CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba)
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CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba)

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Includes:

Includes:
1- Introduction to CFD
2- Description of the Lake
3- OpenFOAM
4- Pre-processing
5- Solving
6- Post-processing

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CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) Presentation Transcript

  • Introuduction Lake Binaba Lake Modeling Conclusion CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) Ali Abbasi Nick van de Giesen Department of Water Management Delft University of Technology November 28, 2013 Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 1/48
  • Introuduction Lake Binaba Lake Modeling Conclusion 1 Introuduction What is CFD? Why CFD? Where is CFD Used? Numerical Methods Modeling Flow Conditions 2 Lake Binaba Description Aims of the study 3 Lake Modeling CFD Model Pre-processing Solving the Flow Field Post-processing 4 Conclusion Conclusion Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 2/48
  • Introuduction Lake Binaba Lake Modeling Conclusion 1 Introuduction What is CFD? Why CFD? Where is CFD Used? Numerical Methods Modeling Flow Conditions 2 Lake Binaba Description Aims of the study 3 Lake Modeling CFD Model Pre-processing Solving the Flow Field Post-processing 4 Conclusion Conclusion Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 3/48
  • Introuduction Lake Binaba Lake Modeling Conclusion What is CFD? CFD : Computational Fluid Dynamics The result of the confluence of fluid dynamics and a range of allied subjects: Numerical Methods Grid Generation Computational Geometry Computer-aided Geometric Design Computer Graphics Parallel Computing Simulation of fluid engineering systems using modeling and numerical methods Analytical Fluid Dynamics(AFD) and Experimental Fluid Dynamics(EFD) Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 4/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Why CFD? Analysis and design: more cost effective and more rapid than EFD CFD provides high-fidelity database for diagnosting flow field Simulation of physical fluid phenomena that are difficult for experiments: full scale simulations environmental effects(wind, weather, etc.) hazards (explosions, pollution) physics (plantetary boundary layer) Knowledge and exploration of flow physics. Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 5/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Where is CFD Used? Aerospace Automotive Biomedical Hydraulics Marine Oil & Gas Power generation ... Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 6/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Where is CFD Used? Figure 1 : Smoothing the cap over a swimmer´ head significantly improves s hydrodynamic performance Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 7/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Where is CFD Used? Figure 2 : Fishway optimization: a numerical modeling study Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 8/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Where is CFD Used? Figure 3 : CFD: a valuable design tool in water resources Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 9/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Where is CFD Used? Figure 4 : CFD modeling of water flow in a basin Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 10/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Where is CFD Used? Figure 5 : Trees will reduce campus storms(Dr. Sasa Kenjere-Delta Magazine) Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 11/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Numerical Methods The continuous Initial Boundary Value Problems(IBVPs) are discretized into algebraic equations using numerical methods numerical methods include: Discretization method Solvers and numerical parameters Grid generation and transformation High performance computation(HPC) and post-processing Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 12/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Modeling Modeling is the mathematical physics problem formulation in terms of continuous initial boundary value problem(IBVPs) IBVP is in the form of Partial Differential Equations(PDEs) with appropriate boundary conditions and initial conditions. Modeling includes: Geometry and domain(simple and complex geometry, size and shape) Coordinates Governing equations Flow conditions Initial and boundary conditions select on of models for different applications Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 13/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Flow Conditions Based on the physics of the fluids phenomena, CFD can be distinguished into different categories using different criteria: Viscous vs. Inviscid (Re) External flow or Internal flow(wall bounded or not) Turbelent vs. Laminar(Re) Incompressible vs. Compressible (Ma) Single- vs. Multi-phase flow Thermal/density effects(Pr) etc. Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 14/48
