Fluent网格格式

B. Case and Data File Formats

This Appendix describes the contents and formats of

FLUENT

case and data files.

Descriptions of the sections are grouped according to function.

?

Section

B.2

: The differences between formatted and binary files.

?

Section

B.3

: Creating grids for

FLUENT

.

?

Section

B.4

: The boundary conditions, material properties, and solver control settings.

?

Section

B.3

and Section

B.5

: Importing solutions into another postprocessor.

The case and data files may contain other sections that are intended for internal use only.

B.1 Guidelines

The

FLUENT

case and data files are broken into several sections according to the following guidelines:

?

Each section is enclosed in parentheses and begins with a decimal integer indicating its type. This

integer is different for formatted and binary files (Section

B.2

).

?

All groups of items are enclosed in parentheses. This makes skipping to ends of (sub)sections and

parsing

them

very

easy.

It

also

allows

for

easy

and

compatible

addition

of

new

items

in

future

releases.

?

Header information for lists of items is enclosed in separate sets of parentheses preceding the items,

and the items are enclosed in their own parentheses.

B.2 Formatting Conventions in Binary and Formatted Files

For formatted files, examples of file sections are given in Sections

B.3

and

B.4

. For binary files, the header

indices described in this section (e.g., 10 for the node section) are preceded by 20 for single-precision binary

data, or by 30 for double-precision binary data (e.g., 2010 or 3010 instead of 10). The end of the binary data

is indicated by End of Binary Section 2010 or End of Binary Section 3010 before the closing parameters of

the section.

An example with the binary data represented by periods is as follows:

(2010 (2 1 2aad 2 3)(

.

.

.

)

End of Binary Section 2010)

B.3 Grid Sections

Grid sections are stored in the case file. A grid file is a subset of a case file, containing only those sections

pertaining to the grid. The currently defined grid sections are:

?

Comment (See

B.3.1

)

?

Header (See

B.3.2

)

?

Dimensions (See

B.3.3

)

?

Nodes (See

B.3.4

)

?

Periodic Shadow Faces (See

B.3.5

)

?

Cells (See

B.3.6

)

?

Faces (See

B.3.7

)

?

Face Tree (See

B.3.8

)

?

Cell Tree (See

B.3.9

)

?

Interface Face Parents (See

B.3.10

)

The section ID numbers are indicated in both symbolic and numeric forms. The symbolic representations are

available as symbols in a

Scheme

source file ( ), which is available from Fluent Inc., or as macros

in a C header file ( xfile.h), which is located in the following directory in your installation area:

1

//fluent6.x/client/src/xfile.h

B.3.1 Comment

Index:

0

Scheme symbol:

xf-comment

C macro:

XF_COMMENT

Status:

optional

Comment sections can appear anywhere in the file (except within other sections) as:

(0

It

is

recommended

to

precede

each

long

section,

or

group

of

related

sections,

by

a

comment

section

explaining what is to follow.

Example:

(0

(37 (

(relax-mass- flow 1)

(default-coefficient ())

(default-method 0)

))

B.3.2 Header

Index:

1

Scheme symbol:

xf-header

C macro:

XF_HEADER

Status:

optional

Header sections can appear anywhere in the file (except within other sections) as:

(1

The purpose of this section is to identify the program that wrote the file. Although it can appear anywhere, it

is one of the first sections in the file. Additional header sections indicate other programs that may have been

used in generating the file. It provides a history mechanism showing

where the file came from and how it

was processed.

B.3.3 Dimensions

Index:

2

Scheme symbol:

xf-dimension

C macro:

XF_DIMENSION

Status:

optional

The dimensions of the grid appear as:

(2 ND)

where ND is 2 or 3. This section is supported as a check that the grid has the appropriate dimension.

B.3.4 Nodes

Index:

10

Scheme symbol:

xf-node

C macro:

XF_NODE

Status:

required

Example:

(10 (zone-id first-index last-index type ND)(

x1 y1 z1

x2 y2 z2

2

.

.

.

))

?

If zone-id is zero, this provides the total number of nodes in the grid. first-index will then be one,

last-index

will

be

the

total

number

of

nodes

in

hexadecimal

,

type

is

equal

to

1,

ND

is

the

dimensionality

of

the

grid,

and

there

are

no

coordinates

following.

The

parentheses

for

the

coordinates are not there either.

For example: (10 (0 1 2d5 1 2))

?

If

zone-id

is

greater

than

zero,

it

indicates

the

zone

to

which

the

nodes

belong.

first-index

and

last-index are the indices of the nodes in the zone,

in hexadecimal

. The values of last-index in each

zone must be less than or equal to the value in the declaration section.

Type

is always equal to 1.

ND is an optional argument that indicates the dimensionality of the node data, where ND is 2 or 3.

If

the

number

of

dimensions

in

the

grid

is

two,

as

specified

by

the

node

header,

then

only

and

coordinates are present on each line.

Example of two-dimensional grid:

(10 (1 1 2d5 1 2)(

1.500000e-01 2.500000e-02

1.625000e-01 1.250000e-02

3

.

