The following list of attributes are available to guide the mesh generation with the AFLR4 AIM.

• capsMeshLength [Required BODY attribute] This numeric BODY attribute sets the AFLR4 ref_len input. capsMeshLength should be a a positive value representative of a characteristic length of the geometry, e.g. the MAC of a wing or diameter of a fuselage. The AIM input Mesh_Length_Factor may be used to apply a global scaling to increase or decrease the mesh resolution.
  

From the AFLR4 documentation:

ref_len:
Reference length for components/bodies in grid units. Reference length should
be set to a physically relevant characteristic length for the configuration
such as wing chord length or pipe diameter. If ref_len = 0 then it will be set
to the bounding box for the largest component/body of interest.
The parameters ref_len, max_scale, ideal_min_scale and abs_min_scale are all used to
set spacing values on all component/body surfaces (those that are not on the
farfield or symmetry plane-if any).

max_spacing = max_scale * ref_len
min_spacing = ideal_min_scale * ref_len
abs_min_spacing = abs_min_scale * ref_len

• AFLR_GBC [Optional FACE attribute: Default STD_UG3_GBC] This string FACE attribute informs AFLR4 what BC treatment should be employed for each geometric FACE. The BC defaults to the string STD_UG3_GBC if none is specified.

Predefined AFLR Grid BC string values are:

Within AFLR4 the grid BC determines how automatic spacing is applied. Their are four basic Grid BC types that are each treated differently.

1. Faces/surfaces that are part of the farfield should be given a FARFIELD_UG3_GBC Grid BC. Farfield faces/surfaces are given a uniform spacing independent of other faces/surfaces with different Grid BCs.
   
   
2. Faces/surfaces that represent standard solid surfaces should be given either a STD_UG3_GBC or -STD_UG3_GBC (BL generating) Grid BC. Standard surfaces are given a curvature dependent spacing that may be modified by proximity checking.
   
   
3. Faces/surfaces that intersect a BL region should be given either a BL_INT_UG3_GBC (standard boundary surface) or TRANSP_BL_INT_UG3_GBC (embedded/ transparent surface with volume mesh on both sides) Grid BC. A common example for the BL_INT_UG3_GBC Grid BC is a symmetry plane. Faces/surfaces set as BL intersecting surfaces are excluded from auto spacing calculations within AFLR4 and use edge spacing derived from their neighbors.
   
   
4. Surfaces set as transparent surfaces will have a volume mesh on both sides. They can have free edges and can have non-manifold connections to standard solid surfaces and/or BL intersecting surfaces. Vertices in the final surface mesh are not duplicated at non-manifold connections. Transparent surfaces use curvature driven surface spacing as used on standard solid surfaces. However, at non-manifold connections with standard solid surfaces they inherit the surface spacing set on the solid surface they are attached to. They are also excluded from proximity checking. Typical examples of transparent surfaces include wake sheets or multi-material interface surfaces.
   
   

• AFLR4_Cmp_ID [Optional FACE attribute]
  EGADS attribute AFLR4_Cmp_ID represents the component identifier for a given face/surface. Component IDs are used for proximity checking. Proximity is only checked between different components. A component is one or more CAD surfaces that represent a component of the full configuration that should be treated individually. For example, a wing-body-strut-nacelle configuration could be considered as four components with wing surfaces set to component 1, body surfaces set to component 2, nacelle surfaces set to 3, and store surfaces set to 4. If each component is a topologically closed surface/body then there is no need to set components. If component IDS are not specified then component identifiers are set for each body defined in the EGADS model or topologically closed surfaces/bodies of the overall configuration. Proximity checking is disabled if there is only one component/body defined. Note that proximity checking only applies to standard surfaces. Component identifiers are set by one of three methods, chosen in the following order.
  
  

1. If defined by EGADS attribute AFLR4_Cmp_ID then attribute sets component identifier.
   
2. Else, if multiple bodies are defined in the EGADS model then bodies index is used to set component identifier.
   
3. Else, component identifiers are set an index based on topologically closed surfaces/bodies of the overall configuration.
   
   

• AFLR4_Isolated_Edge_Refinement_Flag [Optional FACE attribute: Integer Range 0 to 2]
  Isolated edge refinement flag. If Flag = 0 then do not refine isolated interior edges. If Flag = 1 then refine isolated interior edges if the surface has local curvature (as defined using cier). If Flag = 2 then refine all isolated interior edges. An isolated interior edges is connected only to boundary nodes. Isolated edges are refined by placing a new node in the middle of of the edge. Note that if not set then the isolated edge refinement flag is set to the global value AFLR4_mier.
  
• AFLR4_Edge_Refinement_Weight [Optional FACE attribute: Default 0.0, Range 0 to 1]
  EGADS attribute AFLR4_Edge_Refinement_Weight represents the edge mesh spacing scale factor weight for a given face/surface. Edge mesh spacing can be scaled on a given face/surface based on the discontinuity level between adjacent faces/surfaces on both sides of the edge. The edge mesh spacing scale factor weight set with AFLR4_Edge_Refinement_Weight is used as an interpolation weight between the unmodified spacing and the modified spacing. A value of one applies the maximum modification and a value of zero applies no change in edge spacing. Note that no modification is done to edges that belong to farfield or BL intersecting face/surface.
  
• AFLR4_Scale_Factor [Optional FACE or EDGE attribute: Default 1.0]
  EGADS attribute AFLR4_Scale_Factor represents the AFLR4 mesh spacing scale factor for a given face/edge. Curvature dependent spacing can be scaled on the face/edge by the value of the scale factor set with AFLR4_Scale_Factor.
  
  
• AFLR4_quad_local [Optional FACE attribute: Default 0.0]
  Local quad-face combination flag.
  If AFLR4_quad_local is set to 0, then do not combine tria-faces to form quad-faces.
  If AFLR4_quad_local is set to 1, then combine tria-faces to form quad-faces.
  This option also locally selects advancing-point point placement rather than the default advancing-front point placement. Note that if not set then the local quad-face combination flag is set to the global quad-face combination flag AFLR4_quad.