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Outline. CFX: Advanced CFD softwareThe companyThe productsTurbulence Modells in CFXNear wall treatment in CFXExamples:Duct with adverse pressure gradientAirfoilsHeat transfer. CFX: Member of AEA Technology. CFX: Global Position. CFD (Computational Fluid Dynamics) group of AEA TechnologyLargest European CFD company210 employees8 main officesStrong industrial presenceGrowth rate approx. 25% per yearMore than 1500 installed licenses.
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1. Advanced CFD Analysis ofAerodynamics Using CFX Jorge Carregal Ferreira
Achim Holzwarth, Florian Menter
2. Outline CFX: Advanced CFD software
The company
The products
Turbulence Modells in CFX
Near wall treatment in CFX
Examples:
Duct with adverse pressure gradient
Airfoils
Heat transfer
3. CFX: Member of AEA Technology
4. CFX: Global Position CFD (Computational Fluid Dynamics) group of AEA Technology
Largest European CFD company
210 employees
8 main offices
Strong industrial presence
Growth rate approx. 25% per year
More than 1500 installed licenses
5. CFD-Analysis Generate geometry: fluid domain
Generate mesh: discrete representation of fluid domain
Solve Navier-Stokes Equiations
Analyse Results
Coupling: Optimisation, fluid-structure coupling, accoustic analysis, design improvements
6. Leading Technology in CFX-5 Easy to use
Pre-Processor CFX-Build based on MSC.Patran:
Unstructured hybrid grids
Coupled algebraic multigrid-solver (AMG): Accurate, robust and fast
Solution time scales linear with grid size
Excellent parallel performance
Grid adaptation
UNIX, NT, Linux
7. Leading Technology in CFX-5
Laminar and turbulent flows.
Stationary and transient solutions.
Large variaty of turbulence models.
Transport equations for additional scalars.
Multi-component and multi-phase fluids.
Coupling with solid heat conduction.
Solution depended mesh adaptation.
Linear scaling of solver with grid size.
Scalable parallel performance.
8. Preprocessing with CFX-Build
9. Turbulence Models in CFX-5 Release of the latest turbulence models
k-? Model Variants
k-? Model and BSL Model (Wilcox, Menter)
SST Model (Menter, Blending between k-? and k-?)
Reynolds Stress Models
Extended near-wall treatments
Scalable wall functions for k-?
Automatic near-wall treatment for k-? and SST
LES model (Smagorinski)
Documented validation cases on these models are available
Future: Improved LES and transition modelling
10. Problems of Standard k-? Model Two Problems:
Missing transport effects.
Too large length scales.
Result:
Reduced or omitted separation.
Very often: Too optimistic machine performance.
11. Standard k-? Model (Wilcox)
12. Standard k-? Model (Wilcox) Advantages:
Lower length scales near wall.
Robust sublayer formulation (low-Re).
Problem:
Free stream sensitivity.
Has not replaced k-? models.
13. k-? Model Free Stream Problem
14. k-? vs. k-? Formulation
15. Optimal Two Equation Model Combination of k-w and k-e model:
k-w model near the surface
k-e model for free shear flows (e equation is transformed to w)
Blending is performed automatically based on solution and distance from the surface.
This model is called Baseline Model BSL
Combined with Shear-Stress-Transport limiter offers optimal boundary layer simulation capabilities.
BSL+Limiter gives SST model.
16. Diffuser Flow, 1
17. Diffuser Flow, 2
18. Wall Boundary Treatment
19. Scaling of Variables near Wall
20. Flat Plate: Velocity Profile
21. Flate Plate: Wall Friction
22. Low-Re k-? Model
23. k-? Automatic Switch
24. k-? Automatic Switch
25. Pipe Expansion with Heat Transfer
26. Pipe Expansion with Heat Transfer
27. Pipe Expansion with Heat Transfer
28. Pipe Expansion with Heat Transfer
29. Summary CFX: Advanced CFD software
Fast and robust solver technology
Powerful Pre- and Postprocessing tools
Leading Turbulence Modells
Robust near wall treatment
Allows for
Accurate solutions
Reliable Predictions