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0 (hodnocen0 x )

EB

ONLINE

1st ed.

London : IWA Publishing, 2022

1 online resource (266 pages)

ISBN 9781780409030 (electronic bk.)

ISBN 9781780409023

Scientific and Technical Report Ser. ; v.28

Print version: Laurent, Julien CFD Modelling for Wastewater Treatment Processes London : IWA Publishing,c2022 ISBN 9781780409023

Cover -- Contents -- About the Chapter Authors -- JULIEN LAURENT -- INGMAR NOPENS -- RANDAL SAMSTAG -- JIM WICKS -- DAMIEN BATSTONE -- CHRISTOPHER DEGROOT -- DAVID FERNANDES DEL POZO -- ALONSO G. GRIBORIO -- RAINIER HREIZ -- ANNA M. KARPINSKA PORTELA -- OLIVIER POTIER -- USMAN REHMAN -- STEPHEN SAUNDERS -- TEWODROS MELESS TESHOME -- MARIA ELENA VALLE-MEDINA -- ED WICKLEIN -- MIN YANG -- REVIEWERS -- JAVIER CLIMENT -- NELSON MARQUES -- Preface -- Foreword -- Acknowledgements -- Chapter 1: Why CFD? -- 1.1 INTRODUCTION -- 1.2 IMPROVING HYDRAULIC DESIGN -- 1.3 OPTIMIZING TANK GEOMETRY -- 1.4 IMPROVING MODEL PREDICTIONS -- 1.5 USE FOR CALIBRATION OF SIMPLER MODELS -- 1.6 OPTIMIZE PROCESS CONTROL -- 1.7 CONCLUSIONS -- REFERENCES -- Chapter 2: Fundamentals -- 2.1 INTRODUCTION -- 2.2 GOVERNING EQUATIONS -- 2.2.1 The transport equation -- 2.2.2 The Navier-Stokes equations -- 2.2.3 Turbulence -- 2.2.3.1 Prandtl’s mixing length hypothesis -- 2.2.3.2 k-epsilon -- 2.2.3.3 Other approaches to turbulence modelling -- 2.2.4 Scalar transport -- 2.2.4.1 Solids transport -- 2.2.4.2 Heat (temperature) transport -- 2.2.4.3 Reactive CFD -- 2.2.4.4 Density couple -- equation of state -- 2.2.5 Multiphase models -- 2.2.5.1 Lagrangian approach -- 2.2.5.2 Euler-Euler approach -- 2.2.5.3 Drift flux -- 2.2.5.4 Volume-of-fluid (VOF) approach -- 2.2.5.5 Rheology models -- 2.3 NUMERICAL METHODS FOR CFD -- 2.3.1 Discretization -- 2.3.1.1 Finite difference -- 2.3.1.2 Finite element -- 2.3.1.3 Finite volume -- 2.3.1.4 Grid-less methods -- 2.3.2 Solution approaches for pressure -- 2.3.2.1 Vorticity/stream function -- 2.3.2.2 SIMPLE - semi implicit pressure linked equations -- 2.3.3 Other topics -- 2.4 GOOD MODELLING PRACTICE -- 2.4.1 Approach and key assumptions -- 2.4.2 CFD model development -- 2.4.2.1 Geometry -- 2.4.2.2 Meshing -- 2.4.2.3 Solver setup.

