Phasta Meshing

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Creating the Boundary Layer Attribute File

• To begin, we need a geometry model. It can be created using commercial softwares such as SolidWorks or NX and saved as *.x_t
• Create a new directory, which will contain the new geometric model and boundary layer attribute file (BLattr.inp). Make a link to the geometric model:

  ln -s "model_name.x_t" geom.xmt_txt

Now copy whichever BLattr.inp file you wish to start from to your working directory.

• Each face of the geometric model needs specific mesh and boundary layer characteristics. This is the purpose of BLattr.inp. Open it by typing:

  vim BLattr.inp

A vim command cheat sheet can be found at http://www.tuxfiles.org/linuxhelp/vimcheat.html

• To create attributes for each model entity, two lines in the following format are being used.

 <entity dimension> <entity tag> <size type> <attribute type> <extra> 
 <value or expression for mesh size on this entity>

• Note that a blank line between these two lines is not allowed.
• The parameters in the first line, respectively are:

- Entity dimension:          This will be 2 if the BL is being specified on a face
- Entity tag:                     You can find the entity tag using simapps
- Size type on entity:       1 for absolute mesh size and 2 for relative mesh size
- Attribute type on entity:  
                             0 just imposes the size on entity. <extra> field is NULL
                             1 for entity with boundary layers. <extra> field is explained below.
                             2 for periodic entity: In this case, <extra> field is followed with slave entity tag
                             3 for refinement source. Specify entity dimension as -1 in this case. <extra> field is explained below.

For Boundary layer:

   the <extra> field consists of (a) faceSide/useDir (BL orientation), (b) numEndEnts (==0, layers with fixed heigths), (c) firstLayerHeight, (d) totalHeight, 

(e) nLayers, (f) blMixed, (g) blBlends, (h) blPropagate and (i) edgeBLFaceTag (only if 2D BL on edge)

• You need the BLMesher code which can be found at:

  /users/mrasquin/develop/Meshing/bin/x86_64_linux/BLMesher