文档介绍：Fluent User Services Center Introductory FLUENT Notes
FLUENT Mar 2005
Boundary Conditions
4-1 © Fluent Inc. 9/22/2006
Fluent User Services Center Introductory FLUENT Notes
FLUENT Mar 2005
Defining Boundary Conditions
To define a problem that results in a unique solution, you must specify
information on the dependent (flow) variables at the domain
boundaries
z Specifying fluxes of mass, momentum, energy, etc. into domain.
Defining boundary conditions involves:
z identifying the location of the boundaries (., inlets, walls, symmetry)
z supplying information at the boundaries
The data required at a boundary depends upon the boundary condition
type and the physical models employed.
You must be aware of the information that is required of the boundary
condition and locate the boundaries where the information on the flow
variables are known or can be reasonably approximated
z Poorly defined boundary conditions can have a significant impact on your
solution
4-2 © Fluent Inc. 9/22/2006
Fluent User Services Center Introductory FLUENT Notes
FLUENT Mar 2005
Locating Boundaries: Example
Air
Three possible approaches in
locating inlet boundaries: Combustor Wall
1
z 1. Upstream of manifold
Can use uniform profile 2
3
Properly accounts for mixing
Non-premixed reaction
models
Requires more cells
z 2. Nozzle inlet plane
Non-premixed reaction
models
Nozzle
Requires accurate profile data
1
z 3. Nozzle outlet plane
Manifold
Premixed reaction model
Fuel box
Requires accurate profile
4-3 © Fluent Inc. 9/22/2006
Fluent User Services Center Introductory FLUENT Notes
FLUENT Mar 2005
General Guidelines
Upper pressure boundary modified to ensure that
flow always enters domain.
General guidelines:
z If possible, select boundary
location and shape such that flow
either goes in or out.
Not necessary, but will typical