Difference between revisions of "Grid BC Shape Commands"

Latest revision as of 11:01, 8 April 2017

The method to create grid-based boundary conditions was changed in NairnMPM (April 2017) and OSParticulas (revision 1170) to the method using GridBC and <BCShape> blocks. As a result, all boundary condition commands listed below are deprecated. They still work, but should be replaced by new methods as described below.

Line (2D or Axisymmetric)

The command to select a line through a 2D mesh in scripted files:

MoveLine (x1),(y1),(x2),(y2),<(tolerance)>
  (one or more velocity, temperature, or concentration condition)
EndMoveLine

should be replaced by (and note change in order of parameters):

GridBC
  Line (x1),(x2),(y1),(y2),<(tolerance)>
  (one or more velocity, temperature, or concentration condition)
EndGridBC

In XML files, a line selected with:

<BCLine units='(units)' x1='(x1)' y1='(y1)' x2='(x2)' y2='(y2)' tolerance='(tolerance)'>
  (one or more velocity, temperature, or concentration condition)
</BCLine>

should be replaced by:

<BCShape>
  <Line x1='(x1)' y1='(y1)' x2='(x2)' y2='(y2)' tolerance='(tolerance)'>
  (one or more velocity, temperature, or concentration condition)
</BCShape>

Arc (2D or Axisymmetric)

The command to select an arc through a 2D mesh in scripted files:

MoveArc (x1),(y1),(x2),(y2),(startAng),(endAng),<(tolerance)>
  (one or more velocity, temperature, or concentration condition)
EndMoveLine

should be replaced by (and note change in order of parameters):

GridBC
  Arc (x1),(x2),(y1),(y2),(startAng),(endAng),<(tolerance)>
  (one or more velocity, temperature, or concentration condition)
EndGridBC

In XML files, an arc selected with:

<BCArc units='(units)' x1='(x1)' y1='(y1)' x2='(x2)' y2='(y2)'
       start='(startAng)' end='(endAng)' tolerance='(tolerance)'>
  (one or more velocity, temperature, or concentration condition)
    ...
</BCLine>

should be replaced by

<BCShape>
   <Arc x1='(x1)' y1='(y1)' x2='(x2)' y2='(y2)'
            start='(startAng)' end='(endAng)' tolerance='(tolerance)'>
  (one or more velocity, temperature, or concentration condition)
</BCShape>

Rectangle (2D or Axisymmetric)

The command to select a rectangle (which is only available in XML files)

<LdRect xmin='(xmin)' xmax='(xmax)' ymin='(ymin)' ymax='(ymax)'>
  (one or more velocity, temperature, or concentration condition)
</LdRect>

should be replaced by

<BCShape>
  <Rect xmin='(xmin)' xmax='(xmax)' ymin='(ymin)' ymax='(ymax)'>
  (one or more velocity, temperature, or concentration condition)
</BCShape >

Box or Cylinder (3D)

The command to select a 3D box or cylinder in scripted files:

MoveBox (x1),(y1),(z1),(x2),(y2),(z2),<(axis)>
  (one or more velocity, temperature, or concentration condition)
EndMoveBox

should be replaced by (and note change in order of parameters):

GridBC
  Box (x1),(x2),(y1),(y2),(z1),(z1)
  (one or more velocity, temperature, or concentration condition)
EndGridBC

In XML files, a box or cylinder is selected with:

<BCBox units='(units)' xmin='(x1)' xmax='(x2)' ymin='(y1)' ymax='(y2)'
                       zmin='(z1)' zmax='(z2)' axis='(axis)'>
  (one or more velocity, temperature, or concentration condition)
</BCBox>

should be replaced by

<BCShape>
   <Box units='(units)' xmin='(x1)' xmax='(x2)' ymin='(y1)' ymax='(y2)'
                       zmin='(z1)' zmax='(z2)' axis='(axis)'>
  (one or more velocity, temperature, or concentration condition)
</BCShape>

Difference between revisions of "Grid BC Shape Commands"

Latest revision as of 11:01, 8 April 2017

Contents

Line (2D or Axisymmetric)

Arc (2D or Axisymmetric)

Rectangle (2D or Axisymmetric)

Box or Cylinder (3D)

