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AFLR4 Release Notes

  • 10/31/23 RELEASE VERSION 11.5.10

    Enhancements/ Additions:

    • Added multi-zone capability for cases with multiple bodies and matching faces with curvature.

    Known Issues:

    • An invalid Tess object can be created after AFLR3 in cases with transparent surfaces that are connected together. To be corrected in the near future.


  • 06/26/23 RELEASE VERSION 11.5.6

    Enhancements/ Additions:

    • Added multi-zone capability for cases with multiple bodies and matching faces.

    Known Issues:

    • An invalid Tess object can be created after AFLR3 in cases with transparent surfaces that are connected together. To be corrected in the near future.


  • 04/20/23 RELEASE VERSION 11.4.5

    Enhancements/ Additions:

    • Initial implementation of multi-zone capability. To be completed in the near future.
    • Added option for configurations with a structural skin topology. Using either "-skin" or "skin_mode=1" option will activate skin mode. This option will ignore the specified Grid BC values and treat each surface as a transparent surface that can be topologically open.

    Bugs Fixed:

    • Fixed bug in conversion of trias to quads routine ug3_triaq.
    • Fixed bugs with parallel mode code.

    Known Issues:

    • An invalid Tess object can be created after AFLR3 in cases with transparent surfaces that are connected together. To be corrected in the near future.


  • 03/28/23 RELEASE VERSION 11.3.18

    Enhancements/ Additions:

    • Updated to EGADS v1.23.


  • 03/03/23 RELEASE VERSION 11.3.17

    Enhancements/ Additions:

    • Added AFLR4 input parameter for local quad-face combination/mesh generation flag.


  • 11/29/22 RELEASE VERSION 11.3.12

    Enhancements/ Additions:

    • Changed all sprintf calls to snprintf.


  • 11/18/22 RELEASE VERSION 11.3.8

    Enhancements/ Additions:

    • Added capability for quad dominant surface meshing. This capability can be invoked globally or by individual Faces using EGADS attributes or command line flags (see -quad).


  • 08/04/22 RELEASE VERSION 11.2.3

    Enhancements/ Additions:

    • Replaced all surface generation routines and updated internal structures for compatibility with anisotropic meshing and related libraries. The capability to actually generate an anisotropic surface mesh is in progress. The current routines will produce the same (or similar) mesh to previous versions of AFLR4.


  • 07/14/22 RELEASE VERSION 10.22.23

    Enhancements/ Additions:

    • Updated to EGADS v1.21.
    • Changes for compatibility with AFLR43.
    • Full capability for generating an EGADS tessellation with proper linkage to Faces and Edges from AFLR3 generated volume meshes along with complete integration with AFLR3.
    • Added capability in tess creation for singular points where three or more internal or periodic edges intersect.

    Bugs Fixed:

    • Fixed issue in tess creation with periodic edges.


  • 12/12/21 RELEASE VERSION 10.19.12

    Enhancements/ Additions:

    • Capability for generating an EGADS tessellation with proper linkage to Faces and Edges from AFLR3 generated volume meshes. Including multi-use edges and multi-use nodes.
    • Modified use of the global scale factor, sf_global.
    • Changes for interactive use.
    • Added internal variable for reference length, ref_len_, to store the input or computed reference length, ref_len.
    • Added an optional interactive test mode to the main program.


  • 09/14/21 RELEASE VERSION 10.17.7

    Enhancements/ Additions:

    • Update to EGADS 1.20.
    • Changes for saving edge grid connectivity and ID.


  • 07/02/21 RELEASE VERSION 10.16.1

    Enhancements/ Additions:

    • Added capability for EGADS Loops that contain duplicate Edges.
    • Modified EGADS tess creation and setting.


  • 05/25/21 RELEASE VERSION 10.15.9

    Enhancements/ Additions:

    • Update to EGADS 1.18.
    • Added capability for EGADS effective surface definitions.
    • Added input parameter flags -comp_ids and -comp_set_list to specify discrete or CAD effective/composite surface definitions.
    • Added capability to edit the input surface definition with surface definitions specified to either keep or remove.
    • Added input parameter flags -keep_ids and -rm_ids for editing the input surface definition.
    • Added input parameter flag mclosed to allow the input definition to be open. By default, a closed definition is required.
    • Restored API for aflr4_set_ext_cad_data to original form with only the CAD model as input.
    • Modified the process for creating and evaluating an EGADS Tess from the output surface mesh generated by AFLR4.
    • Removed check_tess argument from API for egads_aflr4_get_tess.


