Reza Saleh ◽  
Mohsen Kahrom ◽  
Reza Andalibi
Keyword(s):  
Vortex Tube ◽  
Turbulence Models ◽  
Swirl Flow ◽  
Experimental Results ◽  
Navier Stokes ◽  
Temperature Separation ◽  
Experiment Validation ◽  
Performance Curves ◽  
Mass Fractions ◽  
Flow Phenomena

A computational fluid dynamics (CFD) model is used to compare the effect of different Reynolds Averaged Navier-Stokes (RANS) based turbulence models in predicting the temperature separation and power separation in a Ranque-Hilsch vortex tube. Three first order turbulence models (standard k-?, Renormalized group RNG and shear stress transport (SST) K-? model) together with a second order numerical scheme are surveyed in the present work. The simulations are done in 2D steady, axisymetric with high swirl flow model. The performance curves (hot and cold outlet temperatures and power separation versus hot outlet mass fraction) obtained by using these turbulence models are compared with the experimental results in different cold mass fractions. The aim is to select an appropriate turbulence model for the simulation of the flow phenomena. Because of large discrepancy between 2D and experiment, validation in 3D model is also considered. The performance analysis shows that among all the turbulence models investigated in this study, temperature separation predicted by the Renormalized group RNG model is closer to the experimental results.

Experimental and Numerical Investigation of Two-Dimensional Parallel Jets

2001 ◽  
Vol 123 (2) ◽  
pp. 401-406 ◽  
Author(s):  
Elgin A. Anderson ◽  
Robert E. Spall
Keyword(s):  
Good Accuracy ◽  
Stokes Equations ◽  
Numerical Models ◽  
Symmetry Plane ◽  
Turbulence Models ◽  
Turbulent Jets ◽  
Navier Stokes ◽  
Mean Velocity ◽  
Navier Stokes Equations ◽  
The Mean

The flowfield of dual, parallel planar turbulent jets is investigated experimentally using an x-type hot-wire probe and numerically by solving the Reynolds-averaged Navier-Stokes equations. The performance of both differential Reynolds stress (RSM) and standard k-ε turbulence models is evaluated. Results show that the numerical models predict the merge and combined point characteristics to good accuracy. However, both turbulence models show a narrower width of the jet envelope than measured by experiment. The predicted profiles of the mean velocity along the symmetry plane agree well with the experimental results.

Prediction of Viscous Ship Roll Damping by Unsteady Navier-Stokes Techniques

1997 ◽  
Vol 119 (2) ◽  
pp. 108-113 ◽  
Author(s):  
R. A. Korpus ◽  
J. M. Falzarano
Keyword(s):  
Potential Flow ◽  
Turbulence Modeling ◽  
Numerical Technique ◽  
Turbulence Models ◽  
Navier Stokes ◽  
Ship Motions ◽  
Ship Hulls ◽  
Unsteady Rans ◽  
Flow Effects ◽  
Real Flow

This paper describes a numerical technique for analyzing the viscous unsteady flow around oscillating ship hulls. The technique is based on a general Reynolds-averaged Navier-Stokes (RANS) capability, and is intended to generate viscous roll moment data for the incorporation of real-flow effects into potential flow ship motions programs. The approach utilizes the finite analytic technique for discretizing the unsteady RANS equations, and a variety of advanced turbulence models for closure. The calculations presented herein focus on viscous and vortical effects without free-surface, and utilize k-epsilon turbulence modeling. Series variations are presented to study the effects of frequency, amplitude, Reynolds number, and the presence of bilge keels. Moment component breakdown studies are performed in each case to isolate the effects of viscosity, vorticity, and potential flow pressures.

A Study of Modest CFD Models for the Design of an Annular Diffuser With Struts for Swirling Flow

2008 ◽  
Author(s):  
G. K. Feldcamp ◽  
A. M. Birk
Keyword(s):  
Swirling Flow ◽  
Turbulence Models ◽  
Surface Flow ◽  
Experimental Results ◽  
Navier Stokes ◽  
Cfd Models ◽  
Pressure Distributions ◽  
Annular Diffuser ◽  
Inlet Swirl ◽  
Visualization Techniques

Cold flow experiments were conducted to study swirling flows in an annular diffuser with various strut configurations. Experimental results at 0°, 20°, and 40° of inlet swirl were obtained. Measured properties included detailed inlet and exit traverses using three and seven hole pressure probes, surface pressure taps on the diffuser wall, and surface flow visualization techniques. Evaluation of the diffuser and strut performance was based on pressure recovery, and detailed pressure distributions. The experimental results have been studied further using Reynolds Averaged Navier Stokes (RANS) based Computational Fluid Dynamics (CFD). These models are of modest size (less than four million volumes). Several turbulence models have been used to predict the performance of the annular diffuser with struts. Both high and low Reynolds number implementations of the turbulence models have been investigated. The results show that modest CFD models can be used with confidence to design these devices.

scholarly journals Overview of radiotracer experiments for better understanding of wastewater and water treatment plants in Lima (Perú)