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@@ Line 1: / Line 1: @@
-The method to create grid-based boundary conditions was changed in [[NairnMPM]] (April 2017) and [[OSParticulas]] (revision 1170) to the method described [[Grid-Based Boundary Conditions||<tt><tt>GridBC</tt> and <tt>&lt;BCShape&gt;</tt> blocks]]. As a result, all boundary conditions commands listed below are deprecated. They still work, but should be replaced by new methods as described below.
+The method to create grid-based boundary conditions was changed in [[NairnMPM]] (April 2017) and [[OSParticulas]] (revision 1170) to the method using [[Grid-Based Boundary Conditions|<tt>GridBC</tt> and <tt>&lt;BCShape&gt;</tt> blocks]]. As a result, all boundary condition commands listed below are deprecated. They still work, but should be replaced by new methods as described below.
 == Line (2D or Axisymmetric) ==
@@ Line 77: / Line 77: @@
 == Box or Cylinder (3D) ==
-The command to select a 3D box or cylinder in scripted files is:
+The command to select a 3D box or cylinder in scripted files:
   MoveBox (x1),(y1),(z1),(x2),(y2),(z2),<(axis)>
     (one or more velocity, temperature, or concentration condition)
-     ...
   EndMoveBox
+should be replaced by (and note change in order of parameters):
+ GridBC
+   Box (x1),(x2),(y1),(y2),(z1),(z1)
+   (one or more velocity, temperature, or concentration condition)
+ EndGridBC
 In <tt>XML</tt> files, a box or cylinder is selected with:
@@ Line 89: / Line 95: @@
                          zmin='(z1)' zmax='(z2)' axis='(axis)'>
     (one or more velocity, temperature, or concentration condition)
-     ...
   </BCBox>
-where
+should be replaced by
-* <tt>(x1, y1, z1)</tt> and <tt>(x2, y2, z2)</tt> define <tt>(x, y, z)</tt> coordinates for opposite corners of the box. The units are [[ConsistentUnits Command#Legacy and Consistent Units|length units]] (or determined by a [[Units Attribute|units attribute]] in <tt>XML</tt> files). In <tt>XML</tt> files, the coordinates can alternatively be specified [[#Relative Grid Locations|relative to the mesh edges]].
+ <BCShape>
-* <tt>(axis)</tt> is an optional parameter that will convert the shape from a box to the cylinder enclosed within the box with its axis along the specified direction (entered as x, 1, y, 2, z, or 3).
+    <Box units='(units)' xmin='(x1)' xmax='(x2)' ymin='(y1)' ymax='(y2)'
+                        zmin='(z1)' zmax='(z2)' axis='(axis)'>
-This command will apply [[Setting Velocity, Temperature, and Concentration|velocity, temperature, and/or concentration boundary conditions]] to all nodes within the specified box or cylinder.
+   (one or more velocity, temperature, or concentration condition)
+  </BCShape>
-== Relative Grid Locations ==
-Rather than hard code positions for boundary conditions or shapes that define material points, any coordinate specified in <tt>XML</tt> files (''e.g''., an entry for <tt>(x1)</tt>, <tt>(x2)</tt>, <tt>(xmin)</tt>, <tt>(xmax)</tt>, ''etc.'') can be the text <tt>'min'</tt>, <tt>'max'</tt>, <tt>'min-3'</tt>, <tt>'min+1.2'</tt>, <tt>'max-3.8'</tt>, <tt>'max+2'</tt>, ''etc.'', meaning the minimum, the maximum, or a specified number of cells relative to the minimum or maximum of the [[MPM Grid Generation|current mesh]]. For [[MPM Methods and Simulation Timing|GIMP calculations]] <tt>'min'</tt> and <tt>'max'</tt> will be limits of useable mesh while <tt>'min-1'</tt> and <tt>'max+1'</tt> will be limits to the total mesh. For backward compatibility, <tt>min+</tt>, <tt>min-</tt>, <tt>max+</tt>, and <tt>max-</tt> refer to plus or minus one cell from the minimum or maximum of the current mesh.
-== Layers of Boundary Conditions ==
-Grid boundary conditions are typcially placed one a layer of nodes that is outside the body defined by the material points and that layer defines the boundary. When using [[MPM Methods and Simulation Timing|GIMP methods]], however, a particle near the boundary will interact with that boundary layer, but may also interact with nodes beyond a single row of boundary conditions. To prevent non-physical results from the extra nodes that are physcially outside the body, it may be necessary to set up two rows (or columns) of boundary conditions. For example, to have a rigid wall, set the velocity of two rows (or columns) or nodes to be zero. An alternative solution is to fill a boundary area with  [[Rigid Material|rigid particles]]. Rigid particle automatically create the required boundary conditions on two rows (or columns) of nodes.
-Sometimes even two rows of boundary conditions will lead to artifacts in particles near the edges. These artifacts can be reduced by using  [[MPM Grid Generation#Symmetry Planes|symmetry planes]] or [[Rigid Material|rigid particles]] with the <tt>mirrored</tt> property.