  • Introuduction Lake Binaba Lake Modeling Conclusion 1 Introuduction What is CFD? Why CFD? Where is CFD Used? Numerical Methods Modeling Flow Conditions 2 Lake Binaba Description Aims of the study 3 Lake Modeling CFD Model Pre-processing Solving the Flow Field Post-processing 4 Conclusion Conclusion Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 15/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Description Lake Binaba: Location: an artificial lake located in northern Ghana Surface: the average area of the lake surface is 4.5 km 2 Average depth: only 3 m Maximum depth: 7 m Usage: a small reservoir, used as a form of infrastructure for the provision of water Air temperature: fluctuates between 24 C and 35 C Water surface temperature: varies from 28 C to 33 C Climate: (semi-)arid region Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 16/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Description Location Lake Binaba Figure 6 : Lake Binaba in Ghana Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 17/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Description Location Lake Binaba Figure 7 : Location of lake Binaba(Google earth) Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 18/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Aims of the study To develop a three-dimensional time-dependent hydrodynamic and heat transfer model(CFD model) Simulating the effects of wind and atmosphere conditions over a complex bathymetry To predict the circulation patterns as well as the temperature distribution in the water body To compute total heat storage of small shalow lakes and reservoirs in order to estimate evaporation from water surface Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 19/48
  • Introuduction Lake Binaba Lake Modeling Conclusion 1 Introuduction What is CFD? Why CFD? Where is CFD Used? Numerical Methods Modeling Flow Conditions 2 Lake Binaba Description Aims of the study 3 Lake Modeling CFD Model Pre-processing Solving the Flow Field Post-processing 4 Conclusion Conclusion Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 20/48
  • Introuduction Lake Binaba Lake Modeling Conclusion CFD Model ��� ���������� �������� �������� ������� ���� ����� ����������� ����� ����������� ������ ��������� �������� �������� ������������� ������������ ������ �������� �������� ������ �������� ������ ����� ������ ��������� ������ ����� ������ ������� ���� ������ ������ ������ ������ �������� ������ � ������������� ���������� ��������� �������� ��������� ��� ��� ���� ������ ����������������������� �� ����� ����������� ����������������� � ���� �� ��� ���� ���� ����������� ����� Figure 8 : CFD simulation workflow Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 21/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Pre-processing Main steps in preparing the bathymetry of lake to use in CFD modeling: Reading initial point cloud (x,y,z coordinates from text file) Adding extra points in point cloud to improve the generated STL file Generating the STL file Cleaning & reapairing the STL file Generating the computational mesh or CFD mesh Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 22/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Pre-processing Reading initial point cloud Reading the coordinates of points from a text file(points.asc): Figure 9 : Initial point cloud: 642 points (x,y,z) Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 23/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Pre-processing Adding extra points in point cloud to improve the generated STL file Adding extra points to define the water surface Adding extra points to improve the bathymetry Using ArcMap to interpolate between points Figure 10 : Improved point cloud: 68802 points (x,y,z)(V.S:100) Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 24/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Pre-processing Generating the STL file STL (STereoLithography) format is similar to a TIN, except it defines the shell of a volume with a set of interlocking triangular facests: facet normal ni nj outer loop vertex v1x vertex v2x vertex v3x endloop endfacet nk v1y v1z v2y v2z v3y v3z UsingMeshLab(free and open-source STL generator) Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 25/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Pre-processing Generating the STL file Figure 11 : STL file from meshLab(V.S:100) Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 26/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Pre-processing Cleaning the STL file The generated STL file should be clean to can be used in CFD modeling Using addmesh (free and open-source STL cleaner) Figure 12 : Final STL file(V.S:100) Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 27/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Pre-processing Seperating Boundaries Water surface Bottom and sides of lake Figure 13 : Final geometry used in meshing(V.S:100) Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 28/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Pre-processing Generating the computational mesh or CFD mesh Refinig the mesh near the boundaries nPoints:9,241,729; nCells:7,913,145 ∆x = 1.5m; ∆y = 1.6m; ∆z = 0.25(0.125)m Figure 14 : CFD mesh(Vertical Scale:100) Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 