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CDA Workshop Physical & Numerical Hydraulic Modelling STAR-CCM+ - - PowerPoint PPT Presentation
CDA Workshop Physical & Numerical Hydraulic Modelling STAR-CCM+ - - PowerPoint PPT Presentation
CDA Workshop Physical & Numerical Hydraulic Modelling STAR-CCM+ Presentation CFD ENGINEERING FEA SIMULATION Mission Increase the competitiveness of companies through optimization of their product development using engineering
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Mission Increase the competitiveness of companies through optimization of their product development using engineering simulation.
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Lx Sim Services
–Engineering Simulation Outsourcing –CAE-Intensive Product Design –Training
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Softwares
- CFD
– STAR-CCM+ – AcuSolve
- FEA
– HyperMesh/RADIOSS – HyperCrash – DesignLife
- MBD
– MotionSolve
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- Optimization/DOE
- OptiStruct
- HyperStudy
- Process
- HyperForm
- HyperXtrude
- Moldex 3D
- Post-Processing
- FieldView (CFD)
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Sample Projects
- DFBI - CFD
- Trim and Drag Prediction on Ship Hull
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Sample Projects
- Non-Linear FEA
- Prediction of Plastic Deformations on Frame
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Sample Projects
- Heat Transfer / Solar Radiation / Porous Baffle – CFD
- Automation of Solar Air Heater CFD
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Outline
- STAR-CCM+ Overview and Capabilities
- Modeling and simulation procedure
- Limitations and known problems
- Case Study
- Questions
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STAR-CCM+ Overview & Capabilities
- CD-adapco is the largest privately owned CFD
company
- STAR-CCM+ GUI is java based, code is C++
– Very flexible – Customization possible – Java macro system
- Finite volume method
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STAR-CCM+ Overview & Capabilities
- General purpose CFD
– Multi-Physics
- CAD package
- Multiple meshing
approaches
- Included post-processing
- Optimization
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Complete Solution from CAD to Post
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GUI Presentation
- Tree-based
management
- Graphical
window
- Output
- Properties
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Tree-Based Management
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CAD Preparation
- 3D-CAD
– Creating or modifying geometries – Similar to any sketch based package – Somewhat limited – Exposing design variables
- Operation History
– Boolean – Meshes – Adds repeatability
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Wrapper and Surface Repair
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Before After
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Meshers
- Trimmed cell
- Polyhedral
– Embedded thin
- Tetrahedral
- Prism
- Thin mesher
- Refinement
– Volume – Surfaces – Edges
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Physics
– Multiphase
- Lagrangian
- Eulerian
- VOF
- DEM
– Conjugated heat transfer – Shell modeling – Chemistry
- Combustion
- DARS
– Optimization solver – Adjoint solver
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– Electrochemistry – Electromagnetism – Overset meshes – Radiation – Aeroacoustics – Batteries – Casting – DFBI – FSI
- Solid stress
- Direct coupling
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DAM Related Models
- VOF for multiphase
- Cavitation
- Particle transport and interaction DEM
- Erosion model
- Moving parts, rotation, translation
- Multiple meshes approach
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Cons
- No aeration by default or custom
- Surface data not accessible during
calculations
- Babysitting necessary
– Tweaking of interface solvers – Mesh dependency
- Large mesh
- Long transient analysis
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Case Study – Modelling Method
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Geometry Preparation
- Create top
boundaries
- Operations to
split in 3 regions – Inlet – Spillway – Outlet
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Meshing
- Trimmed cells
– Known surface – Fast
- Mesh alignment
- Y+ between 10 and 150 targeted
- Refinement for interface
- Final mesh:
– Convergence not fully obtained – Constraint in time and CPUs
- Use of relative to base size values
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Mesh - 0.52Hd - 2.7M
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- Base size at 15m
- Medium transition in
volume
- Surface
- 0.375m in inlet and
- utlet regions
- 0.15 m in spillway
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Mesh - 0.52Hd - 4.4 M
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- Base size at 15m
- Medium transition in
volume
- Surface
- 0.375m in inlet and
- utlet regions
- 0.15 m in spillway
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Physics Model
- VOF multiphase
- Turbulent
– All y+ treatment
- Transient analysis
- Use of VOF wave to
specify reservoir levels and inlets
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Initial Conditions
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Boundary Conditions
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VOFWave Pressure
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Solver Set-Up and Convergence
- Multiple mesh approach to save computation time
- Time step 0.01s to 0.05s
– Settings available to increase accuracy for C >1 – Stability issue
- 5 iterations per time step
- Presence of oscillations in solution flow rate
– Potential mesh vs timestep problem – Choice made for time constraints vs accuracy
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Case Study 1.5 X Design Head
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- Q = 601 m3/s
- Maximum elevation at
224.2 m
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Velocity
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Velocity
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Relative Pressure
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Relative Pressure
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Froude Number
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Turbulent Kinetic Energy Generating Air Entrainment
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Air Entrainment at Surface Only
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- Creation of field functions to find location air
entrainment
- Exportation of the approximate surface
- Importation of the surface as a fluid region
- Interpolate functions on it
- Calculate aeration
- Attempted transport without success
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Air Entrainment at Surface Only
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Case Study 0.52 X Design Head
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- Q = 115 m3/s
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Velocity
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Velocity
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Relative Pressure
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Relative Pressure
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Froude Number
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Turbulent Kinetic Energy Generating Air Entrainment
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Air Entrainment at Surface Only
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Questions?
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