  • 02/11/21 RELEASE VERSION 10.13.7

    Enhancements/Additons:

    • Changes for compatibility with UG library routines and parameter initialization.
    • Added edge scale factor capability for EGADS CAD geometry definitions. The edge scale factor is set by the EGADS data file attribute AFLR4_Edge_Scale_Factor. If set for a given edge then the edge mesh spacing is scaled but the scale factor on the given edge.


  • 12/08/20 RELEASE VERSION 10.12.1

    Enhancements/Additons:

    • Internal changes for integration in interactive systems.
    • Added library aflr4_main for all main program related routines. To compile library aflr4_main along the version v1.86 dated 9 October 2020 or later is required.
    • All routines in src/aflr4/main have changed names to aflr4_main_
    • (some old, some new) and are included in library aflr4_main. See aflr4.c for current usage.
    • Changed name for number of TEST MODE overall repeat execution passes from Number_of_Calls to n_test_mode_overall_passes.
    • Minor revisions in documentation.


  • 09/22/20 RELEASE VERSION 10.9.5

    Enhancements/Additons:

    • Changes for compatibility with revised DGEOM library.
    • Revisions for interactive use in other systems.
    • Added automatic setting of the DGEOM data structure grid BC flag from the DGEOM definition structure values.
    • Separated out farfield add-on and auto BC setting options from initial geometry setup.


  • 08/23/20 RELEASE VERSION 10.8.7

    Enhancements/Additons:

    • Added parameters mier_ids and mier_list to control isolated edge refinement for individual surface definitions.
    • Added isolated edge refinement flag to DGEOM surface definition data structure.
    • Added EGADS attributes to control the isolated edge refinement. The EGADS attributes are AFLR4_mier (global isolated edge refinement flag) and AFLR4_Isolated_Edge_Refinement_Flag (individual surface isolated edge refinement flag).
    • Revised rank and description of some input parameters in aflr4_initialize_param.


  • 08/12/20 RELEASE VERSION 10.7.12

    Enhancements/Additons:

    • Added parameter Number_of_iCalls for testing interactive use.


  • 08/04/20 RELEASE VERSION 10.7.7

    Enhancements/Additons:

    • Modified setting of EGADS attributes.
    • Added setting of all attributes to the output EGADS geometry file.
    • Additional revisions to how surface definition data is stored and retrieved.
    • Changed parameter name of global surface mesh spacing scale factor from sf_all to sf_global. The name sf_all is still supported as an alternative name for sf_global.
    • Changed flag name of global edge refinement flag from -mer_all to -er_all. The flag -mer_all is no longer valid. Using the flag -er_all has the same effect, and still sets mer_all=1. The parameter name mer_all which is be set using mer_all=0 or mer_all=1 is still valid.
    • Added automatic setting of transparent grid BC if a surface has a free edge.
    • Added option to automatically set the farfield grid BC on the outermost closed body by setting the parameter option auto_set_ff_bc (which is on by default).
    • Added setting of all parameters used for automatic spacing to the output argument file, case_name.aflr4.arg. An additional argument file, case_name.inp.aflr4.arg is also output and contains only the arguments set via the command line. It is the same as the argument file output by previous versions of AFLR4.

    Bugs Fixed:

    • Corrected an issue determine edge-face and face neighbor maps with CAD geometry.
    • Corrected farfield spacing calculation.


  • 07/10/20 RELEASE VERSION 10.6.7

    Enhancements/Additons:

    • Changes for compatibility with revised DGEOM library.
    • Added setup of DGEOM data structure for global parameters within EGADS_AFLR4 library.
    • Revised substantially how surface definition data is stored and retrieved.
    • Revised main program.

    Bugs Fixed:

    • Corrected and simplified farfield spacing calculation.


  • 06/13/20 RELEASE VERSION 10.5.3

    Enhancements/Additons:

    • Modifications to improve surface spacing irregularity in cases with proximity spacing reduction.
    • Modified slightly farfield spacing calculation.
    • Reduced default farfield spacing growth factor from 1.5 to 1.3.
    • Created separate UVMAP library for uv mapping generation from AFLR4 and UG2 library routines.
    • Update to EGADS 1.18.


