CFX用户手册-User Fortran

User Fortran

Introduction

The chapter discusses:

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User CEL Functions and Routines

User Junction Box Routines

Shared Libraries

User Parameters

Utility Routines for User Functions

ANSYS CFX Memory Management System (MMS)

User CEL Examples

User Junction Box Examples

Using CFX-4 Routines in ANSYS CFX

To

allow

you

to

add

additional

features

and

physical

models

to

ANSYS

CFX,

you

can

write

your

own

subroutines

in

Fortran

and

have

the

ANSYS

CFX- Solver

call these routines through a source code interface. You may also wish

to implement customized physical models which would never be available

in ANSYS CFX due to confidentiality considerations.

ANSYS

CFX

supports

user

subroutines

written

in

Fortran

77

or

Fortran

90.

A list of supported compilers for each platform is available. Using

Fortran

77 whenever possible is recommended.

Two different kinds of user routines are available in ANSYS CFX:

CFX

< br>可以利用两种不同的方式应用用户子程序

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User defined CEL (CFX Expression Language) functions can be used

within a CEL expression, following the standard CEL rules.

For

details, see User CEL Functions and Routines.

用户定义

CEL

（

User defined CEL

）函数可以在

CEL

表达式中使 用

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Junction box routines can be used at several places in the ANSYS

CFX-Solver

to

execute

user

code.

For

details,

see

User

Junction

Box

Routines.

Junction box routines

可以在

ANSYS CFX- Solver

中执行用户代码

The following tasks can be accomplished with user subroutines in ANSYS

CFX:

通过 用户程序可以在

CFX

中完成以下内容：

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Input of user data (e.g., data required for profile boundary

conditions or externally generated sources).

User- specified boundary conditions (e.g., profile boundary

conditions).

User- specified

initial

conditions

(e.g.,

externally

generated

flow

fields,

random

distribution

or

disturbance

of

existing

solutions).

User-specified source terms (e.g., externally generated body

forces or general additional source terms used to implement new

physical models).

Junction

box

routines

called

every

timestep

which

acts

as

a

general

interface between the ANSYS CFX-Solver and other software (e.g.,

structure mechanic codes). Junction boxes also offer an interface

for advanced monitoring and solution output.

User

particle

routines

are

used

to

specify

sources

of

momentum,

heat

and

mass

transfer,

and

can

also

be

used

to

specify

injection

regions

for

particles.

The

structure

of

particle

user

routines

is

the

same.

An example of this functionality is available.

For details, see Structure of User CEL Functions.

For details, see Particle User Sources.

For details, see User Defined.

Note that ANSYS CFX includes features such as advanced monitoring of

solution

variables

or

global

values

and

extended

CEL

functionality,

which

may reduce your need for user subroutines.

To

use

junction

box

routines,

you

will

need

to

be

familiar

with

the

ANSYS

CFX MMS (Memory Management System) to set up and pass around user data

for

access

in

any

subroutine.

For

details,

see

ANSYS

CFX

Memory

Management

System (MMS).

Shared libraries allow subroutines to be re-used without recompilation

for

successive

ANSYS

CFX-Solver

runs

or

even

for

different

applications.

The location of a shared library is specified in ANSYS CFX-Pre. During

execution of the ANSYS CFX- Solver, the user subroutines are loaded from

the specified shared libraries.

For details, see Shared Libraries.

User CEL Functions and Routines

User CEL functions allow

you to create

your own

functions in addition to

the predefined CEL functions (e.g., sin, cos, step, etc.). You can then

use these functions in any expression where a CEL function can be used.

A

user

CEL

function

passes

an

argument

list

to

a

subroutine

that

you

have

written, and then uses the returned values from the subroutine to set

values for the quantity of interest. The figure below demonstrates the

concept.

All

variables

that

are

available

for

use

in

standard

CEL

expressions

are

also

available

for

use

in

User

CEL

Expressions.

A

list

of

these

variables

is available.

For details, see Variables Available for use in CEL

Expressions.

Details on creating user CEL functions in ANSYS CFX-Pre and defining

quantities via an expression with an argument list are available.

For details, see User Routine Details View.

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For details, see

User Functions

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Details on creating shared libraries and compiling subroutines are

available.

For details, see Shared Libraries.

Examples

of

using

user

CEL

functions

are

available.

For

details,

see

User

CEL Examples.

