CEPS: Extended syntax for input and inline parameters

General reading format

According to current files options a new way is introduced here to add some definitions of scalar constants, functions and other objects to be used as source terms, boundary conditions or physical coefficients. For the moment, the way to define some objects in the input file is quite simple and follows the following standard definition policy :

<main_keyword> : <value>...

Add to dictionary

Adding objects to the dictionary follows the same policy, that is to say a standardized policy using keywords and a lazy syntax for options under the main keyword DEFINE. In addition, extra rules are available here and follows the following general syntax

DEFINE : name [<field_type>] <options>

where the symbol [...] means that this argument is an option in some cases.

Details

A few field types are avalaible for the moment:

FIELD	string tag	Explanation
CONSTANT	CONSTANT	Hold a real constant
FUNCTION	FUNCTION	Hold a function, see below for more options
PIECEWISE	PIECEWISE	Define a piecewise scalar field
OPERATOR	OPERATOR	Define an operator between two objects or two constants
[ALIAS]	nothing	Not necessary but means that you attribute an alias for an internal already set object

Here are the possible options for each type:

<!-- Define an ALIAS to an internal object -->
DEFINE :  name    [ALIAS]        <internal_tag>
 
<!-- Define a real CONSTANT -->
DEFINE :  name    CONSTANT      <value>
 
<!-- Define a PIECEWISE variable -->
DEFINE :  name    PIECEWISE     [<attr_1> <value_1>] [<attr_2> <value_2>] ...
 
<!-- Define a new relation or an OPERATOR between two things -->
DEFINE :  name    OPERATOR      [<dico_tag_1>, <value>] [*, /, +, -] [<dico_tag_2>, <value>]
 
<!-- Define a FUNCTION which depends on time, space or solution u -->
DEFINE :  name    FUNCTION      [TIME <options>] [SPACE <options>] [UFUNC <options>]

Functions can be defined in different ways relative to the desired type. For now, three different types are avalaible and each type can be mixed with others

time function
space function
solution function where u is data from a DistributedVector.

For time and space functions you can use a predefined profile, known under the name of bell-type :

Type of bell	string TAG	Explanation
CONST	CONSTANT, CONST	constant bell
C4	C4, D4, 4	C4 bell
C5	C5, D5, 5	C5 bell
CINF	CINF, DINF, I	Cinf bell
GAUSSIAN	GAUSSIAN, GAUSS, G	gaussian bell
HEAVISIDE	HEAVISIDE, HEAVY, H	heaviside bell
RECTANGLE	RECTANGLE, REC, R	rectangle bell

List of options for <tt>TIME</tt> to create time functions

Create an time function (aka ) is very simple with this syntax. All parameters are optional.

<!-- Definition for activation function : f(t) -->
DEFINE : name     FUNCTION      TIME  PROFILE     <bell_type>   \\
                                      START       <time_start>  \\
                                      END         <time_end>    \\
                                      DURATION    <duration>    \\
                                      PERIOD      <period>      \\
                                      SCALE       <scale>

with default values

<time_start>  =  0.0    <!-- means 'start at 0.0'-->
<time_end>    =  5000.0 <!-- means 'end at 0.0'-->
<duration>    =  0.0    <!-- means 'activate during 0.0'-->
<period>      = -1.0    <!-- means 'no periodicity'-->
<scale>       =  1.0    <!-- means 'factor of amplitude is 1.0'-->

In addition you can, here again, define your excitation time function by internal tag like

DEFINE : name FUNCTION TIME <internal_tag>

List of options for <tt>SPACE</tt> to create space functions

If you want to create a space function, an activation function with a space bell, you can in addition create a spatial bell function (the name here is generic for centralized spatial function) like