  • 05/14/20 RELEASE VERSION 10.4.4

    Enhancements/Additons:

    • Added Grid BC check.
    • Added modifications to insure that the minimum number of segments on a curve or loop set by min_nseg and min_nseg_loop is not limited my the minimum spacing set with min_scale and ref_len.
    • Added a new input parameter std_ids to set the Grid BC to standard surface (STD_UG3_GBC) for IDs specified.
    • Added the missing input parameter BC_IDs & Grid_BCs to set the grid BC to values specified for the surfaces specified.


  • 05/07/20 RELEASE VERSION 10.3.8

    Enhancements/Additons:

    • Modified u,v mapping used for scaling and singularity removal in CAD geometry definitions and eliminated internal parameters and limits. The primary process however did not change.


  • 04/23/20 RELEASE VERSION 10.2.16

    Enhancements/Additons:

    • Changed u,v mapping modification to use reduced scaling with CAD definitions that have a bounding curve that includes a discontinuity (physical edge length is zero). Note that in these cases the u,v mapping is transformed into a triangle shaped or diamond shaped mapping from the original square mapping.
    • Added capability to estimate the BL thickness based on Reynolds Number. A new AFLR4 parameter named Re_l was added to set Reynolds Number. A corresponding EGADS attribute named AFLR4_Re_l was also added.


  • 04/09/20 RELEASE VERSION 10.2.8

    Enhancements/Additons:

    • Modified process for determining farfield point spacing. The new process includes overall domain size, inner body size, reference length and field growth rate and results in improved determination of farfield spacing. The old parameter ff_nseg is no longer used or available. Instead, the primary user control on farfield spacing is a new parameter that controls the field spacing growth rate, ff_cdfr. The default value is 1.2 and the farfield spacing varies linearly when the value of ff_cdfr is changed.
    • Update to EGADS 1.17.
    • Added parallel mode capability using a fork/shared-memory strategy.
    • Modifications for surface based background mesh length scale interpolation.
    • Added growth to UV grid generation when edge refinement is active to reduce number of faces generated in approximation grid.
    • Changed parameter names for edge refinement. Previously the related parameters all were named msfe_all & sfe
    • and were labeled edge scale factor weight. They are now named mer_all
    • erw* and are labeled edge refinement weight.
    • Changed u,v mapping modification to not use scaling with CAD definitions that have a bounding curve that includes a discontinuity (physical edge length is zero). Note that in these cases the u,v mapping is transformed into a triangle shaped or diamond shaped mapping from the original square mapping.
    • Modified point insertion process for edges that are only attached to surface bounding curves.
    • Added capability to add overall AFLR4 parameters to the EGADS data as attributes attached to the model.
    • Added capability to add a rectangular or square box farfield geometry and add it to the EGADS data structure.
    • Added capability to write new EGADS data file with attributes that may be new and/or farfield box that may be added.

    Bugs Fixed:

    • Corrected an issue in proximity checking for surfaces which connect to themselves in xyz physical space.


  • 01/16/20 RELEASE VERSION 9.16.2

    Enhancements/Additons:

    • Added quad-tree based searching to surface based length scale evaluation.


  • 10/26/19 RELEASE VERSION 9.17.1

    Enhancements/Additons:

    • Modifications for surface based length scale background grid evaluation from volume based.


  • 08/16/19 RELEASE VERSION 9.16.1

    Enhancements/Additons:

    • Added a global surface mesh spacing factor parameter, sf_all. This parameter provides the capability to globally scale all surface mesh spacing.


  • 07/30/19 RELEASE VERSION 9.15.1

    Enhancements/Additons:

    • Added a lower and upper limit to uv values for evaluation of curvature on EGADS/OpenCASCADE surface definitions. This is to compensate for an issue in the underlying derivatives from OpenCASCADE that EGADS uses to calculate curvature. For some surface definitions there is a singularity in the derivative that causes erroneous curvature values at the uv boundaries of the surface definition. The input parameter uv_curv_lim provides a limit on how close to the actual boundary curvature can be evaluated (uv_curv_lim < uv < 1-uv_curv_lim). Discrete surface definitions are unchanged.


