Description
This fvModel applies forcing to the liquid phase-fraction field and all
components of the vector field to relax the fields towards those
calculated from the current wave distribution.
The force coefficient \f$\lambda\f$ should be set based on the desired level
of forcing and the residence time the waves through the forcing zone. For
example, if waves moving at 2 [m/s] are travelling through a forcing zone 8
[m] in length, then the residence time is 4 [s]. If it is deemed necessary
to force for 5 time-scales, then \f$\lambda\f$ should be set to equal 5/(4
[s]) = 1.2 [1/s]. If more aggressive forcing is required adjacent to the
boundaries, which is often the case if wave boundary conditions are
specified at outflow boundaries, the optional \f$\lambdaBoundary\f$
coefficient can be specified higher than the value of \f$\lambda\f$.
Alternatively the forcing force coefficient \f$\lambdaCoeff\f$ can be
specified in which case \f$\lambda\f$ is evaluated by multiplying the
maximum wave speed by \f$\lambdaCoeff\f$ and dividing by the forcing region
length. \f$\lambdaBoundary\f$ is similarly evaluated from
\f$\lambdaBoundaryCoeff\f$ if specified.
Usage
Example usage:
\verbatim
waveForcing1
{
type waveForcing;
libs ("libwaves.so");
liquidPhase water;
// Define the line along which to apply the graduation
origin (600 0 0);
direction (-1 0 0);
// // Or, define multiple lines
// origins ((600 0 0) (600 -300 0) (600 300 0));
// directions ((-1 0 0) (0 1 0) (0 -1 0));
scale
{
type halfCosineRamp;
start 0;
duration 300;
}
lambdaCoeff 2; // Forcing coefficient
// lambdaBoundaryCoeff 10; // Optional boundary forcing coefficient
// Useful when wave BCs are specified at outlets
// Write the forcing fields: forcing:scale, forcing:forceCoeff
writeForceFields true;
}
\endverbatim
e.g.
waveForcing1
{
type waveForcing;
libs ("libwaves.so");
liquidPhase water;
// Define the line along which to apply the graduation
origin (600 0 0);
direction (-1 0 0);
// // Or, define multiple lines
// origins ((600 0 0) (600 -300 0) (600 300 0));
// directions ((-1 0 0) (0 1 0) (0 -1 0));
scale
{
type halfCosineRamp;
start 0;
duration 300;
}
lambda 0.5; // Forcing coefficient
// lambdaBoundary 2; // Optional boundary forcing coefficient
// Useful when wave BCs are specified
// without mean flow
// Write the forcing fields: forcing:scale, forcing:forceCoeff
writeForceFields true;
}
will write the fields forcing:scale and forcing:forceCoeff at the start of the
run to visualise and check correctness.
Simplifications have been made where possible, as permitted by the new
$<type>var syntax. Duplication has been reduced in similar blockMesh
files (e.g., sloshingTank cases). Settings that cannot practically be
changed have been hard-coded (e.g., angle in the mixerVessel2D
blockMeshDict). The rotor2D blockMeshDict has been centralised and
extended to work with an arbitrary number of rotor blades.
If the libs entry is not provided and the name of the library containing the
functionObject, fvModel or fvConstraint corresponds to the type specified the
corresponding library is automatically loaded, e.g. to apply the
VoFTurbulenceDamping fvModel to an incompressibleVoF simulation the following
will load the libVoFTurbulenceDamping.so library automatically and instantiate
the fvModel:
turbulenceDamping
{
type VoFTurbulenceDamping;
delta 1e-4;
}
which allows lambda to set higher in the cells adjacent to the boundary which is
particularly useful when solving for waves in a domain with no mean-flow and
wave BCs to avoid numerical stability problems where the specified wave flow
reverses into the domain. The alternative is to use symmetry rather than wave
BCs on the side patches which is stable without using lambdaBoundary but there
is modest distortion of the wave profile adjacent to the side patches which does
not propagate into the domain due to the wave forcing.
