Description
Evaluates and writes the turbulence intensity field 'I'.
The turbulence intensity field 'I' is the root-mean-square of the turbulent
velocity fluctuations normalised by the local velocity magnitude:
\f[
I \equiv \frac{\sqrt{\frac{2}{3}\, k}}{U}
\f]
To avoid spurious extrema and division by 0 I is limited to 1 where the
velocity magnitude is less than the turbulent velocity fluctuations.
Example of function object specification:
\verbatim
functions
{
.
.
.
turbulenceIntensity
{
type turbulenceIntensity;
libs ("libfieldFunctionObjects.so");
}
.
.
.
}
\endverbatim
or using the standard configuration file:
\verbatim
functions
{
.
.
.
#includeFunc turbulenceIntensity
.
.
.
}
\endverbatim
This change means that getApplication still works if we have a
controlDict.orig, rather than a controlDict. This allows us to simplify
the scripting of tutorials in which the controlDict is modified.
Minmod is the default limiter function and specified with an explicit name e.g.:
gradSchemes
{
default Gauss linear;
limited cellLimited Gauss linear 1;
}
Venkatakrishnan and cubic limiter functions are also provided and may be
specified explicitly e.g.:
gradSchemes
{
default Gauss linear;
limited cellLimited<Venkatakrishnan> Gauss linear 1;
}
or
gradSchemes
{
default Gauss linear;
limited cellLimited<cubic> 1.5 Gauss linear 1;
}
The standard minmod function is recommended for most applications but if
convergence or stability problems arise it may be beneficial to use one of the
alternatives which smooth the gradient limiting. The Venkatakrishnan is not
well formulated and allows the limiter to exceed 1 whereas the cubic limiter is
designed to obey all the value and gradient constraints on the limiter function,
see
Michalak, K., & Ollivier-Gooch, C. (2008).
Limiters for unstructured higher-order accurate solutions
of the Euler equations.
In 46th AIAA Aerospace Sciences Meeting and Exhibit (p. 776).
The cubic limiter function requires the transition point at which the limiter
function reaches 1 is an input parameter which should be set to a value between
1 and 2 although values larger than 2 are physical but likely to significantly
reduce the accuracy of the scheme.
The tutorial demonstrates generation of a C-grid mesh using blockMesh
The geometry is provided by a surface mesh (OBJ file) of the NACA0012 aerofoil
The case is setup with a freestream flow speed of Ma=0.72
Thanks to Kai Bastos at Duke University for the geometry and helpful input.
Some tutorials have had Allrun scripts added in order to run setFields,
which was previously omitted. Others have had nonuniform field files in
the 0 directory replaced by uniform files with .orig extensions.
These BCs blend between typical inflow and outflow conditions based on the
velocity orientation.
airFoil2D tutorial updated to demonstrate these new BCs.
Without -fields specified mergeOrSplitBaffles now manipulates the mesh only and
with the -fields option also updates the fields corresponding to the mesh change.
Now if a <field> file does not exist first the compressed <field>.gz file is
searched for and if that also does not exist the <field>.orig file is searched
for.
This simplifies case setup and run scripts as now setField for example can read
the <field>.orig file directly and generate the <field> file from it which is
then read by the solver. Additionally the cleanCase function used by
foamCleanCase and the Allclean scripts automatically removed <field> files if
there is a corresponding <field>.orig file. So now there is no need for the
Allrun scripts to copy <field>.orig files into <field> or for the Allclean
scripts to explicitly remove them.
This is a CHT case which uses snappyHexMesh. It is a tutorial, in the
traditional sense, in that it has been designed for training purposes.
It does not rely on changeDictionary, surface utilities, or extensive
scripting.
This work was supported by Colin Moughton, at Strix
A lower limit of one on the number of particles represented by a single
parcel has been removed from the injection models. It may be appropriate
to simulate the statistical behaviour of a particulate flow with more
lagrangian elements than physical particles. A unity lower limit does
not permit this.
The limit was, in some situations, also causing the large-diameter end
of an injected distribution to be clipped.
This resolves bug report https://bugs.openfoam.org/view.php?id=2837
The logic governing function objects' ability to change the time-step
has been modified so that it is compatible with the time-step adjustment
done in the Time class. The behaviour has been split into a method which
sets the step directly, and another which moidifies the time until the
next write operation (i.e., the time that the solver "aims" for).
This fixes an issue where the adjustments in Time and the function
objects interfere and cause the time step to decrease exponentially down
to machine precision. It also means that the set-time-step function
object now does not break the adjustable run-time setting.
This resolves bug report https://bugs.openfoam.org/view.php?id=2820
