Computational Fluid Dynamics (CFD): What is Good CFD-Modeling Practice and What Can Be the Added Value of CFD Models to WWTP Modeling?

Batstone, Damien J.; Griborio, Alonso; Samstag, Randal W.; Wicklein, Ed; Wicks, Jeffrey D.

doi:10.2175/193864712811704161

Cited by 5 publications

(3 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, oversimplification of the CFD model and a lack of calibration will lead to errors in the simulation results and validation data. Moreover, despite the vast opportunities for the use of CFD modeling in wastewater engineering, a lack of educational support, training and targeted guidelines has been recognized as a core reason for frequent software misuse by inexperienced users (Wicklein et al, 2016), usually originating from incorrect problem statement, poor model choice, incorrect setup assumptions or misinterpretation of the results (Nopens et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Towards a robust CFD model for aeration tanks for sewage treatment – a lab-scale study

Karpinska

Bridgeman

2017

Engineering Applications of Computational Fluid Mechanics

View full text Add to dashboard Cite

Detailed insight into the hydrodynamics of aeration tanks is of crucial importance for improvements in treatment efficiency, optimization of the process design and energy-efficient operation. These factors have triggered increasing interest in the use of Computational Fluid Dynamics (CFD) to evaluate performance of wastewater treatment systems. Whilst factors such as incorrect input assumptions, poor model choice and excessive simplifications have been recognized as potential sources of output errors, there remains a need to identify the most robust strategy to faithfully simulate aeration tank performance. Therefore, the focus of this work was to undertake rigorous transient simulations of the hydrodynamics and oxygen mass transfer in a lab-scale aeration tank in order to work towards the development of robust modeling guidelines for activated sludge systems. Unlike most previous CFD analyses of aeration systems, the work reported here employed the shear stress transport (SST) k − ω turbulence model to account for the turbulent interactions between the phases inducing bubble breakup and/or coalescence, and as a consequence, promoting the formation of bubbles of different sizes and shapes. The results obtained were compared with those arising from an analysis using the standard k − ε (sk − ε) model -and assuming fixed bubble diameter-the most common CFD modeling framework used within the wastewater modeling community. Model validation was achieved using acoustic Doppler velocimetry and particle image velocimetry techniques, and experimentally derived oxygen mass transfer data. Limitations of both turbulence models used and modeling assumptions concerning bubbly flow are discussed. The benefits of the SST k − ω turbulence model are demonstrated, but the need to balance the increased computational expense of this approach compared to the sk − ε model and, indeed, bubble flow modeling are recognized. Thus, this paper presents the first rigorous analysis of turbulence model and bubble flow generation models together for activated sludge system optimization.

show abstract

Section: Introductionmentioning

confidence: 99%

Towards a robust CFD model for aeration tanks for sewage treatment – a lab-scale study

Karpinska

Bridgeman

2017

Engineering Applications of Computational Fluid Mechanics

View full text Add to dashboard Cite

show abstract

“…This approach assumes the solids follow the advective flow by coupling a separate solids transport equation (Nopens et al, ). Also, additional equations related with density state and the sludge settling velocity (usually the settling function of Vesilind () or the Takács et al ()) need to be included to achieve this coupling.…”

Section: Modeling Strategies Of Sludge Settling Processmentioning

confidence: 99%

Development and applications in computational fluid dynamics modeling for secondary settling tanks over the last three decades: A review

Gao

Stenstrom

2019

Water Environment Research

View full text Add to dashboard Cite

Secondary settling tanks (SSTs) are a crucial process that determines the performance of the activated sludge process. However, their performance is often far from satisfactory. In the last 30 years, computational fluid dynamics (CFD) has become a robust and cost-efficient tool for designing new SSTs, modifying the geometries of existing SSTs and improved control techniques in wastewater treatment plants. The first part of this review paper discusses the different approaches to model the motion of particles in SSTs. The applications of different multiphase approaches and the widely applied single-phase approach in different SST studies are reviewed. The second part reviews current CFD research and engineering practice, focusing on the formation and the effect of density currents, effects of different design variables, parameter uncertainties in modeling structures, and atmospheric conditions. Finally, challenges and future improvements of sub-models (sludge settling, rheology, turbulence, and flocculation) in the SST model framework are identified. • Practitioner points• The first journal review for the CFD applications in SSTs over the last decade. • The controversy over the relationship between SOR and SST performance can be largely explained by the prediction of the CFD model. • Density decoupling in the turbulence model is possible for well-baffled SSTs. • The relative importance of three modeling parameters is summarized. • Recommendations for future data collection are provided. • Key wordscomputational fluid dynamics; density-driven flow; secondary settling tank; wastewater treatment

show abstract

“…The effect of uniform flow distribution devices using more refined CFD models has been studied by a number of researchers and significant improvement in agreement between the model and reality has been reported [1,[12][13][14][15][16]. Park et al [3] proposed providing diffuser walls inside flow distribution channel to achieve a more uniform flow distribution.…”

Section: Introductionmentioning

confidence: 99%

Numerical method and program for computing inlet flow distribution in sedimentation tanks

Tiruneh¹,

Debessai²

2020

Math. models, eng.

View full text Add to dashboard Cite

Inlet flow distribution devices play an important role in providing uniform flow distribution in water treatment process units such as sedimentation tanks. Orifices and weirs are commonly provided along the inlet flow channels that are built across the width of sedimentation tanks. This paper presents a numerical method and computer program for computation of the inlet flow distribution over weirs and orifices. The method is based on solving a differential equation of the flow profile along the flow distribution channel using numerical technique, namely, the Runge-Kutta method. The method replaces the trial and error step employed in earlier methods in the determination of weir discharge depths. Application examples are provided in which more uniform flow distribution were achieved by employing wider channel and full tapering of the inlet flow channel geometry or through partial tapering of the ends of the channel. The method can be extended for computation of inlet flow distribution in other similar water and wastewater treatment process units that employ weirs and orifices.

show abstract

Computational Fluid Dynamics (CFD): What is Good CFD-Modeling Practice and What Can Be the Added Value of CFD Models to WWTP Modeling?

Cited by 5 publications

References 8 publications

Towards a robust CFD model for aeration tanks for sewage treatment – a lab-scale study

Towards a robust CFD model for aeration tanks for sewage treatment – a lab-scale study

Development and applications in computational fluid dynamics modeling for secondary settling tanks over the last three decades: A review

Numerical method and program for computing inlet flow distribution in sedimentation tanks

Contact Info

Product

Resources

About