Structure of User CEL Functions

A User Fortran file

may contain

several

user routines

that can be called

from the ANSYS CFX-Solver, as well as any secondary routines that are

called only from other routines in this file.

In addition to any comments and declarations that you may wish to add,

the basic structure of a user CEL function is:

#include

dllexport()

SUBROUTINE (

& NLOC, NRET, NARG, RET, ARGS, CRESLT, CZ,DZ,IZ,LZ,RZ )

C

INTEGER NLOC,NARG,NRET

CHARACTER CRESLT*(*)

REAL ARGS(NLOC,NARG), RET(NLOC,NRET)

C

INTEGER IZ(*)

CHARACTER CZ(*)*(1)

DOUBLE PRECISION DZ(*)

LOGICAL LZ(*)

REAL RZ(*)

C

.... executable statements

END

The dllexport() macro is used to ensure that a calling name is known

externally on those platforms that require it for successful runtime

linking.

The

macro

is

defined

in

an

include

file

so

#include

should be the first line of the Fortran file.

One dllexport() should be specified for every routine that the ANSYS

CFX-Solver can call in the Fortran file.

Each

dllexport()

must

precede

the

SUBROUTINE

statement

that

it

refers

to

and must start in column 1. The argument of the dllexport macro should

be

the

name

of

the

subroutine

in

lower

case

and

should

not

contain

spaces.

User

CEL

functions

have

a

fixed

argument

list

which

contains

the

following

data fields:

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NLOC:

Number

of

locations

in

space

over

which

the

calculations

have

to be performed.

NARG: Number of arguments passed to the function.

ARGS(1:NLOC,1:NARG): Arguments passed to the function (at each

point in space).

NRET: Number of return variables. This is always 1 in ANSYS CFX,

but is included to allow future extensions.

RET(1:NLOC,1:NRET): Return variables (at each point in space).

CZ(*), DZ(*), IZ(*), LZ(*), RZ(*): CHARACTER, DOUBLE PRECISION,

INTEGER, LOGICAL and REAL stacks.

The length (NLOC) of the arguments (ARGS) and the return value (RET) of

user CEL functions is determined by the locale for which the routine is

called. For example, for a boundary

element group, NLOC is the number of

faces in the group, and for vertices, NLOC is the number of vertices in

the current zone.

Note

that,

in

general,

your

user

CEL

function

will

be

called

several

times

during each iteration and the value of NLOC will be different for each

call.

This

is

because

the

ANSYS

CFX- Solver

will

split

the

specified

region

(e.g., a boundary condition region) into a number of smaller ‘pieces'

and

call

your

function

for

each

piece.

Your

user

subroutine

should

be

coded

to deal with this.

The stacks are required if the information specified on the right side

of the CEL expression (e.g., B*C and D in A

=

UR(B*C,

D)) is not

sufficient to calculate A. It might be necessary to pick up additional

data

(e.g.,

user

input

data,

data

at

other

locales,

gradients, etc).

For

details, see Utility Routines for User Functions.

This data is accessed

from

the

ANSYS

CFX

Memory

Management

System

and

requires

the

global

stacks.

Therefore,

the

global

stacks

are

added

to

the

argument

list.

For

details,

see ANSYS CFX Memory Management System (MMS).

A template user CEL function Fortran file named ucf_template.F can be

found in /examples/.

Note that all strings used in User Fortran are case sensitive.

User CEL Function Units

On

entry

into

a

user

CEL

function

routine,

the

arguments

are

automatically

converted into the units

specified

in the

Argument List

list in the

User

Function

Editor

(labelled

Argument

List

in

the

definition

for

the

function

in the CCL file LIBRARY section).

On exit, the results are automatically converted from the

Result Units

into the solution units used by the ANSYS CFX-Solver.

This ability to choose the working units for the routine with automatic

conversion may be useful for creating interfaces between the ANSYS

CFX-Solver and third-party data or applications.

User CEL Example 1: User Defined Momentum Source

Problem Setup

A common application of user CEL functions is the specification of user

defined source terms. In the following example, a constant source term

for the y-component of the momentum equation has to be applied on two

rectangular boxes characterized by their extension in the x and y

coordinate direction.

Creating the User CEL Function

Additional information on creating user CEL functions in ANSYS CFX-Pre

is available.

For details, see

User Functions

.