<!-- Definition for stimulation -->
DEFINE :  name    FUNCTION      SPACE PROFILE   <bell_type>       \\
                                      CENTER    <ox> <oy> <oz>    \\
                                      DIAMETER  <diameter>        \\
                                      SCALE     <scale>

with default values

<bell_type>    =  "C4"         <!-- means 'constant bell'-->
<ox> <oy> <oz> =  0.0 0.0 0.0  <!-- means 'center at origin 0.0 0.0 0.0'-->
<diameter>     =  1.0          <!-- means 'diameter is 1.0'-->
<scale>        =  1.0          <!-- means 'factor is 1.0'-->

In addition you can, here again, define your spatial function by internal tag like

DEFINE : name FUNCTION SPACE <internal_tag>

List of options for <tt>UFUNC</tt> to create solution functions

For now, you can only used predefined solution function (internal tag) like

DEFINE : name FUNCTION UFUNC <internal_tag>

Add a source term

Add a source term from its definition in the dictionary is quite simple and you can add some extra options. You can set the source term type like : DEFAULT, KTERM, IAPP

SOURCE_TERM : name <dico_tag>              \\
              COMPONENT  <component>       \\
             [TYPE       <st_type>         \\]
             [ATTRIBUTE  <attr>            \\]
             [SCALE      <factor>           ]

by default no restriction are enabled, the scale is 1.0 and TYPE is DEFAULT, component default is 0.

Add boundary condition

In the same way, you can set any boundary condition with some extra options

BOUNDARY_CONDITION : name <BC_TYPE> <dico_tag>          \\
                     COMPONENT  <component>             \\
                    [ATTRIBUTE        <attr>            \\]
                    [MESH_DIMENSION   <dimension>       \\]
                    [SCALE            <factor>          \\]
                    [VOLUMIC                             ]]

with the same default value for scale factor (1.0) and no restriction, component default is 0 and the searching mesh dimension is the higher presented mesh by default.

The options for BC_TYPE are DIRICHLET, NEUMANN and ROBIN.

A special consideration is made for DIRICHLET boundary conditions : if the VOLUMIC keyword is present so we are searching node with attribute ATTRIBUTE inside the domain. In other cases, (NEUMANN or ROBIN) this keyword has no effect and we considere only boundary nodes/elements.

Some examples

Here some examples :

// dico definitions
 
// define constant everywhere
DEFINE  : j_e CONSTANT 2.6 // define constant everywhere
 
// define a stimulation function
DEFINE  : stim1 FUNCTION SPACE PROFILE     CINF                       \\
                               CENTER      -1.48443 -19.2075 18.6753  \\
                               DIAMETER    1.0                        \\
                               SCALE       1.0                        \\
                         TIME  PROFILE     CINF                       \\
                               START       1.0                        \\
                               END         15.0                       \\
                               DURATION    1.0                        \\
                               PERIOD      -1
 
// define an excitation function from internal tag
DEFINE  : act1 FUNCTION TIME sin(t)
 
// define an excitation function from parameters
DEFINE  : act2 FUNCTION TIME START     15.0 \\
                             END       0.1  \\
                             DURATION  1.0  \\
                             PERIOD    -1   \\
                             SCALE     1.0
 
// define an object read from file
DEFINE  : ue2 FILE ./ue2.dat
 
// define a new relation/operator between two objects
DEFINE  : Hue2 OPERATOR act1 * ue2
 
// define an alias for some internal object
DEFINE  : chi standard_chi
 
// insert source terms and boundary conditions in the solver
 
// define a stimulation source term from dictionary object named 'stim' and restrict it to attribute 200 and on component 0
SOURCE_TERM         : stim stim COMPONENT 0 ATTRIBUTE 200 TYPE IAPP
 
// define another source term from dictionary of type KTERM on attribute 200
SOURCE_TERM         : Hue2  Hue2 COMPONENT 0 ATTRIBUTE 200 TYPE KTERM
 
// define an external boundary condition on entire boundary
BOUNDARY_CONDITION  : external NEUMANN Hue2 COMPONENT 0