10.7.4 Comparison of experimental and simulated RTD.

4.3.2.4.5 Biokinetic modelling -- 4.3.2.5 Results and discussion -- 4.3.2.5.1 Comparison between the velocity measurements and the CFD model -- 4.3.2.5.2 Hydrodynamic results -- 4.3.2.5.3 CFD-biokinetic modelling results -- 4.4 RESEARCH NEEDS -- REFERENCES -- Chapter 5: High-rate algal ponds -- 5.1 INTRODUCTION -- 5.2 PROCESS DESCRIPTION -- 5.2.1 Photobioreactors -- 5.2.2 High-rate algal pond (HRAP) system -- 5.2.2.1 Geometry -- 5.2.2.2 Water level -- 5.2.2.3 Mixing -- 5.3 CFD CONCEPTS RELEVANT TO HRAP MODELLING -- 5.3.1 Momentum source -- 5.3.2 Specific boundary condition: Inlet Velocity approach -- 5.3.3 Single reference frame (SRF) -- 5.3.4 Multiple reference frame (MRF) -- 5.3.5 Moving mesh -- 5.3.6 Experimental validation -- 5.4 CASE STUDY: MODELLING A PILOT-SCALE HRAP -- 5.4.1 Geometric design of HRAP -- 5.4.2 Meshing the geometry -- 5.4.3 Solver settings and numerical simulation -- 5.4.4 Virtual tracer experiment -- 5.4.5 Results: geometrical design modifications -- 5.4.5.1 Pressure and energy consumption -- 5.4.5.2 Velocity field -- 5.4.5.3 Virtual tracer tests -- 5.4.5.4 Conclusions -- 5.5 RESEARCH NEEDS -- REFERENCES -- Chapter 6: Sedimentation -- 6.1 INTRODUCTION -- 6.2 HISTORICAL BACKGROUND -- 6.3 SLUDGE BULK FLUID MODELING OF CLARIFIERS -- 6.3.1 Primary settling -- 6.3.2 Secondary settling -- 6.4 PROCESS DESCRIPTION AND FEATURES TO BE INCLUDED IN CFD MODEL -- 6.4.1 Solids settleability -- 6.4.2 Flocculation -- 6.4.3 Fluid properties: density and rheology -- 6.4.3.1 Density -- 6.4.3.2 Sludge rheology -- 6.4.4 Hydraulic regime -- 6.4.5 Significance of biological activity -- 6.5 CFD MODELING APPROACH -- 6.5.1 Modeling simplifications -- 6.5.2 Shape and geometry -- 6.5.2.1 Inlet, outlet configurations and baffling -- 6.5.2.2 Sludge and scum withdrawal systems -- 6.5.3 Mesh and boundary conditions -- 6.5.4 Turbulence modeling.

9.4 CASE STUDIES HIGHLIGHTING THE DIFFERENT LEVELS OF VALIDATION FOR CFD MODELS -- 9.4.1 Case of a full-scale carrousel ditch -- 9.4.2 Case of a commercial ZeeWeed 500D MBR module -- 9.5 DISCUSSION -- 9.6 CONCLUSION AND RECOMMENDATIONS -- REFERENCES -- Chapter 10: How other simulation methods and digital/experimental tracer experiments can be useful for CFD with reactions -- 10.1 INTRODUCTION -- 10.2 SYSTEMIC MODELLING -- 10.2.1 Ideal reactor models -- 10.2.1.1 Continuous stirred-tank reactor (CSTR) -- 10.2.1.2 Plug-flow reactor (PFR) -- 10.2.2 Non-ideal reactor models -- 10.2.2.1 Definition of the dispersion coefficient -- 10.2.2.2 Plug-flow reactor with axial dispersion -- 10.2.2.3 Tanks-in-series -- 10.2.3 Comparison of reactors -- 10.2.4 Example of more complex systemic models -- 10.3 CFD WITH REACTIONS -- 10.3.1 Protocol -- 10.3.2 Scalar transport and reactions -- 10.4 COMPARTMENTAL MODELLING -- 10.4.1 General description -- 10.4.2 Definition -- 10.4.3 Examples -- 10.5 FUNDAMENTALS OF TRACING EXPERIMENTS AND RTD -- 10.5.1 Tracing and RTD methods -- 10.5.2 Tracing experiments -- 10.5.3 Choice of the tracer compound -- 10.5.4 Conducting the tracing experiment -- 10.5.5 Determination of the residence time distribution (RTD) -- 10.6 RESIDENCE TIME DISTRIBUTION OF CLASSIC SYSTEMIC MODELS -- 10.6.1 Ideal reactors -- 10.6.1.1 CSTR -- 10.6.1.2 Plug-flow reactor -- 10.6.2 Non-ideal reactors: taking into account dispersion -- 10.6.2.1 Plug-flow reactor with axial dispersion -- 10.6.2.2 Tank-in-series -- 10.7 TRACING EXPERIMENTS AND VIRTUAL TRACER TESTS FOR CALIBRATION OF CFD SIMULATION -- 10.7.1 Turbulent Schmidt number: pitfalls and recommendations -- 10.7.2 Virtual tracer tests in CFD -- 10.7.2.1 Scalar transport -- 10.7.2.2 Lagrangian approach -- 10.7.2.3 Choice between the two methods -- 10.7.3 Example of dispersion modelling.