.

.

1.750000e-01 0.000000e+00

2.000000e-01 2.500000e-02

1.875000e-01 1.250000e-02

))

Because

the

grid

connectivity

is

composed

of

integers

representing

pointers

(see

Cells

and

Faces),

using

hexadecimal conserves space in the file and provides for faster file input and output. The header indices are

in hexadecimal so that they match the indices in the bodies of the grid connectivity sections. The zone-id and

type are also in hexadecimal for consistency.

B.3.5 Periodic Shadow Faces

Index:

18

Scheme symbol:

xf-periodic-face

C macro:

XF_PERIODIC_FACE

Status:

required only for grids with periodic boundaries

This

section

indicates

the

pairings

of

periodic

faces

on

periodic

boundaries.

Grids

without

periodic

boundaries do not have sections of this type. The format of the section is as follows:

(18 (first-index last-index periodic-zone shadow-zone)(

f00 f01

f10 f21

f20 f21

.

.

.

))

where

first- index

=

index of the first periodic face pair in the list

last- index

=

index of the last periodic face pair in the list

periodic-zone

=

zone ID of the periodic face zone

shadow-zone

=

zone ID of the corresponding shadow face zone

These

are

in

hexadecimal

format.

The

indices

in

the

section

body

(

f*)

refer

to

the

faces

on

each

of

the

periodic boundaries (in hexadecimal), the indices being offsets into the list of faces for the grid.

Note:

In this case, first-index and last- index do not refer to face indices. They refer to indices in the list of periodic

pairs.

Example:

(18 (1 2b a c) (

12 1f

13 21

ad 1c2

.

.

.

))

B.3.6 Cells

4

Index:

12

Scheme symbol:

xf-cell

C macro:

XF_CELL

Status:

required

The declaration section for cells is similar to that for nodes.

(12 (zone-id first-index last-index type element- type))

Again, zone-id is zero to indicate that it is a declaration of the total number of cells. If last-index is zero, then

there are no cells in the grid. This is useful when the file contains only a surface mesh to alert

FLUENT

that

it

cannot

be

used.

In

a

declaration

section,

the

type

is

ignored,

and

has

the

value

of

zero,

while

the

element-type is ignored completely.

For example,

(12 (0 1 3e3 0))

It states that there are 3e3 (hexadecimal) = 995 cells in the grid. This declaration section is required and must

precede the regular cell sections. The element-type in a regular cell section header indicates the type of cells

in the section, as follows:

element-type

description

nodes/cell

faces/cell

0

mixed

1

triangular

3

3

2

tetrahedral

4

4

3

quadrilateral

4

4

4

hexahedral

8

6

5

pyramid

5

5

6

wedge

6

5

Regular

cell

sections

have

no

body,

but

they

have

a

header

of

the

same

format

where

first-index

and

last-index indicate the range for the particular zone, type indicates whether the cell zone is an active zone

(solid or fluid), or inactive zone (currently only parent cells resulting from hanging node adaption). Active

zones are represented with type=1, while inactive zones are represented with type=32.

In the earlier versions of

FLUENT

, a distinction was made used between solid and fluid zones. This is now

determined by properties (i.e., material type).

A

type

of

zero

indicates

a

dead

zone

and

will

be

skipped

by

FLUENT

.

If

a

zone

is

of

mixed

type

( element-type=0), it will have a body that lists the element type of each cell.

Example

:

(12 (9 1 3d 0 0)(

1 1 1 3 3 1 1 3 1

.

.

.

))

Here, there are 3d (hexadecimal) = 61 cells in cell zone 9, of which the first 3 are triangles, the next 2 are

quadrilaterals, and so on.

B.3.7 Faces

Index:

13

Scheme symbol:

xf-face

C macro:

XF_FACE

Status:

required

The face section has a header with the same format as that for cells (but with a section index of 13).

5

(13 (zone-id first-index last-index type element-type))

A zone- id of zero indicates a declaration section with no body, and element-type indicates the type of faces in

that zone. The body of a regular face section contains the grid connectivity, and each line appears as follows:

n0 n1 n2 cr cl

where,

n*

=

defining nodes (vertices) of the face

c*

=

adjacent cells

This is an example of the triangular face format. The actual number of nodes depends on the element type.

The order of the cell indices is important. The first cell ( cr) is the cell on the right side of the face and cl is

the cell on the left side.

Handedness is determined by the right- hand rule. If you curl the fingers of your right hand in the order of the

nodes, your thumb will point to the right side of the face.

?

vector pointing outside the grid plane is used to determine the right-hand-side cell ( cr)

In 2D grids, the

k

?

?

r

?

< br>. If there is no adjacent cell, then either cr or cl is zero. All cells, faces, and nodes have positive

from

k

indices. For files containing only a boundary mesh, both these values are zero. If it is a two-dimensional grid,

n2 is omitted.

