hello and welcome
in this video we will discuss about how
to implement and set up periodic
boundaries using the ansys fluid meshing
watertight workflow
we will also explore the effect of the
different options available for the
setup periodic boundaries task on the
mesh
so let's get started
[Music]
open a new session of fluid meshing and
start a new water type geometry workflow
in import geometry task locate the
exercise file asymmetric periodic body
dot sc dock
and load it
in the local size input panel select yes
and define a curvature sizing control
select the three pipes in the label list
and set the curvature normal angle to 12
degrees
keep the other settings as default and
press the add local sizing button
the next step is to generate the surface
mesh
set a maximum size of 15 millimeters and
a minimum size of 5 millimeters
keep the other settings as default and
click on generate the surface mesh
as you can see for this model on the
periodic sides the mesh is refined in
the regions close to the pipes
this causes the mesh to be different on
the two sides making it asymmetric
now go to the task panel and right click
on the current task
go to insert new task and select setup
periodic boundaries to add the new task
let's explore the input panel
the type menu lets you select between
the two types of periodicities
rotational and translational
in this case we will use the rotational
one since the model is one-sixth of a
cylindrical geometry
under method we have two options
automatic pick box size
that lets you select the two periodic
boundaries and automatically detects the
angle and axis of rotation
or detractation vector
manual peak reference side instead
requires specifying the inputs for
rotation or translation relative to the
selected boundary
note that only manual method and label
selection are available if the setup
periodic boundaries task is executed
before degenerate the surface mesh task
let's use the automatic method and
select the labels side 1 and side 2.
note that only one couple of periodic
boundaries can be set for a model using
this workflow
in this case we grouped all the periodic
faces on each side under a common label
the last input of the task is remesh
asymmetric mesh boundaries
that gives us three options
auto that will let the software choose
whether to remesh the boundaries or not
yes that will enforce the remeshing
no they will avoid any remeshing
note that for the manual method the auto
option is not available
in this case let's skip the auto option
and complete the task
the green asterisk on the task tell us
that in the console panel there is a
warning message
different meshes were identified on the
two sides and remeshing was performed
this was our goal
any message tells us that we are on the
right path
indeed the mesh is now the same on the
two sides and the mesh on the adjacent
boundaries has been updated too
the remeshing can also be useful on
symmetric cases where the mesh side on
the boundary is stiffer due to the
effect of applied local sizings
if we will have selected the option no
instead we will have obtained this
result
dimension one of the sides gets copied
on the opposite boundary and local
refinements on the original mesh are
ignored
when using this option make sure that no
highly skewed cells
get created on the adjacent boundaries
the next task is to describe the
geometry
in this case select the second option
choose yes to change the fluid fluid
boundary types from wall to internal and
press describe geometry
in the update boundaries task you can
see that the two sides used for the
periodic boundaries are set as periodic
and shadow
upon import of the mesh in fluid solver
the two sides will be merged
into a single periodic boundary
condition
when using translational periodicity on
inlet outlet boundaries it is better to
avoid labels that trigger an automatic
boundary condition settings at this
stage so that the periodic and shadow
setting do not get overridden
at this point we can move directly to
degenerate the volume mesh task select
to fill with poly x core mesh
then set a minimal cell length to 2
millimeters and press the generate the
volume mesh button
all the previous tasks will be
automatically updated
as you can see
even after converting to polyhedral type
the mesh mapping is preserved on the two
periodic boundaries
let's summarize in this video we'll
learn how to implement and use the setup
periodic boundaries tasks in the fluent
meshing watertight workflow
while analyzing each item in the input
panel
we explore the effect of the remesh
asymmetric mesh boundaries option on the
mesh
using an asymmetric periodic geometry
we also understood the convenience of
grouping all the phases on each periodic
boundary under the same level
since only one
pair of periodic boundaries is supported
in this
workflow with that we have come to the
end of our video
you