CDA WorkshopPhysical & Numerical Hydraulic Modelling
STAR-CCM+ Presentation
ENGINEERING
SIMULATION
CFDFEA
Mission
Increase the competitiveness of companies
through optimization of their product
development using engineering simulation.
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 5
• Optimization/DOE
• OptiStruct
• HyperStudy
• Process
• HyperForm
• HyperXtrude
• Moldex 3D
• Post-Processing
• FieldView (CFD)
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 9
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 11
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
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
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 values23
Mesh - 0.52Hd - 2.7M
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• Base size at 15m
• Medium transition in
volume
• Surface
• 0.375m in inlet and
outlet regions
• 0.15 m in spillway
Mesh - 0.52Hd - 4.4 M
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• Base size at 15m
• Medium transition in
volume
• Surface
• 0.375m in inlet and
outlet regions
• 0.15 m in spillway
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
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 accuracy29
Case Study
1.5 X Design Head
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• Q = 601 m3/s
• Maximum elevation at
224.2 m
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
Air Entrainment at
Surface Only
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Case Study
0.52 X Design Head
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• Q = 115 m3/s
Velocity
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Velocity
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Relative Pressure
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Relative Pressure
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Froude Number
44
Turbulent Kinetic Energy
Generating Air Entrainment
45
Air Entrainment at
Surface Only
46
Questions?
Wrong BC??