If the face zone is of mixed type ( element-type = 0), the body of the section will include the face type and

will appear as follows:

type v0 v1 v2 c0 c1

Here, type is the type of face, as defined in the following table:

element- type

face type

nodes/face

0

mixed

2

linear

2

3

triangular

3

4

quadrilateral

4

The current valid boundary condition types are defined in the following table:

bc name

bc id

interior

2

wall

3

pressure- inlet, inlet-vent, intake-fan

4

pressure-outlet, exhaust-fan, outlet- vent

5

symmetry

7

periodic-shadow

8

pressure-far-field

9

velocity-inlet

10

periodic

12

fan, porous-jump, radiator

14

mass-flow-inlet

20

interface

24

parent (hanging node)

31

outflow

36

axis

37

For non-conformal grid interfaces, the faces resulting from the intersection of the non-conformal grids are

6

placed in a separate face zone. A factor of 1000 is added to the type of these sections, e.g., 1003 is a wall

zone.

For information on face-node connectivity for various cell types in

FLUENT

, refer to Section

6.1.2

.

B.3.8 Face Tree

Index:

59

Scheme symbol:

xf-face-tree

C macro:

XF_FACE_TREE

Status:

only for grids with hanging-node adaption

This section indicates the face hierarchy of the grid containing hanging nodes. The format of the section is as

follows:

(59 (face-id0 face-id1 parent-zone-id child-zone-id)

(

number-of-kids kid-id-0 kid-id-1 ... kid-id-n

.

.

.

))

where,

face-id0

=

index of the first parent face in the section

face-id1

=

index of the last parent face in the section

parent-zone-id

=

ID of the zone containing parent faces

child-zone-id

=

ID of the zone containing children faces

number-of-kids

=

the number of children of the parent face

kid-id-n

=

the face IDs of the children

These are in hexadecimal format.

B.3.9 Cell Tree

Index:

58

Scheme symbol:

xf-cell-tree

C macro:

XF_CELL_TREE

Status:

only for grids with hanging-node adaption

This section indicates the cell hierarchy of the grid containing hanging nodes. The format of the section is as

follows:

(58 (cell-id0 cell-id1 parent-zone-id child-zone-id)

(

number-of-kids kid-id-0 kid-id-1 ... kid-id-n

.

.

.

))

where,

cell-id0

=

index of the first parent cell in the section

cell-id1

=

index of the last parent cell in the section

parent-zone-id

=

ID of the zone containing parent cells

child-zone-id

=

ID of the zone containing children cells

7

number- of-kids

=

the number of children of the parent cell

kid-id-n

=

the cell IDs of the children

These are in hexadecimal format.

B.3.10 Interface Face Parents

Index:

61

Scheme symbol:

xf-face-parents

C macro:

XF_FACE_PARENTS

Status:

only for grids with non-conformal interfaces

This

section

indicates

the

relationship

between

the

intersection

faces

and

original

faces.

The

intersection

faces (children) are produced from intersecting two non-conformal surfaces (parents) and are some fraction

of the original face. Each child will refer to at least one parent. The format of the section is as follows:

(61 (face-id0 face-id1)

(

parent-id-0 parent-id-1

.

.

.

))

where,

face- id0

=

index of the first child face in the section

face-id1

=

index of the last child face in the section

parent-zone-id

=

index of right-side parent face

child-zone-id

=

index of left-side parent face

number-of-kids

=

the number of children of the parent face

These are in hexadecimal format.

If

you read a non-conformal grid from

FLUENT

into

TGrid

,

TGrid

will skip this

section, so it will not

maintain all the information necessary to preserve the non-conformal interface. When you read the grid back

into

FLUENT

, you will need to recreate the interface.

Example Files

Example 1

Figure

B.3.1

illustrates a simple quadrilateral mesh with no periodic boundaries or hanging nodes.

Figure B.3.1:

Quadrilateral Mesh

8

The following describes this mesh:

(0

(0

(2 2)

(12 (0 1 3 0))

(13 (0 1 a 0))

(10 (0 1 8 0 2))

(12 (7 1 3 1 3))

(13 (2 1 2 2 2)(

1 2 1 2

3 4 2 3))

(13 (3 3 5 3 2)(

5 1 1 0

1 3 2 0

3 6 3 0))

(13 (4 6 8 3 2)(

7 4 3 0

4 2 2 0

2 8 1 0))

(13 (5 9 9 a 2)(

8 5 1 0))

(13 (6 a a 24 2)(

6 7 3 0))

(10 (1 1 8 1 2)

(

1.00000000e+00

0.00000000e+00

1.00000000e+00

1.00000000e+00

2.00000000e+00

0.00000000e+00

2.00000000e+00

1.00000000e+00

0.00000000e+00

0.00000000e+00

3.00000000e+00

0.00000000e+00

3.00000000e+00

1.00000000e+00

0.00000000e+00

1.00000000e+00))

Example 2

Figure

B.3.2

illustrates a simple quadrilateral mesh with periodic boundaries but no hanging nodes. In this

example, bf9 and bf10 are faces on the periodic zones.

9