View source for Presets/symmetry.xml

== Introduction ==

symmetry.xml is a preset used to define symmetric boundary conditions, such that all the particles close enough to such boundaries is interaction with a mirrored fluid extension as well.

== Usage ==

To use it the following tag should be added to include the preset:

<syntaxhighlight lang="xml">
<Include file="/usr/share/aquagpusph/resources/Presets/symmetry.xml" />
</syntaxhighlight>

Where <tt>/usr/share/aquagpusph/</tt> should be conveniently modified.

After that, the symmetry plane should be modified. For instance, to set the plane <math>x=-1</math>, the following code snippet can be used:

<syntaxhighlight lang="xml">
<Variables>
    <Variable name="symmetry_r" type="vec" value="-1.0, 0.0, 0.0, 0.0" />
    <Variable name="symmetry_n" type="vec" value="1.0, 0.0, 0.0, 0.0" />
</Variables>
</syntaxhighlight>

However, in some cases several mirroring planes should be set (see [[Examples/2D/souto_etal_2012_standingwave|Standing Wave example]]). In such case prefix can be used:

<syntaxhighlight lang="xml">
<sphInput>
    <Include file="@RESOURCES_DIR@/Presets/symmetry.xml" prefix="left_"/>
    <Include file="@RESOURCES_DIR@/Presets/symmetry.xml" prefix="right_"/>

    <Tools>
        <Tool action="insert" before="left_SymmetryMirror" type="set_scalar" name="left_symmetry_r" in="symmetry_r" value="-1.0, 0.0, 0.0, 0.0"/>
        <Tool action="insert" after="left_symmetry_r" type="set_scalar" name="left_symmetry_n" in="symmetry_n" value="-1.0, 0.0, 0.0, 0.0"/>
        <Tool action="insert" before="right_SymmetryMirror" type="set_scalar" name="right_symmetry_r" in="symmetry_r" value="1.0, 0.0, 0.0, 0.0"/>
        <Tool action="insert" after="right_symmetry_r" type="set_scalar" name="right_symmetry_n" in="symmetry_n" value="1.0, 0.0, 0.0, 0.0"/>
    </Tools>
</sphInput>
</syntaxhighlight>

In this case we are including two times the preset, inserting different prefixes to each one, such that later we can insert a couple of tools to modify the variables <tt>symmetry_r</tt> and <tt>symmetry_n</tt> (position and normal of the symmetry plane) right before the symmetry plane boundary condition is executed.

Hence, in the previous example 2 symmetry planes are set, <math>x=-1</math> and <math>x=1</math>.

As it can be appreciated, '''outward normal should be imposed'''.

This preset should be loaded after [[Presets/cfd.xml|cfd.xml]].

== Variables defined ==

When this preset is loaded some variables are generated (on top of the [[Variables|default variables of AQUAgpusph]]):

{| class="wikitable" style="text-align: left; width: 800px;"
| NAME
| TYPE
| LENGTH
| DESCRIPTION
|-
| symmetry_r
| vec
| 1
| Position of the plane.
|-
| symmetry_n
| vec
| 1
| Outward normal of the plane.
|-
| imirrored
| int*
| N
| Flag to identify the particles to be symmetrized
|-
| rmirrored
| vec*
| N
| New position, <math>\mathbf{r}</math>, of the mirrored particles
|-
| umirrored
| vec*
| N
| New velocity, <math>\mathbf{u}</math>,  of the mirrored particles
|-
| nmirrored
| vec*
| N
| New normal, <math>\mathbf{n}</math>,  of the mirrored particles
|}

== Definitions ==

This preset is not adding new definitions (see [[Definitions|Definitions]]).

== Tools ==

The following tools are set to be executed each time step, right before the [[Presets/cfd.xml#Tools|"BoundaryIntegrals" tool]]. (see [[Tools|Tools]] and [[Presets/cfd.xml|cfd.xml]] to learn more about this):

{| class="wikitable" style="text-align: left; width: 800px;"
| NAME
| TYPE
| DESCRIPTION
|-
| SymmetryMirror
| [[Tools#kernel|kernel]]
| Look for the particles close enough to the symmetry boundary setting <tt>imirrored</tt>, <tt>rmirrored</tt> and <tt>nmirrored</tt> (see [[#Variables defined|the variables defined]]).
|-
| SymmetryInteractions
| [[Tools#kernel|kernel]]
| Compute the interactions between the particles close enough to the symmetry boundary, and the fluid extension.
|-
| SymmetryBoundaryIntegrals
| [[Tools#kernel|kernel]]
| Compute the interactions between the particles close enough to the symmetry boundary, and the eventually mirrored boundary elements.
|}

== Reports ==

This preset is not adding new reports (see [[Reports|Reports]]).

[[Category:Simulation Setup]]
[[Category:Presets]]
[[Category:Variables]]
[[Category:Tools]]