SpecialBNDtreatmentEULERIMPL
(experimental) switch for special boundary treatment for MUSCL reconstruction in EULERIMPL scheme
Default:
SpecialBNDtreatmentEULERIMPL = (1,1,1)
If
EULERIMPL is used, then by default for all points close to the boundary it is checked if the auxiliary points for the MUSCL
reconstruction (see pure_TRANSPORT=1) are outside the domain. If an auxiliary point is outside, then the value of the nearest
boundary point is projected to the auxiliary point. Otherwise the auxiliary point is computed based on interior neighbor points.
In cases with long thin geometries, this treatment could lead to incorrect results because of the dominating effect of boundary
values. For example in a long thin tube, the auxiliary points are almost always outside the domain for each interior point. If
then the boundary values of the closest boundary points are always used, the boundary conditions overlay the interior domain.
This leads to non-physically fast in/decrease of temperature or/and wrong velocity profiles. Therefore in such cases it can be
helpful to switch off this treatment for single or even all quantities. It can be controlled by using the integer array
where the
first entry controls the
temperature , the
second one the
velocity and
the
third one the
k-epsilon model. The value 0 means that the boundary treatment is switched off and 1
means it is active. Thus (1,0,1) means that for temperature and k-epsilon the boundary treatment is active, whereas for the
velocity it is switched off. Furthermore it can help to reduce the number of points, which are marked near the boundary for
this treatment by skipping the second layer, see
SkipMarkingPointsLayer2. Moreover it is highly recommended to check the
influence of the parameter
StencilOrderReductionNearBND_forEULERIMPL. For long thin geometries it can be necessary in terms off
accuracy to switch off the stencil order reduction.
In order to switch off the entire boundary treatment for
EULERIMPL one must set:
Remark: But keep in mind that switching off this boundary treatment means that all auxiliary points for MUSCL are approximated
based on interior points, even if they are outside the domain!
Under
additionalPoint_approximation you will find the explanation for the approximation of the auxiliary points based on interior points.