First,

you

should

first

create

a

user

routine

with

the

following

settings:

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Routine Name: UserSourceRoutine

Option: User CEL Function

Calling Name: user_source

Library Name: MomentumSource1

Library Path: /home/cfxuser/shared_libraries

Next, you should create a User Function with the following settings:

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Function Name: UserSource

Option: User Function

User Routine Name:

Argument List: [m], [m]

Result Units: [kg m^-2 s^-2]

In this example, the compiled code for the user subroutine

MomentumSource1.F

is

stored

in

the

shared

library

(the prefix and suffix may vary depending on your platform), which can

be found under the /home/cfxuser/shared_libraries/

directory. If there is

a problem linking

the shared library

to the ANSYS

CFX-Solver, you

can

check that

it

has been

created, but you will usually

not need to know about this library.

The new user CEL function can now be used to set the momentum source

components within the subdomain as follows:

Momentum x-comp: 0.0

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Momentum y-comp: UserSource(X,Y)

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Momentum z-comp: 0.0

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These values are set on the Subdomain Sources form.

For details, see

Sources Tab.

User Fortran Routine

Source

terms

for

the

momentum

equations

can

be

specified

in

CEL

for

a

given

subdomain. Since the user CEL routine defined the extent of the source,

the source subdomain can be defined

to cover

the entire flow

domain. The

subroutine was developed from the template routine ucf_template.F

available in /examples/. Note that some commented sections of

the routine have not been included here. The routine MomentumSource1.F

has the following form:

#include

dllexport(user_source)

SUBROUTINE USER_SOURCE (

&

NLOC,NRET,NARG ,RET,ARGS,CRESLT,CZ,DZ,IZ,LZ,RZ)

C

C .....

C

C ------------------------------

C Argument list

C ------------------------------

C

INTEGER NLOC, NRET, NARG

CHARACTER CRESLT*(*)

REAL RET(1:NLOC,1:NRET), ARGS(1:NLOC,1:NARG)

C

INTEGER IZ(*)

CHARACTER CZ(*)*(1)

DOUBLE PRECISION DZ(*)

LOGICAL LZ(*)

REAL RZ(*)

C

C .....

C

C ------------------------------

C Executable statements

C ------------------------------

C

C-------------------------------------------- -------------

C SOURCE = RET(1:NLOC,1)

C X = ARGS(1:NLOC,1)

C Y = ARGS(1:NLOC,2)

C----------------------- ----------------------------------

C

C---- Low level user routine

CALL USER_SOURCE_SUB (NLOC,RET(1,1),ARGS(1,1),ARGS(1,2))

C

CRESLT = 'GOOD'

END

SUBROUTINE USER_SOURCE_SUB (NLOC,SOURCE,X,Y)

C

C .....

C

C ------------------------------

C Local Variables

C ------------------------------

INTEGER NLOC, ILOC

REAL SOURCE(NLOC), X(NLOC), Y(NLOC)

C------- --------------------------------------------------

C - 0.5 SOURCE = 1000.0

C - 3.5 SOURCE = -1000.0

C----- -------------------------------------------------- --

C ---------------------------

C Executable Statements

C ---------------------------

DO ILOC=1,NLOC

SOURCE(ILOC) = 0.0

IF

(X(ILOC).GE.0.5 .AND. X(ILOC).LE.1.5 .AND.

&

Y(ILOC).GE.1.25 .AND. Y(ILOC).LE.1.75) THEN

SOURCE(ILOC) = 1000.0

ELSE

IF

(X(ILOC).GE.3.5 .AND.

X(ILOC).LE.4.5 .AND.

&

Y(ILOC).GE.1.25 .AND. Y(ILOC).LE.1.75) THEN

SOURCE(ILOC) = -1000.0

END IF

END DO

C

END

User CEL Example 2: Using Gradients for an Additional Variable

Source

For

some

applications,

the

source

terms

for

the

transport

equations

might

depend

on

local

gradients.

Gradients

are

currently

not

supported

directly

within CEL. However, gradients of most variables can still be accessed

in

CEL

expressions

through

the

use

of

user

CEL

functions.

This

is

achieved

by

calling

the

utility

USER_GETVAR

with

the

‘Gradient'

operator

attached

to the variable name.

The

following

example

shows

the

use

of

a

source

term

depending

on

gradients

of one additional variable,

the transport equation of another additional variable,

.

, in