  • 07/09/19 RELEASE VERSION 9.14.11

    Enhancements/Additons:

    • Added new capability for generation and output of surface mesh quality using routine ug3_qchkb.
    • Changes for compatibility with revised lib DGEOM.
    • Modified initial edge grid generation process for improved efficiency.
    • The EGADS version of AFLR4 now uses EGADS Version 1.15 and OpenCASCADE Version 7.3.1.
    • Modified process to add and glue component surfaces within a composite surface definition. These modifications improve efficiency of the process significantly without altering the result.
    • Changed parameter check_tess_ordering to check_tess.
    • Added parameter cad_param_reset to reset all EGADS Attributes to default values for AFLR4.
    • Modified CAD surface definition mapping transformation for definitions with a singular point and an opposing near singular region (similar to a double singular football shaping mapping). The modified form improves the resulting surface mesh for these cases.

    Bugs Fixed:

    • Corrected evaluation issue that produced coordinates on curves that were offset from the actual surface definition.


  • 05/08/19 RELEASE VERSION 9.13.5

    Enhancements/Additons:

    • Added capability for high-order evaluation of discrete geometry.
    • Modified internal eigenvector analysis for curvature and high-order evaluation of discrete geometry.
    • Modified setting of default components for proximity.
    • Added input parameter options, cmp_ids and cmp_list, for setting of components for proximity based on surface ID.


  • 02/26/19 RELEASE VERSION 9.11.6

    Enhancements/Additons:

    • Added capability for gluing non-manifold connections with discrete geometry definitions.
    • Removed restriction that did not allow automatic scaling of surface edge mesh spacing based on discontinuity level between adjacent surfaces on both sides of the edge.
    • Improved uv-map generation for cases with interior curves.


  • 02/07/19 RELEASE VERSION 9.11.3

    Enhancements/Additons:

    • Added capability for gluing non-manifold connections with both discrete and CAD geometry definitions. Note that additional changes are required with discrete geometries.
    • Changed all face neighbor map creation calls to the full 3D routine that allows for non-manifold multiply connected surfaces.


  • 01/28/19 RELEASE VERSION 9.10.11

    Enhancements/Additons:

    • Changes for compatibility with modified EGADS_AFLR4 that now uses EGADS bodies as the data source instead of an EGADS model.


  • 12/11/18 RELEASE VERSION 9.9.11

    Enhancements/Additons:

    • Added edge mesh spacing scale factor for each surface. This allows the spacing on edges of a given surface to be modified based on the level of discontinuity between neighboring surfaces that share an edge.
    • Added global edge mesh spacing scale factor option.
    • Made edge mesh spacing scale modified spacing based on log interpolation.
    • Changes for compatibility with EGADS_AFLR4 LIB.


  • 11/10/18 RELEASE VERSION 9.8.13

    Enhancements/Additons:

    • Changes for compatibility with new surf_auto and surf_auto_cpp libs (which include all of previous dcurv, egen_auto and surfgen libs).
    • Changes for compatibility with new C-code API of surf_auto_cpp and ug_cpp libs.


  • 11/04/18 RELEASE VERSION 9.8.10

    Enhancements/Additons:

    • Added check if EGADS_INCLUDE_DIR is set and if it includes the EGADS system include files then that directory is used instead of egads_include. NOTE: This check is included in both egads_aflr4.compile_lib and aflr4/aflr4.compile.
    • Added routine aflr4_cad_geom_file_cleanup to free all CAD geometry file related array space and close any open files.
    • Changes for compatibility with revised DCURV, EGEN_AUTO, and SURFGEN libs.


  • 10/26/18 RELEASE VERSION 9.8.8

    Enhancements/Additons:

    • Added capability to specify a mesh size scaling factor on each surface definition.
    • Added option to create an add-on farfield using add_ff_geom.


  • 10/18/18 RELEASE VERSION 9.7.4

    Enhancements/Additons:

    • Added removal of BL intersecting surfaces within the back-ground grid to improve proximity checking.
    • Added check for surfaces with projected uv-mapping set (planar surfaces) that do not have far-field or BL-intersecting grid BCs. If found the ug-mapping is set back to free-boundary uv-mapping. This process is activated only during proximity checking.


  • 10/05/18 RELEASE VERSION 9.6.7

    Enhancements/Additons:

    • Added support of multiple-bodies within EGADS models.
    • Improved handling of degenerate CAD edges.
    • Added transparent surface capability.

    Bugs Fixed:

    • Fixed a potential surface spacing value mismatch.


  • 09/25/18 RELEASE VERSION 9.5.6

    Enhancements/Additons:

    • Added auto-generation of edge and surface grids with curvature dependent spacing.


