Description
Ramp function base class for the set of scalar functions starting from 0 and
increasing monotonically to 1 from \c start over the \c duration and
remaining at 1 thereafter.
Usage:
\verbatim
<entryName> <rampFunction>;
<entryName>Coeffs
{
start 10;
duration 20;
}
\endverbatim
or
\verbatim
<entryName>
{
type <rampFunction>;
start 10;
duration 20;
}
\endverbatim
Where:
\table
Property | Description | Required | Default value
start | Start time | no | 0
duration | Duration | yes |
\endtable
The following common ramp functions are provided: linear, quadratic, halfCosine,
quarterCosine and quaterSine, others can easily be added and registered to the run-time
selection system.
e.g.
ramp
{
type quadratic;
start 200;
duration 1.6;
}
but the old format is supported for backward compatibility:
ramp linear;
rampCoeffs
{
start 200;
duration 1.6;
}
e.g. in tutorials/heatTransfer/buoyantSimpleFoam/externalCoupledCavity/0/T
hot
{
type externalCoupledTemperature;
commsDir "${FOAM_CASE}/comms";
file "data";
initByExternal yes;
log true;
value uniform 307.75; // 34.6 degC
}
Previously both 'file' and 'fileName' were used inconsistently in different
classes and given that there is no confusion or ambiguity introduced by using
the simpler 'file' rather than 'fileName' this change simplifies the use and
maintenance of OpenFOAM.
This change requires that the de-reference operator '()' returns a
const-reference to the object stored irrespective of the const-ness of
object stored and the new member function 'ref()' is provided to return
an non-const reference to stored object which throws a fatal error if the
stored object is const.
In order to smooth the transition to this new safer 'tmp' the now
deprecated and unsafe non-const de-reference operator '()' is still
provided by default but may be switched-off with the compilation switch
'CONST_TMP'.
The main OpenFOAM library has already been upgraded and '-DCONST_TMP'
option specified in the 'options' file to switch to the new 'tmp'
behavior. The rest of OpenFOAM-dev will be upgraded over the following
few weeks.
Henry G. Weller
CFD Direct
with optional specification of the mark/space ratio
Templated square-wave function with support for an offset level.
\f[
a square(f (t - t_0)) s + l
\f]
where
\f$ square(t) \f$ is the square-wave function in range \f$ [-1, 1] \f$
with a mark/space ratio of \f$ r \f$
\vartable
symbol | Description | Data type | Default
a | Amplitude | Function1<scalar> |
f | Frequency [1/s] | Function1<scalar> |
s | Type scale factor | Function1<Type> |
l | Type offset level | Function1<Type> |
t_0 | Start time [s] | scalar | 0
r | mark/space ratio | scalar | 1
t | Time [s] | scalar
\endvartable
Example for a scalar:
\verbatim
<entryName> square;
<entryName>Coeffs
{
frequency 10;
amplitude 0.1;
scale 2e-6;
level 2e-6;
}
\endverbatim
Templated sine function with support for an offset level.
\f[
a sin(2 \pi f (t - t_0)) s + l
\f]
where
\vartable
symbol | Description | Data type
a | Amplitude | Function1<scalar>
f | Frequency [1/s] | Function1<scalar>
s | Type scale factor | Function1<Type>
l | Type offset level | Function1<Type>
t_0 | Start time [s] | scalar
t | Time [s] | scalar
\endvartable
Function1 is an abstract base-class of run-time selectable unary
functions which may be composed of other Function1's allowing the user
to specify complex functions of a single scalar variable, e.g. time.
The implementations need not be a simple or continuous functions;
interpolated tables and polynomials are also supported. In fact form of
mapping between a single scalar input and a single primitive type output
is supportable.
The primary application of Function1 is in time-varying boundary
conditions, it also used for other functions of time, e.g. injected mass
is spray simulations but is not limited to functions of time.