2.4.2.4 Multiphase models -- 2.4.2.5 Turbulence models -- 2.4.2.6 Boundary conditions -- 2.4.2.7 Steady vs dynamic -- 2.4.3 Convergence -- 2.4.4 Calibration and validation -- REFERENCES -- Chapter 3: Hydraulic analysis and headworks -- 3.1 INTRODUCTION -- 3.2 HYDRAULIC ANALYSIS -- 3.2.1 Flow distribution -- 3.2.2 Flow splitting analysis -- 3.2.2.1 Closed conduit -- 3.2.2.2 Open channel -- 3.2.2.2.1 Fixed water surface (rigid lid) -- 3.2.2.2.2 Free surface -- 3.2.3 Hydraulic profile -- 3.2.4 Pump intakes -- 3.2.5 Outfalls -- 3.3 HEADWORKS -- 3.3.1 Screening -- 3.3.2 Grit removal -- 3.3.2.1 Case study -- 3.4 RESEARCH NEEDS -- REFERENCES -- Chapter 4: Suspended growth tanks -- 4.1 INTRODUCTION -- 4.2 LITERATURE REVIEW -- 4.2.1 Gas/liquid transfer -- 4.2.2 The importance of solids -- 4.2.3 Including biokinetics -- 4.2.4 Hybrid systems and rheology -- 4.3 CASE STUDIES -- 4.3.1 CFD modelling of a bioreactor at Eindhoven WRRF -- 4.3.1.1 Computational fluid dynamics modelling -- 4.3.1.1.1 Geometry development -- 4.3.1.1.2 Meshing -- 4.3.1.1.3 Boundary conditions -- 4.3.1.1.4 Selection of suitable models -- 4.3.1.1.5 Multiphase modelling -- 4.3.1.1.6 Turbulence modelling -- 4.3.1.1.7 Additional model considerations and convergence -- 4.3.1.2 Biokinetic modelling -- 4.3.1.3 Simulation setup -- 4.3.1.4 Validation of the velocity field -- 4.3.1.5 Results and discussion -- 4.3.1.5.1 Comparison between measurements and CFD simulations -- 4.3.1.5.2 Base case results -- 4.3.1.5.3 CFD-ASM1 results -- 4.3.2 CFD modelling of the bioreactor at La Bisbal d’Emporda WWTP -- 4.3.2.1 Configuration of the La Bisbal WWTP -- 4.3.2.2 Measurements -- 4.3.2.3 Simulation scenarios -- 4.3.2.4 Computational fluid dynamic modelling -- 4.3.2.4.1 Geometry development -- 4.3.2.4.2 Meshing -- 4.3.2.4.3 Boundary conditions -- 4.3.2.4.4 Flow and other considerations.

6.5.5 Calibration and validation of CFD results -- 6.6 CASE STUDY -- 6.7 FUTURE RESEARCH NEEDS -- REFERENCES -- Chapter 7: Disinfection -- 7.1 INTRODUCTION -- 7.2 PROCESS BACKGROUND: DISINFECTION KINETICS -- 7.3 LITERATURE REVIEW -- 7.3.1 Chemical disinfection -- 7.3.2 Ultraviolet disinfection -- 7.3.3 Hydraulic efficiency -- 7.4 CFD APPROACH -- 7.4.1 Hydraulic efficiency -- 7.5 CASE STUDIES -- 7.5.1 UV case study -- 7.5.2 Contact tank case study -- 7.6 RESEARCH NEEDS -- REFERENCES -- Chapter 8: Anaerobic digestion -- 8.1 INTRODUCTION -- 8.2 LITERATURE REVIEW -- 8.2.1 Single phase -- 8.2.2 Eulerian multiphase models -- 8.2.3 Lagrangian-based CFD modelling -- 8.2.4 Bioreactive modelling -- 8.2.5 Conclusions: literature review -- 8.3 PROCESS DESCRIPTION -- 8.3.1 Mixed digester design -- 8.3.1.1 Mixing designs -- 8.3.1.2 Mechanical mixing -- 8.3.1.3 Gas mixing -- 8.3.1.4 Gas and liquid collection systems -- 8.3.2 Plug-flow digesters -- 8.4 CFD CONCEPTS RELEVANT TO AD MODELLING -- 8.4.1 Shear rate -- 8.4.2 Non-Newtonian rheology -- 8.5 CFD APPROACH -- 8.5.1 Modelling simplifications -- 8.5.2 Eulerian multiphase approach -- 8.5.3 Geometry and mesh -- 8.5.4 Fluid properties -- 8.5.4.1 Bulk density -- 8.5.4.2 Rheological model selection -- 8.5.4.3 Numerical considerations when implementing a rheological model in CFD -- 8.5.5 Turbulence modelling -- 8.5.6 Monitoring key variables and convergence -- 8.5.7 Validation of CFD results -- 8.6 RESEARCH NEEDS -- REFERENCES -- Chapter 9: Validation -- 9.1 INTRODUCTION -- 9.2 LEVEL CLASSIFICATION OF VALIDATION FOR CFD MODELS -- 9.3 MODEL VALIDATION TECHNIQUES -- 9.3.1 Velocity measurements -- 9.3.2 Video imaging -- 9.3.3 Nuclear magnetic resonance imaging (MRI) and computed tomography (CT) scan -- 9.3.4 Electrodiffusion method (EDM) -- 9.3.5 Residence time distribution (tracer study).

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