  • 08/15/18 RELEASE VERSION 9.3.3

    Enhancements/Additons:

    • Added auto-generation of edge and surface grids.
    • Modified use of growth rate to prevent limiting in compression.


  • 12/06/17 RELEASE VERSION 8.19.1

    Enhancements/Additons:

    • Added general process for setting length scale data using an interpolation process with a background grid (or similar). This process now includes the boundary edge grid data.


  • 08/07/17 RELEASE VERSION 8.17.51

    Enhancements/Additons:

    • Added external/extra CAD geometry data to the geometry definition data structure for passing to external CAD evaluation routines. Note that the API for all external `functions defined by the aflr4_register_cad_geom_
    • functions were modified to accommodate this change.


  • 06/13/17 RELEASE VERSION 8.16.47

    Enhancements/Additons:

    • Changes for compatibility with 64-bit integers.


  • 12/17/16 RELEASE VERSION 8.15.42

    Enhancements/Additons:

    • Changes for compatibility with revised libraries.


  • 07/31/16 RELEASE VERSION 8.15.34

    Enhancements/Additons:

    • Added an option, -disp, to create and output a glue-only mesh that is reduced for graphical display. routine aflr4_get_def.
    • Modified the default boundary edge spacing set in EGADS.


  • 05/18/16 RELEASE VERSION 8.13.31

    Enhancements/Additons:

    • Added a no quad face option to routine aflr4_get_def.

    Bugs Fixed:

    • Corrected an issue writing final surface grid file.


  • 04/04/16 RELEASE VERSION 8.12.28

    Enhancements/Additons:

    • Changes for compatibility with new version of egen.
    • Added normal spacing argument for use with AFLR3.
    • Changes for compatibility with new version of AFLR2C.
    • Added compatibility with AFLR2C metric normal spacing specification that is compatible with AFLR3 metric BL blending.
    • Combined AFLR4 Lib and AFLR4_API Lib. AFLR4_API Lib is no longer separate or used.


  • 07/30/15 RELEASE VERSION 8.2.4

    Enhancements/Additons:

    • Added integration with the Engineering Geometry Aircraft Design System (EGADS) from MIT and Open CASCADE from Open CASCADE S.A.S. for CAD functionality. Both are licensed under The GNU Lesser General Public License, version 2.1 and are freely available. See aflr4_cad_geom.c for more information.
    • Added capability to import a full CAD model compatible with the above and generate a surface mesh suitable for AFLR3 volume grid generation. With the current system the AFLR4 executable is now suitable as is for complete surface generation.
    • Modified calling sequence and routines library aflr4_api. Most APIs have changed and any code that integrates AFLR4 will require modification to be compatible with the current API.
    • See aflr4 -h or aflr4 -help for information on command line options.


  • 03/31/15 RELEASE VERSION 7.3.29

    Enhancements/Additons:

    • Reduced mapping generation output slightly.
    • Modified internal API for surface search (ug3_srchbf) to allow for a two-pass algorithm that uses a large tolerance on the second pass to find locations that are off the surface and near a surface node.


  • 07/06/14 RELEASE VERSION 7.2.18

    Enhancements/Additons:

    • Updated API for initialization of external sizing function in DFTR3 library. This required an internal API change for routine g4fgen. The external API for all aflr4_
    • routines is unchanged.


  • 06/26/14 RELEASE VERSION 7.1.18

    Enhancements/Additons:

    • Change include for REC3_API_LIB to REC3_LIB.


  • 06/26/14 RELEASE VERSION 7.1.17

    Enhancements/Additons:

    • Updated API for initialization of external sizing function in DFTR3 library. This required an internal API change for routine g4fgen. The external API for all aflr4_
    • routines is unchanged.


  • 06/03/14 RELEASE VERSION 7.1.15

    Enhancements/Additons:

    • Convert to new ug parameter structure scheme and eliminate use of Error_Message.


  • 10/20/13 RELEASE VERSION 6.10.27

    Enhancements/Additons:

    • Updated character string declarations.


  • 01/30/13 RELEASE VERSION 6.10.24

    Enhancements/Additons:

    • Updated API for changes related to mappings based on projecting to a plane.


  • 01/11/13 RELEASE VERSION 6.11.24

    Enhancements/Additons:

    • Updated CMake files.