CAVS / Capabilities / Software and Codes / CFD Software Forum / CFD Software Documentation / AFLR43 / Example Cases Tutorial

AFLR43 Example Cases Tutorial

Data files for a few AFLR43 sample cases are provided. Package archives with all of the example cases are provided in aflr43-examples.tar.gz (tar-gzip archive for Linux/MacOSX) and aflr43-examples.zip (zip archive for Windows). Copy the package archive files and unpackage them in a location of your choosing to run the example cases. All cases require minimal resources. AFLR43 takes the provided input geometry definition and automatically generates a surface and volume mesh with spacings based on surface type, surface curvature and proximity of multiple components. AFLR43 as provided can work with a discrete geometry definition or an EGADS CAD geometry definition.

AFLR43 command line options include both parameter options for AFLR4 and AFLR3 components.

aflr43 [aflr4_param_options] [-AFLR3 aflr3_param_options]

The -AFLR3 flag is required to separate the AFLR4 and AFLR3 options. In command line mode the AFLR4 input geometry definition file and the AFLR3 output mesh file names must be specified. If the input geometry definition is an EGADS geometry definition Model, then a tessellation of the AFLR3 output mesh is included in the output EGADS geometry definition Model.

See the AFLR43 documentation for information on all available options and usage. Alternatively, you can view text-based documentation at the command line with the following command.

aflr43 -h or aflr43 -help

See the AFLR4 documentation and AFLR3 documentation for related information.

An overview of AFLR43 example cases is provided in the following along with run parameters. All these cases use EGADS geometry definition Models and are also included with AFLR4 sample cases. One uses Effective Bodies to aggregate multiple Faces as Effective Faces. The other two cases use Face Topology that have Edges that are internal to the given Face. AFLR3 will preserve these internal Edges, which is particularly important when those Faces intersect BL regions and are re-meshed within AFLR3. For each case the command line for AFLR43 along with equivalent for running AFLR4 and AFLR3 separately. Either approach results in the exact same final output, and one should use whichever is works with their overall process. Note that AFLR3 will only produce an EGADS geometry definition Model with an output mesh tessellation if the surface mesh was generated by AFLR4. Also, to run AFLR4 and AFLR3 separately you must use the aflr3t executable (not the base aflr3 executable). In addition, note that in the separate process only the SURF and UGRID file types retain the grid BCs. If another output file type is used (i.e., MESH) the aflr3t command line the same grid BC parameters as for aflr4 must be added.

Bent Pipe with Effective Topology

A simple bent pipe with inflow and output ends. The underlying Model topology with multiple Faces that have connectivity that produces artifacts in the surface mesh. Reference length is set equal to the pipe diameter.

aflr43 -i bent_pipe_eff.egads -log -bl_ids 1,2 -int_ids 3,4
-AFLR3 -o a43_bent_pipe_eff.meshb -bl -blds 0.01

aflr4 -i bent_pipe_eff.egads -log -bl_ids 1,2 -int_ids 3,4 -o a4_bent_pipe_eff.surf
aflr3t -i a4_bent_pipe_eff.surf -o a3_bent_pipe_eff.meshb -log -bl -blds 0.01

Bent Pipe
Bent Pipe

Piston

A simple piston with inflow and outflow passages on both ends and the side holes. Reference length is set equal to the minimum bounding box size of the piston. Both holes and the piston surfaces have internal edges that are preserved in the output volume mesh.

aflr43 -i piston.egads -log -bl_ids 1,6,7 -bl_ints 2,3,4,5
-AFLR3 -o a43_piston.meshb -bl -blds 0.1

aflr4 -i piston.egads -log -bl_ids 1,6,7 -bl_ints 2,3,4,5 - o a4_piston.surf
aflr3t -i a4_piston.surf -o a3_piston.meshb -log -bl -blds 0.1

Piston
Piston

Box with Cylinder

A simple box with a cylinder intersecting the inflow/outflow top and bottom. Reference length is set equal to cylinder diameter. The top and bottom surfaces have internal edges that are preserved in the output volume mesh. Note that body 1 (a farfield box) is ignored. Both box and cylinder surfaces have internal edges that are preserved in the output volume mesh.

aflr43 -i mel.egads -log -std_ids 1,2,4,6,7 -bl_ids 8,9 -int_ids 3,5 -keep_bodies 0, -ref_len 0.1
-AFLR3 -o a43_mel.meshb -bl -blds 0.01

aflr4 -i mel.egads -log -std_ids 1,2,4,6,7 -bl_ids 8,9 -int_ids 3,5 -keep_bodies 0, -ref_len 0.1
-o a4_mel.surf
aflr3t -i a4_mel.surf -o a3_mel.meshb -log -bl -blds 0.01

Box with Cylinder
Box with Cylinder