CFX-4
Introductory Training (Dec 1999)
4 -1
CFX-4.3 V4.3.1H
Lecture 4
Geometry Creation in
CFX-Build
CFX-Build
CFX-4
Introductory Training (Dec 1999)
4 -2
CFX-4.3 V4.3.1H
Tolerance 公差
? The initial tolerance is important for geometry
construction and grid construction.
? The preferred method to set the tolerance is to
work from the Preferences pull down menu and
select Global...
CFX-4
Introductory Training (Dec 1999)
4 -3
CFX-4.3 V4.3.1H
Tolerance
? Set the Global Model Tolerance to one-tenth of
the expected minimum cell size.
CFX-4
Introductory Training (Dec 1999)
4 -4
CFX-4.3 V4.3.1H
Tolerance Example
Desire 10 uniform
cells across length.
1 unit length
Tolerance should
be set to 0.01.
CFX-4
Introductory Training (Dec 1999)
4 -5
CFX-4.3 V4.3.1H
Units
? It is possible to work in any unit system for
geometry creation (ft,in,mm,cm,m).
? We suggest scaling the geometry to metric
units on the Analysis form for geo file creation.
CFX-4
Introductory Training (Dec 1999)
4 -6
CFX-4.3 V4.3.1H
Units
? However,appropriate units should be used to
build the geometry,(Hint,try to keep the
dimensions,di,of the geometry in the range
0.01<di<100.) This will reduce the possibility of
floating point errors.
? Any consistent system of units can be used.
CFX-4
Introductory Training (Dec 1999)
4 -7
CFX-4.3 V4.3.1H
Steps in Geometry Creation
- build wire frame using points,curves,surfaces,
and solids.
- define constraints for solids with area mismatch.
- define boundary conditions (inlet,outlet,walls).
- mesh all surfaces.
-generate internal volume mesh and geo file.
Geometry
Constraints
Patches
Mesh
Analysis
CFX-4
Introductory Training (Dec 1999)
4 -8
CFX-4.3 V4.3.1H
Geometry Building
? points (cyan青蓝色 ).
? curves (yellow)
vector function of a parametric variable
points created implicitly when constructing curves,
surfaces,and solids
not necessary to construct explicit points and then
higher order entities
note differences between explicit curves and
implicit edges.
CFX-4
Introductory Training (Dec 1999)
4 -9
CFX-4.3 V4.3.1H
Geometry Building
? simple surfaces (green) are composed of 4
edges and 4 vertices
> construct solids using simple surfaces only
> simple surfaces are meshed using the isomesher.
CFX-4
Introductory Training (Dec 1999)
4 -10
CFX-4.3 V4.3.1H
Geometry Building
? solids (blue)
characterized by a bounding set of surfaces
6 surfaces,8 vertices
parametric function of 3 variables (I,J,K)
meshed with the isomesher
non-parametric solids (B-rep) cannot be used to
create a structured grid.
CFX-4
Introductory Training (Dec 1999)
4 -11
CFX-4.3 V4.3.1H
Methodology
ACTION OBJECT METHOD
Create
Edit
Delete
Transform
Point
Curve
Surface
Solid
Coordinate
坐标
XYZ
Revolve
Scale
Extrude
Glide
.
.
.
CFX-4
Introductory Training (Dec 1999)
4 -12
CFX-4.3 V4.3.1H
Geometry Form Actions
? the Action selected determines the choice of
Objects,
? the Object selected determines the choice
of Methods.
CFX-4
Introductory Training (Dec 1999)
4 -13
CFX-4.3 V4.3.1H
Action Commands
? create
creates an object.
? edit
modifies original object.
? show
provides information about object.
? transform
creates new objects by modifying the original.
? delete
removes object from viewport.
CFX-4
Introductory Training (Dec 1999)
4 -14
CFX-4.3 V4.3.1H
Create/Point/XYZ
? create a point
using cartesian,
cylindrical,or
spherical
coordinates.
CFX-4
Introductory Training (Dec 1999)
4 -15
CFX-4.3 V4.3.1H
Create/Curve/Point
? creates a curve
based on 2,3,
or 4 points.
CFX-4
Introductory Training (Dec 1999)
4 -16
CFX-4.3 V4.3.1H
Create/Curve/Project
? new curves are
projected to a
surface.
? projection direction
specified as:
normal to plane
normal to surface
along a vector
along a viewfactor
of the viewport.
CFX-4
Introductory Training (Dec 1999)
4 -17
CFX-4.3 V4.3.1H
Create/Curve/Intersect
? new curves created
by intersecting a
surface with
another surface (2-
surface option)
flat plane defined
normal to the surface
(plane-surface
option).
CFX-4
Introductory Training (Dec 1999)
4 -18
CFX-4.3 V4.3.1H
Create/Surface/Curve
? creates surfaces
between a list of
2 or more
curves.
CFX-4
Introductory Training (Dec 1999)
4 -19
CFX-4.3 V4.3.1H
Create/Surface/Edge
? creates a new
surface by using 4
edges.
CFX-4
Introductory Training (Dec 1999)
4 -20
CFX-4.3 V4.3.1H
Create/Solid/Surface
? create a solid
between a list of
2 or more
surfaces.
CFX-4
Introductory Training (Dec 1999)
4 -21
CFX-4.3 V4.3.1H
Create/Solid/Face
? create a solid
based on 6 exterior
faces.
? boundary faces
must be simple
surfaces (green).
CFX-4
Introductory Training (Dec 1999)
4 -22
CFX-4.3 V4.3.1H
Transform/Point/Translate
? creates points by
specifying an off-
set.
CFX-4
Introductory Training (Dec 1999)
4 -23
CFX-4.3 V4.3.1H
Transform/Curve/Translate
? creates a new
curve by specifying
translation vector.
CFX-4
Introductory Training (Dec 1999)
4 -24
CFX-4.3 V4.3.1H
Transform/Surface/Scale
CFX-4
Introductory Training (Dec 1999)
4 -25
CFX-4.3 V4.3.1H
Edit/Curve/Merge
? combines existing
curves to form one or
more new curves.
CFX-4
Introductory Training (Dec 1999)
4 -26
CFX-4.3 V4.3.1H
Edit/Curve/Break
? creates two curves
by breaking an
original curve with a
point,or at a
parametric position.
? parametric
directions may be
viewed using
Display/Geometry/S
how_Parametric_Di
rection.
CFX-4
Introductory Training (Dec 1999)
4 -27
CFX-4.3 V4.3.1H
Coordinate Frame
? cartesian,cylindrical,and spherical
Create Delete Show TransformAction
Object
Method
Coord Coord Coord Coord
Attributes Translate
Rotate
3 point
Axis
Euler
Normal
CFX-4
Introductory Training (Dec 1999)
4 -28
CFX-4.3 V4.3.1H
Show Command
Point Curve Solid Coord Plane Vector Surface
Locat,
Dist.
Node
Node
Lth.Rg
Angle
Arc
Attrib,Attrib,
Node
Normal
Ar,Rng.
Attrib,
ShowAction
Object
Method
CFX-4
Introductory Training (Dec 1999)
4 -29
CFX-4.3 V4.3.1H
Deleting Geometry
Delete
Solid Curve Point Any Surf,Coord
Action
Object