LaGriT/documentation/lagrit_manual/commands/stack.txt

.. _stack:

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## STACK

> The **stack/layers** command is used to read surfaces and merge into a
single stacked layers cmo. The surfaces must have the same number of nodes,
and the x,y coordinates of each layer must be the same. (i.e. x_n,y_n of
surface M must equal x_n,y_n of surface N), and the surfaces must be single
valued functions of z. The layers are stacked with the first file on the
bottom, last file is the top surface. The lower elevation of each layer
truncates the upper. The second from last surface can be made to truncate all
lower surfaces, commonly done with a topographic surface.

  
The **stack/layers** command adds three scalar attributes that are used in the
**stack/fill** command. See syntax below. nlayers are the total number of
layers in the stacked cmo, this includes layers added for refinement.
nnperlayer are the number of nodes in each of the layers. neperlayer are the
number of elements in each of the layers.

>

>> The node attribute VINT layertyp is created to indicate what type of layer
each node is in.

-1 bottom surface   
-2 top surface   
0 original input surfaces (usually interfaces)

1 derived surface to buffer interfaces

2 derived surface added as refinement layer

>

>

The **layers** option is followed by a list of surface files and their
material numbers. Further options include the file_type either AVS or GMV,
layer_refinement and pinch_options.

  
**stack/layers/** file_type / [xy_subset] / file_list / [buffer_opt] [truncate_opt] [pinchout_opt] [flip_opt] 

  
  
file_type  The third parameter indicates the type of files to read as
surfaces.

> _**avs**_ will read AVS UCD files as a surfaces.

**gmv** will read GMV files as a surfaces. 

  
xy_subset  This option allows a subset of the surfaces to be used. The syntax
is  minx, miny, maxx, maxy

  
  
file_list  This is the list of files to read from bottom surface to top. Each
surface can be followed by an integer value to indicate a material number, and
an integer value to indicate the number of layers to add as refinement between
input surfaces. The file list has this syntax:  file1 mat_num, file2 mat_num
[ref_num], file3 mat_num [ref_num] ...

> file1 thru filen can be quad or tri surface files.

mat_num  is the material number for the unit defined by upper and lower
surface. These values will detirmine the element colors when the layers are
filled with element volumes.

ref_num is the number of refinement layers to add between two surfaces.
Refinement is done proportionallly, creating new layers between the choosen
surfaces. The first filename can not have a refinement number, units start at
second file name. See examples below.

  
buffer_option  This optional parameter creates buffer layers around interfaces
at a distance equal to xvalue. It derives layers above and below each surface
that is read in to the stack routine. Buffers are not created around
refinement layers or on the top and bottom surfaces. The buffer option has
this syntax: **buffer** xvalue

  
  
truncate_option  This optional parameter causes all layers below the choosen
surface to be truncated. The truncating surface is indicated by the integer
number. For instance 5 will truncate all layers below the 5th surface by the
5th surface. **trunc** nth_file

  
  
pinchout_options  These optional parameters control how layers are pinched out
where they cross. They will also help to control the minimum thickness in a
unit between layers.

> **pinch** xthick  real value xthick  is mininum thickness allowed in a
layer. This allows upper surface elevation to be equal to ower surface
elevation if upper surface dips below lower surface. By default, **pinch** is
set to 0.

**dpinch** dvalue  **dmin** mvalue  These options are used along with buffers to help elements to follow the interface boundarys. These options differ from the simple **pinch** option. This option uses the beads_ona_ring algrithm to move points vertically after all the layers are stacked.   
If layer thickness <= dvalue then thickness is set to zero.

If layer thickness is < dvalue < mvalue, set thickness to mvalue.

(default dvalue = mvalue = 0.0, no post processing)

  
** flip ** optional parameter will flip elements so the normals point positive Z direction.   
  
  
**stack/fill** / cmo_3D / cmo_stack    
is a command used after the files are stacked into a single cmo. The units are
filled between the layers with 3D elements. For triangulated surfaces, the
elements will be prisms, and for quad sheets the filler elements will be hex.

  
  
  
FORMAT:

> ** stack/layers **

** [avs | gmv ] **   
[minx,miny, maxx,maxy]

filename(1) [matno] filename(i) [matnum, addnum] filename(n) [matnum, addnum]
**[ flip ]**

** [ buffer **[xdistance] ]   
** [ pinch** font face="Courier New,Courier">[xthick] ]   
**[ trunc** [ifile]   
**[ dpinch **xvalue /   
**dmin **xvalue ]   
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EXAMPLES:

> cmo create cmo_stack

**stack/layers/avs**/ fsrf575.inp&nbsp_place_holder;&nbsp_place_holder;1/ fsrf09.inp&nbsp_place_holder;&nbsp_place_holder;2/ fsrf44.inp&nbsp_place_holder;&nbsp_place_holder;2 /**flip/pinch **1.0   
This command will read 3 triangulated surface files, flip the normal from down
to up, and pinch layers less than 1.0 meter apart. When converted to a 3D
grid, this will be two elements thick in the z direction.

A surface is assigned the material value that occurs with it on the command
line. When the surfaces are filled with volumes, the nodes on the bottom
surface will detirmine the material of volume elements on and above that
surface. So nodes on fsrf575.inp and above will all have imt values of 1.
Nodes on fsrf09.inp and above will have imt equal to 2.

  
cmo create cmo_stack

**stack/layers/avs **/ fsrf575.inp&nbsp_place_holder;&nbsp_place_holder;1/&nbsp_place_holder; fsrf09.inp&nbsp_place_holder;&nbsp_place_holder;2/fsrf44.inp&nbsp_place_holder;&nbsp_place_holder;2/ **flip **/ **buffer ** 3.0 / **dpinch** 1.0 / **dmin** 3.0   
Same surfaces are used but buffer layers are added at 3 meters below and 3
meters above the unit interface fsrf09.inp. The units are pinched at anything
less than 1 meter and the mininum distance to next layer is 3 meters.

  
cmo create cmo_stack

**stack/layers/avs** / surf-12.inp&nbsp_place_holder;&nbsp_place_holder;1/ surf-5.inp&nbsp_place_holder;&nbsp_place_holder;2&nbsp_place_holder;3&nbsp_place_holder;/ surf5.inp&nbsp_place_holder;&nbsp_place_holder;3&nbsp_place_holder;&nbsp_place_holder;/ surf2_slope.inp&nbsp_place_holder;&nbsp_place_holder;4/ surf25.inp&nbsp_place_holder;&nbsp_place_holder;4&nbsp_place_holder;1&nbsp_place_holder;/ **truncate** 4 / **pinch** 0.   
**stack/fill/**cmohex/cmo_stack   
**hextotet//**cmotet/cmohex   
  
This command reads a list of quad surfaces and assigns material values 1
through 4. The first unit (between surf-12.inp and surf-5.inp) is
refined&nbsp_place_holder; by 3, so that 3 layers are added between these
surfaces. All materials will be 1 in this refined unit. The next two units,
material 2 and 3, will have no refinement layers added. The last unit is
refined once, with a layer between the surfaces surf2_slope.inp and
surf25.inp.

The fill option will fill the space between quad surfaces with hex elements.
This hex grid will have 4 units and 10 layers.

The hextotet command can be used to convert the hex grid to a tet grid. Note
that the second option to hextotet is defaulted. This allows hextotet to check
on the grid's mesh type and use the appropriate tet conversion. There will be
6 tet from each hex and there are 3 tets from each prism.

  
  
LINKS:

> [Simple Examples for stack](../stack_demo.html)

  
[Advanced Examples for stack](../stack_demo2.html)