•
Depend on the specific purpose and flow conditions of
the problem, different
CFD codes
can be chosen for
different applications (aerospace, marines, combustion,
multi-phase flows, etc.)
•
Once purposes and CFD codes chosen, “
CFD process
” is
the steps to set up the IBVP problem and run the code:
1. Geometry
2. Physics (Setup)
3. Mesh
4. Solve
5. Results

CFD Process
Viscous Model
(ANSYS Fluent-
Setup)
Boundary
Conditions
(ANSYS Fluent-
Setup)
Initial Conditions
(ANSYS Fluent-
Solution)
Convergent Limit
(ANSYS Fluent-
Solution)
Contours, Vectors,
and Streamlines
(ANSYS Fluent-
Results)
Precisions
(ANSYS Fluent-
Solution)
Numerical
Scheme
(ANSYS Fluent-
Solution)
Verification &
Validation
(ANSYS Fluent-
Results)
Geometry
Geometry
Parameters
(ANSYS Design
Modeler)
Physics
Mesh
Solution
Flow properties
(ANSYS Fluent-
Setup)
Unstructured
(ANSYS Mesh)
Steady/
Unsteady
(ANSYS Fluent-
Setup)
Forces Report
(ANSYS Fluent-
Results)
XY Plot
(ANSYS Fluent-
Results)
Domain Shape
and Size
(ANSYS Design
Modeler)
Structured
(ANSYS Mesh)
Iterations/
Steps
(ANSYS Fluent-
Solution)
Results
Green regions indicate ANSYS modules
37

38
Geometry
•
Selection of an appropriate coordinate
•
Determine the domain size and shape
•
Any simplifications needed?
•
What kinds of shapes needed to be used to
best resolve the geometry? (lines, circular,
ovals, etc.)
•
For commercial code, geometry is usually
created using commercial software (either
separated from the commercial code itself, like
Gambit)
•
For research code, commercial software (e.g.
Gridgen) is used.

39
Physics (Setup)
•
Flow conditions and fluid properties
1.
Flow conditions
: inviscid, viscous,
laminar, or
turbulent, etc.
2.
Fluid properties
: density, viscosity,
and
thermal conductivity, etc.
3. Flow conditions and properties usually
presented in dimensional form in
industrial commercial CFD software,
whereas in non-dimensional variables
for research codes.
•
Selection of models:
different models
usually fixed by codes, options for user to
choose
•
Initial and Boundary Conditions:
not
fixed by codes, user needs specify them for

40
Mesh
•
Meshes should be well designed to resolve
important flow features which are dependent
upon flow condition parameters (e.g., Re),
such as the grid refinement inside the wall
boundary layer
•
Mesh can be
generated
by either commercial
codes (Gridgen, Gambit, etc.) or research
code (using algebraic vs. PDE based,
conformal mapping, etc.)
•
The mesh, together with the boundary
conditions need to be exported from
commercial software in a certain format that
can be recognized by the research CFD code
or other commercial CFD software.

41
Solve
•
Setup appropriate numerical parameters
•
Choose appropriate Solvers
•
Solution procedure (e.g. incompressible flows)
Solve the momentum, pressure Poisson
equations and get flow field quantities,
such as velocity, turbulence intensity,
pressure and
integral quantities (lift, drag
forces)

42
Results
•
Reports the saved time history of the
residuals of the velocity, pressure and
temperature, etc.

#### You've reached the end of your free preview.

Want to read all 57 pages?

- Fall '12
- Yang
- Fluid Dynamics, CFD Labs, CFD codes, ANSYS Mesh