2018 ◽  
Vol 13 (13) ◽  
pp. 85-92
Author(s):  
Carlos Sebastián Calvo
Keyword(s):  
Wastewater Treatment ◽  
Water Treatment ◽  
Wastewater Treatment Plants ◽  
Flow Behavior ◽  
Experimental Results ◽  
Water And Wastewater Treatment ◽  
Water Treatment Plants ◽  
Water And Wastewater ◽  
Different Levels

The objectives of this paper are to present an overview of possible applications of the radiotracers for better understanding of water and wastewater treatment plants. Numerous experiments have been carried out in different plants located in Lima. Four processes have been investigated: desanders, flocculators, clarifiers and digesters. Depending on the studied process, the experimental results have been interpreted at different levels of complexity: from simple troubleshooting to the modeling of the flow behavior inside the process.

scholarly journals RESEARCH ON THE EFFECTIVENESS OF AERATORS / AERATORIŲ EFEKTYVUMO TYRIMAS

2013 ◽  
Vol 6 (4) ◽  
pp. 588-592
Author(s):  
Vytenis Leonavičius
Keyword(s):  
Wastewater Treatment ◽  
Wastewater Treatment Plants ◽  
Oxidative Capacity ◽  
Biological Wastewater Treatment ◽  
Air Dispersion ◽  
Blade Tip ◽  
Flow Pressure ◽  
Flow Changes ◽  
The Right ◽  
Selection Of

In biological wastewater treatment plants, the right selection of an aerator is one of the most important elements. The choice of the aerator must take in account its performance – dissolved oxygen content per unit of energy consumed, oxidative capacity and supply of the required amount of air so that the required concentration of oxygen is saturated properly. The experiments have been conducted carefully examining the efficiency of the selected deep–cavitation aerator operating without the aerator tip or with attached two and three–blade tips. The performed investigation included air dispersion methods of opposite ejecting for determining air flow, flow pressure and dependence of vibration on different placement of the aerator under varying positions of corners. It has been established that compared to air ejecting flow, changes in pressure and vibration are most significantly influenced by a deep–cavitation aerator having a three–blade tip. Santrauka Biologiniuose nuotekų valymo įrenginiuose tinkamo aeratoriaus parinkimas yra vienas iš svarbiausių elementų. Parenkant aeratorių reikia atsižvelgti į jo darbo efektyvumą – ištirpinamą deguonies kiekį, tenkantį suvartotos energijos vienetui, oksidacinį pajėgumą ir reikiamą tiekti oro kiekį, kad būtų prisotintos nuotekos deguonimi iki reikiamos koncentracijos. Bandymai atlikti tiriant pasirinkto giluminio kavitacinio aeratoriaus veikimo efektyvumą be antgalio ir prie aeratoriaus pritvirtinus dviejų ir trijų menčių antgalius. Tyrimo metu taikant priešpriešinio srauto ežektoriaus oro dispergavimo metodus, buvo siekiama nustatyti ežektoriaus oro debitą, srauto slėgį ir vibracijos pokyčio priklausomybę nuo aeratoriaus padėties esant skirtingiems aeratoriaus statymo kampams. Nustatyta, kad lyginant pagal ežektoriaus oro debitą, slėgio ir vibracijos pokytį efektyviausiai veikia giluminis kavitacinis aeratorius su trijų menčių antgaliu.

scholarly journals Solar Fecal Coliform Disinfection in a Wastewater Treatment Plant by Oxidation Processes: Kinetic Analysis as a Function of Solar Radiation

Water ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 639
Author(s):  
Cynthia M. Núñez-Núñez ◽  
Guillermo I. Osorio-Revilla ◽  
Ignacio Villanueva-Fierro ◽  
Christian Antileo ◽  
José B. Proal-Nájera
Keyword(s):  
Wastewater Treatment ◽  
Fecal Coliform ◽  
Municipal Wastewater ◽  
Wastewater Treatment Plants ◽  
Treatment Plant ◽  
Reaction Model ◽  
Solar Disinfection ◽  
Disinfection Process ◽  
Linear Reaction ◽  
Initial Ph

The final step in the treatment of municipal wastewater is disinfection, which is required to inactivate microorganisms that have survived after treatment. Chlorine and chloramines are widely used disinfectants in wastewater treatment plants (WWTP); however, the use of chlorine as a disinfectant presents several problems. In the present research, solar disinfection and photocatalytic disinfection processes have been applied to inactivate the fecal coliform microorganisms that are present in municipal wastewater treated by activated sludge in a WWTP. A 2 × 3 × 2 factorial design was applied. The first factor was the process: solar disinfection or photocatalysis; the second was initial pH: 5, 7.5 and 9; the third was the presence or absence of a H2O2 dose of 1 mMol added at the beginning of the process. The data from experimentation were compared to predictions from different inactivation kinetic models (linear, linear + shoulder, linear + tail, Weibull and biphasic). The results show that H2O2 addition plays an important role in the process and that disinfection does not always follow a linear reaction model. When related to radiation, it becomes clear that the accumulated radiation dose, rather than the time, should be considered the most important factor in the solar disinfection process.

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