There is a need to specify const or non-const access to a non-const
object which is not currently possible with the "boundaryField()" access
function the const-ness of the return of which is defined by the
const-ness of the object for which it is called. For consistency with
the latest "tmp" storage class in which non-const access is obtained
with the "ref()" function it is proposed to replace the non-const form
of "boundaryField()" with "boundaryFieldRef()".
Thanks to Mattijs Janssens for starting the process of migration to
"boundaryFieldRef()" and providing a patch for the OpenFOAM and
finiteVolume libraries.
This condition creates a zero-dimensional model of an enclosed volume of
gas upstream of the inlet. The pressure that the boundary condition
exerts on the inlet boundary is dependent on the thermodynamic state of
the upstream volume. The upstream plenum density and temperature are
time-stepped along with the rest of the simulation, and momentum is
neglected. The plenum is supplied with a user specified mass flow and
temperature.
The result is a boundary condition which blends between a pressure inlet
condition condition and a fixed mass flow. The smaller the plenum
volume, the quicker the pressure responds to a deviation from the supply
mass flow, and the closer the model approximates a fixed mass flow. As
the plenum size increases, the model becomes more similar to a specified
pressure.
The expansion from the plenum to the inlet boundary is controlled by an
area ratio and a discharge coefficient. The area ratio can be used to
represent further acceleration between a sub-grid blockage such as fins.
The discharge coefficient represents a fractional deviation from an
ideal expansion process.
This condition is useful for simulating unsteady internal flow problems
for which both a mass flow boundary is unrealistic, and a pressure
boundary is susceptible to flow reversal. It was developed for use in
simulating confined combustion.
tutorials/compressible/rhoPimpleFoam/laminar/helmholtzResonance:
helmholtz resonance tutorial case for plenum pressure boundary
This development was contributed by Will Bainbridge
Also added the new prghTotalHydrostaticPressure p_rgh BC which uses the
hydrostatic pressure field as the reference state for the far-field
which provides much more accurate entrainment is large open domains
typical of many fire simulations.
The hydrostatic field solution is controlled by the optional entries in
the fvSolution.PIMPLE dictionary, e.g.
hydrostaticInitialization yes;
nHydrostaticCorrectors 5;
and the solver must also be specified for the hydrostatic p_rgh field
ph_rgh e.g.
ph_rgh
{
$p_rgh;
}
Suitable boundary conditions for ph_rgh cannot always be derived from
those for p_rgh and so the ph_rgh is read to provide them.
To avoid accuracy issues with IO, restart and post-processing the p_rgh
and ph_rgh the option to specify a suitable reference pressure is
provided via the optional pRef file in the constant directory, e.g.
dimensions [1 -1 -2 0 0 0 0];
value 101325;
which is used in the relationship between p_rgh and p:
p = p_rgh + rho*gh + pRef;
Note that if pRef is specified all pressure BC specifications in the
p_rgh and ph_rgh files are relative to the reference to avoid round-off
errors.
For examples of suitable BCs for p_rgh and ph_rgh for a range of
fireFoam cases please study the tutorials in
tutorials/combustion/fireFoam/les which have all been updated.
Henry G. Weller
CFD Direct Ltd.
The joint-space dynamics is solved on the master processor only and the
resulting joint-state distributed to the slave processors on which the
body-state is then updated. This guarantees consistency of the body
position and orientation on all processors.
The motion of the bodies is integrated using the rigidBodyDynamics
library with joints, restraints and external forces.
The mesh-motion is interpolated using septernion averaging.
This development is sponsored by Carnegie Wave Energy Ltd.
inline Foam::vector Foam::septernion::transformPoint(const vector& v) const
{
return r().transform(v - t());
}
Now there is a 1:1 correspondence between septernion and
spatialTransform and a septernion constructor from spatialTransform
provided.
Additionally "septernion::transform" has been renamed
"septernion::transformPoint" to clarify that it transforms coordinate
points rather than displacements or other relative vectors.
'w' is now obtained from 'v' using the relation w = sqrt(1 - |sqr(v)|)
and 'v' is stored in the joint state field 'q' and integrated in the
usual manner but corrected using quaternion transformations.
Currently supported solvers: symplectic, Newmark, CrankNicolson
The symplectic solver should only be used if iteration over the forces
and body-motion is not required. Newmark and CrankNicolson both require
iteration to provide 2nd-order behavior.
See applications/test/rigidBodyDynamics/spring for an example of the
application of the Newmark solver.
This development is sponsored by Carnegie Wave Energy Ltd.
This is a more convenient way of maintaining the state or multiple
states (for higher-order integration), storing, retrieving and passing
between processors.
Included for backward-compatibility with the 6-DoF solver but in the
future will be re-implemented as a joint rather than body restraint and
accumulated in tau (internal forces) rather than fx (external forces).
applications/test/rigidBodyDynamics/spring: Test of the linear spring with damper restraint
Damped simple harmonic motion of a weight on a spring is simulated and
the results compared with analytical solution
Test-spring
gnuplot spring.gnuplot
evince spring.eps
This development is sponsored by Carnegie Wave Energy Ltd.
