© Fluent Inc. 4/20/2005 2-1 Introductory FLUENT Notes FLUENT v6.1 Feb 2003 Fluent User Services Center www.fluentusers.com Solution process Solution process ( ) 0 = ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ ⋅ ∇ + ∂ ∂ ∫∫∫ V t u ρ ρ Geometry Geometry CAD, Gambit CAD, Gambit Physics Fluent Physics Fluent Mesh generation Mesh generation Gambit Gambit Visualization Visualization Fluent Fluent Mathematics Mathematics Fluent Fluent • Convection • Conduction • Turbulence • Transient flow • Combustion • Radiation • Rotation • Multiphase • Chemical reactions • Phase change • Acoustics • Deforming mesh • EMC • Plasma flows • ...
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© Fluent Inc. 4/20/20052-1
Introductory FLUENT NotesFLUENT v6.1 Feb 2003
Fluent User Services Center
www.fluentusers.com
Solution processSolution process
( ) 0=⎟⎠⎞
⎜⎝⎛ ⋅∇+∂∂
∫∫∫V t
uρρGeometryGeometry
CAD, GambitCAD, Gambit
PhysicsFluent
PhysicsFluent
Mesh generationMesh generationGambitGambit
VisualizationVisualizationFluentFluent
MathematicsMathematicsFluentFluent
• Convection• Conduction• Turbulence• Transient flow• Combustion• Radiation• Rotation• Multiphase• Chemical
reactions• Phase change• Acoustics• Deforming
mesh• EMC• Plasma flows• ...
© Fluent Inc. 4/20/20052-2
Introductory FLUENT NotesFLUENT v6.1 Feb 2003
Fluent User Services Center
www.fluentusers.com
CFD Analysis: Basic Steps
Problem Identification and Pre-Processing1. Define your modeling goals.2. Identify the domain you will model.3. Design and create the grid.Solver Execution4. Set up the numerical model.5. Compute and monitor the solution.Post-Processing6. Examine the results.7. Consider revisions to the model.
© Fluent Inc. 4/20/20052-3
Introductory FLUENT NotesFLUENT v6.1 Feb 2003
Fluent User Services Center
www.fluentusers.com
Tools for Post-ProcessingMany post-processing tools are available.Post-Processing functions typically operate on surfaces.
Surfaces are automatically created from zones.Additional surfaces can be created by user.
Example: an Iso-Surface of a constant grid coordinate can be created for viewing data within a plane.
© Fluent Inc. 4/20/20052-4
Introductory FLUENT NotesFLUENT v6.1 Feb 2003
Fluent User Services Center
www.fluentusers.com
Tools for Post-Processing: Graphics (1)Display/Grid...
© Fluent Inc. 4/20/20052-5
Introductory FLUENT NotesFLUENT v6.1 Feb 2003
Fluent User Services Center
www.fluentusers.com
Tools for Post-Processing: Graphics (2)Display/Contours...
© Fluent Inc. 4/20/20052-6
Introductory FLUENT NotesFLUENT v6.1 Feb 2003
Fluent User Services Center
www.fluentusers.com
Post-Processing: Node vs Cell ValuesFluent calculates field variable data at cell centers.Node values of the grid are either:
calculated as the average of neighboring cell data, or,defined explicitly (when available) with boundary condition data.
Node values on surfaces are interpolated from grid node data.Data files store:
data at cell centersnode value data for primitive variables at boundary nodes.
Enable Node Values to interpolate field data to nodes.
© Fluent Inc. 4/20/20052-7
Introductory FLUENT NotesFLUENT v6.1 Feb 2003
Fluent User Services Center
www.fluentusers.com
Tools for Post-Processing: Graphics (3)Display/Vectors...
© Fluent Inc. 4/20/20052-8
Introductory FLUENT NotesFLUENT v6.1 Feb 2003
Fluent User Services Center
www.fluentusers.com
Tools for Post-Processing: Graphics (4)Display/Pathlines...
© Fluent Inc. 4/20/20052-9
Introductory FLUENT NotesFLUENT v6.1 Feb 2003
Fluent User Services Center
www.fluentusers.com
Tools for Post-Processing: Graphics (5)Plot/XY Plot...
© Fluent Inc. 4/20/20052-10
Introductory FLUENT NotesFLUENT v6.1 Feb 2003
Fluent User Services Center
www.fluentusers.com
Tools for Post-Processing: Graphics (6)Plot/Residuals...
© Fluent Inc. 4/20/20052-11
Introductory FLUENT NotesFLUENT v6.1 Feb 2003
Fluent User Services Center
www.fluentusers.com
Tools for post-processing: Reports (1)Report/Flux Reports…
Net flux is calculated.Total Heat Transfer Rate includes radiation.
© Fluent Inc. 4/20/20052-12
Introductory FLUENT NotesFLUENT v6.1 Feb 2003
Fluent User Services Center
www.fluentusers.com
Tools for post-processing: Reports (2)Report/Surface Integrals…
slightly less accurate on user-generated surfaces due to interpolation error.
© Fluent Inc. 4/20/20052-13
Introductory FLUENT NotesFLUENT v6.1 Feb 2003
Fluent User Services Center
www.fluentusers.com
Tools for post-processing: Reports (3)Report/Volume Integrals…
© Fluent Inc. 4/20/20052-14
Introductory FLUENT NotesFLUENT v6.1 Feb 2003
Fluent User Services Center
www.fluentusers.com
When can we trust in our Solution?When it is convereged!
All discrete conservation equations (momentum, energy, etc.) are obeyed in all cells to a specified tolerance (Residuals).
Overall mass, momentum, energy, and scalar balances are achieved.(Reports)
Solution no longer changes with more iterations.(Monitors)
All equations converged.
10-3
10-6
© Fluent Inc. 4/20/20052-15
Introductory FLUENT NotesFLUENT v6.1 Feb 2003
Fluent User Services Center
www.fluentusers.com
When can we trust in our Solution?
AND...
© Fluent Inc. 4/20/20052-16
Introductory FLUENT NotesFLUENT v6.1 Feb 2003
Fluent User Services Center
www.fluentusers.com
When can we trust in our Solution?
When it is accurate!Use the second-order upwind discretization scheme for final results.Solve/Controls/Solution…
Ensure that solution is grid-independent:
Use adaption to modify the grid or create additional meshes for the grid-independence study.Adapt/Region…Adapt/Gradient…Adapt/Iso-Value
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