29/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Pre-processing Checking the mesh Generated mesh should be satisfy the criteria Figure 15 : z component of normal vector of cells(V.S:100) Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 30/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Solving the Flow Field Equations Continuity equation: ∂uj = 0, ∂xj (1) Momentum equations using Boussinesq approach ∂ui ∂ + (uj ui ) ∂t ∂xj − ∂ ∂xj − νeff ∂ui ∂uj + ∂xj ∂xi − 2 3 ∂uk ∂xk δij = (2) ∂p + gi [1 − β(T − Tref )] ∂xi Temperature in the water body ∂T ∂ ∂ ∂T + (Tuj ) − κeff ( ) = ST ∂t ∂xj ∂xk ∂xk (3) Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 31/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Solving the Flow Field Initail Conditions ICs should not affect final results Only affect the number of iterations to reach converged solution Figure 16 : Initial condition for T Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 32/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Solving the Flow Field Boundary Conditions Temperature ρ0 Cp κeff ∂T ∂z = Hnet (4) τsurf ,u = ρ0 (νt + ν) ∂u ∂z (5) τsurf ,v = ρ0 (νt + ν) ∂v ∂z (6) surf Velocity 2 2 τsurf ,u = CD ρair v10 + u10 2 2 τsurf ,v = CD ρair v10 + u10 1 2 1 2 .u10 (7) .v10 (8) Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 33/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Solving the Flow Field Meteorogical measurements 40 Tair T [C] 35 Twater−surf ace 30 25 20 15 0 10 20 30 40 50 1000 HLA HeatFluxes[W/m2 ] 800 HLW 600 Hns 400 HS HE 200 Hnet 0 Rs −200 −400 0 10 20 30 40 Time[hr] Figure 17 : Time-dependent parameters using as B.C Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 34/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Solving the Flow Field Meteorogical measurements Figure 18 : Time-dependent parameters using as B.C Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 35/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Solving the Flow Field Solver Open Source Field Operation and Manipulation (OpenFOAM) Open-Source Library Free of Charge in LINUX C++ Library Linking with PYTHON Special Issue new SOLVERS and UTILITIES Can be Created by USERS Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 36/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Solving the Flow Field Running in parallel OF runs in parallel We need to run the model in parallel Decomposing the domain accoeding to the availabe sources Using MPI OF was tested at least for 1000 cores! Using GPU Lake Binaba We are running the model on 64 and 36 nodes Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 37/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Post-processing Figure 19 : Bathymetry of lake Binaba Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 38/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Post-processing Velocity Figure 20 : Velocity in t=3930 s (V.S:10) Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 39/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Post-processing Velocity Figure 21 : Velocity in t=3930 s (V.S:10) Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 40/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Post-processing Temperature Figure 22 : Temperature in t=3930 s (V.S:10) Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 41/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Post-processing Source term in T Figure 23 : Temperature source term in t=3930 s (V.S:10) Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 42/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Post-processing Velocity Figure 24 : Velocity in t=5640 s (V.S:10) Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 43/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Post-processing Temperature Figure 25 : Temperature in t=5640 s (V.S:10) Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 44/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Post-processing Velocity Figure 26 : Velocity in t=7440 s (V.S:10) Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 45/48
  • Introuduction Lake Binaba Lake Modeling Conclusion 1 Introuduction What is CFD? Why CFD? Where is CFD Used? Numerical Methods Modeling Flow Conditions 2 Lake Binaba Description Aims of the study 3 Lake Modeling CFD Model Pre-processing Solving the Flow Field Post-processing 4 Conclusion Conclusion Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 46/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Conclusion CFD modeling and graphical output provides a detailed visual representation of the modeled system Model results provides a high degree of confidence for project owners, designers, and other stakeholders Computational fluid dynamics (CFD) analysis has proven to be a valuable design tool in the water resources Modelling is one of the best means to gain understanding of complex flow fields Wind over water surface affects lake currents, sensible and latent heat fluxes Buoyancy effect due to density gradiant in water body should be considerd in temperature profile Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 47/48
  • Introuduction Lake Binaba Lake Modeling Conclusion Thanks For your Attention Ali Abbasi — CFD Modeling of Shallow and Small Lakes (Case Study: Lake Binaba) 48/48