AFLR3 Tutorial – Isotropic Cases
The following tutorial example cases demonstrate various capabilities within AFLR3 for controlling the point spacing with an isotropic grid. Some of these capabilities are also useful in controlling the point spacing in the isotropic grid region with a BL/SL/SNS grid. SolidMesh is used in the following sections to run the cases. A basic proficiency with SolidMesh is assumed. The data files for these cases are minim.SM.gz and minim2.SM.gz (right click to save/download each file). Alternatively, each of these cases can be run from a terminal window using the aflr3 script command. The surface grid files for these cases are minim_iso_1.surf.gz, minim_iso_2_1.surf.gz, minim_iso_2_2.surf.gz, minim_iso_2_3.surf.gz, and minim2_iso_3.surf.gz.
The minim and minim2 cases are two versions of a missile like configuration. The missile itself has three zero thickness fins (that are off by default in the minim2 case) and an internal nozzle and motor exit. In the minim case there is a large far-field, near-field embedded surface to control near-body spacing, and an embedded surface to control plume spacing. The minim case is shown below with the far-field and without the far-field.
In the minim2 case the far-field is very close and the plume is treated as a solid surface. The minim2 case is shown below.
1. ISOTROPIC GRID - INTERPOLATED AND SPECIFIED GROWTH
1.1.Default interpolated growth isotropic grid
Alternative Terminal Window AFLR3 Script Command
aflr3 minim_iso_1.surf.gz –w
- Terminal Window
o run SolidMesh for case minim
sm –case minim.SM.gz
- SGen Panel
o deactivate surface groups for near-field, plume, and fins (these groups are for the full viscous grid case)
o generate surface grid
- VGen Panel
o set isotropic grid type
o generate volume grid
- Viz Panel
o read-in volume grid
o generate X-Y cutting plane
1.2.Normal growth with moderate growth rate
Alternative Terminal Window AFLR3 Script Command
aflr3 minim_iso_1.surf.gz –grow1 –w
- SGen Panel
o generate surface grid
- VGen Panel
o set moderate growth
o generate volume grid
- Viz Panel
o read-in volume grid
o generate X-Y cutting plane
1.3.Normal growth with high growth rate
Alternative Terminal Window AFLR3 Script Command
aflr3 minim_iso_1.surf.gz -grow2 –w
- SGen Panel
o generate surface grid
- VGen Panel
o set high growth
o generate volume grid
- Viz Panel
o read-in volume grid
o generate X-Y cutting plane
2. ISOTROPIC GRID - SPACING CONTROL WITH SOURCE SURFACE
2.1.Full source surface
Alternative Terminal Window AFLR3 Script Command
aflr3 minim_iso_2_1.surf.gz –w
- Terminal Window
o run SolidMesh for case minim
sm –case minim.SM.gz
- SGen Panel
o deactivate surface groups for plume and fins (these groups are for the full viscous grid case)
o activate near-field surface group (this is the source surface)
o generate surface grid
- VGen Panel
o set isotropic grid type
o generate volume grid
- SGen Panel
o deactivate near-field surface group (avoid current graphics issue when volume grid is displayed later)
o generate surface grid (avoid current graphics issue when volume grid is displayed later)
- Viz Panel
o read-in volume grid
o generate X-Y cutting plane
2.2.Open half source surface
Alternative Terminal Window AFLR3 Script Command
aflr3 minim_iso_2_2.surf.gz –w
- SGen Panel
o activate small-far-field surface group
- VGen Panel
o select small-far-field surface group
o set BC to source on small-far-field surface group
- SGen Panel
o generate surface grid
- VGen Panel
o generate volume grid
- SGen Panel
o deactivate small-far-field surface group (avoid current graphics issue when volume grid is displayed later)
o generate surface grid (avoid current graphics issue when volume grid is displayed later)
o generate surface grid
- Viz Panel
o read-in volume grid
o generate X-Y cutting plane
.
2.3.Fins with anisotropic spacing
Alternative Terminal Window AFLR3 Script Command
aflr3 minim_iso_2_3.surf.gz –w
- VGen Panel
o activate fins surface group
o select fins surface group
o set BC to source for fins surface group
- SGen Panel
o generate surface grid
- VGen Panel
o generate volume grid
- SGen Panel
o deactivate fins surface group (avoid current graphics issue when volume grid is displayed later)
o generate surface grid (avoid current graphics issue when volume grid is displayed later)
o generate surface grid
- Viz Panel
o read-in volume grid
o generate X-Z cutting plane at Y=70
2.4.Fins with anisotropic spacing
Alternative Terminal Window AFLR3 Script Command
aflr3 minim_iso_2_3.surf.gz -trsrc -trds 0.1 –w
- Terminal Window
o re-generate volume grid from script with anisotropic source transformation using a normal spacing of 0.1 adjacent to fins
./minim.script -trsrc -trds 0.1
- Viz Panel
o read-in volume grid
o generate X-Z cutting plane at Y=70
o generate Y-Z cutting plane
3. ISOTROPIC GRID - SPACING CONTROL WITH MAXIMUM ELEMENT SIZE LIMIT OR ELEMENT SIZE MULTIPLIER
3.1.Default isotropic grid
Alternative Terminal Window AFLR3 Script Command
aflr3 minim2-3.surf.gz –w
- Terminal Window
o run SolidMesh for case minim2
sm –case minim2.SM.gz
- SGen Panel
o deactivate surface group for fins
o generate surface grid
- VGen Panel
o set isotropic grid type
o generate volume grid
- Viz Panel
o read-in volume grid
o generate X-Y cutting plane
3.2.Limit maximum element size
Alternative Terminal Window AFLR3 Script Command
aflr3 minim_iso_3.surf.gz -dfmax 2 –w
- SGen Panel
o generate surface grid
- VGen Panel
o select specify max-element size limit toggle
o set max-element size limit to 2
o generate volume grid
- Viz Panel
o read-in volume grid
o generate X-Y cutting plane
3.3.Lower maximum element size limit
Alternative Terminal Window AFLR3 Script Command
aflr3 minim_iso_3.surf.gz -dfmax 1 –w
- SGen Panel
o generate surface grid
- VGen Panel
o set max-element size limit to 1
o generate volume grid
o un-select specify and select none for max-element size limit toggle
- Viz Panel
o read-in volume grid
o generate X-Y cutting plane
3.4.Lower element size multiplier
Alternative Terminal Window AFLR3 Script Command
aflr3 minim_iso_3.surf.gz -cdf 0.8 –w
- SGen Panel
o generate surface grid
- VOpt Panel
o scroll to parameter named cdf
o set cdf to 0.8 (enter return in field to set)
- VGen Panel
o generate volume grid
- VOpt Panel
o scroll to parameter named cdf
o select reset
- Viz Panel
o read-in volume grid
o generate X-Y cutting plane
3.5.Increase element size multiplier and growth rate
Alternative Terminal Window AFLR3 Script Command
aflr3 minim_iso_3.surf.gz -cdf 2 cdfr=2 –w
- SGen Panel
o generate surface grid
- VOpt Panel
o scroll to parameter named cdf
o set cdf to 2 (enter return in field to set)
o scroll to parameter named cdfr
o set cdfr to 2 (enter return in field to set)
- VGen Panel
o generate volume grid
- Viz Panel
o read-in volume grid
o generate X-Y cutting plane
