ENH: yPlus: add option to disable wall function contributions (#1773) (!381) · Merge Requests · Development / openfoam

ENH: yPlus: add option to disable wall function contributions (#1773)

Summary

See the self-explanatory commit messages.

Resolved bugs (If applicable)

#1773

Details of new models (If applicable)

Small test cases: GL1773-pre-fix.zip vs GL1773-post-fix

Test-case characteristics:

One-dimensional smooth-wall plane channel flow, ReTau=5200
Number of cells = 20
nu = 0.000192827 [m2/s]
The case was designed to produce => -1*sqrt(mag(wallShearStress)) = 1
The y1+ set (expected) = {0.05, 0.5, 1, 5, 10, 20, 30, 50, 100, ~~1000~~}
kOmegaSST/SpalartAllmaras, simpleFoam

Main field of interest:

mag(wallShearStress) function object returns ~ 1 for all test cases, therefore the expected y1+
yPlus function object (min) results for lowerWall rounded up to 2 decimals:

y1+ = 0.05:

Wall function	Pre-fix yPlus	Post-fix yPlus (when `useWallFunction=false`)
nutUWallFunction	0.12	0.05
nutkWallFunction	0.00025	0.05
nutUSpaldingWallFunction	0.05	0.05
nutUBlendedWallFunction	0.05	0.05
nutLowReWallFunction	0.05	0.05

y1+ = 0.5:

Wall function	Pre-fix yPlus	Post-fix yPlus (when `useWallFunction=false`)
nutUWallFunction	0.18	0.50
nutkWallFunction	0.025	0.50
nutUSpaldingWallFunction	0.50	0.50
nutUBlendedWallFunction	0.50	0.50

y1+ = 1:

Wall function	Pre-fix yPlus	Post-fix yPlus (when `useWallFunction=false`)
nutUWallFunction	0.34	1.00
nutkWallFunction	0.1	1.00
nutUSpaldingWallFunction	1.00	1.00
nutUBlendedWallFunction	1.00	1.00

y1+ = 5:

Wall function	Pre-fix yPlus	Post-fix yPlus (when `useWallFunction=false`)
nutUWallFunction	3.02	5.00
nutkWallFunction	2.75	5.00
nutUSpaldingWallFunction	5.00	5.00
nutUBlendedWallFunction	5.00	5.00

y1+ = 10:

Wall function	Pre-fix yPlus	Post-fix yPlus (when `useWallFunction=false`)
nutUWallFunction	9.12	10.00
nutkWallFunction	8.31	10.00
nutUSpaldingWallFunction	10.00	10.00
nutUBlendedWallFunction	10.00	10.00

y1+ = 20:

Wall function	Pre-fix yPlus	Post-fix yPlus (when `useWallFunction=false`)
nutUWallFunction	20.00	20.02
nutkWallFunction	19.30	20.01
nutUSpaldingWallFunction	20.00	20.00
nutUBlendedWallFunction	20.00	20.01

y1+ = 30:

Wall function	Pre-fix yPlus	Post-fix yPlus (when `useWallFunction=false`)
nutUWallFunction	30.09	30.09
nutkWallFunction	29.91	30.12
nutUSpaldingWallFunction	30.08	30.08
nutUBlendedWallFunction	30.09	30.09

y1+ = 50:

Wall function	Pre-fix yPlus	Post-fix yPlus (when `useWallFunction=false`)
nutUWallFunction	50.16	50.16
nutkWallFunction	50.51	50.19
nutUSpaldingWallFunction	50.17	50.17
nutUBlendedWallFunction	50.16	50.16

y1+ = 100:

Wall function	Pre-fix yPlus	Post-fix yPlus (when `useWallFunction=false`)
nutUWallFunction	100.01	100.01
nutkWallFunction	100.96	100.01
nutUSpaldingWallFunction	100.01	100.01
nutUBlendedWallFunction	100.01	100.01

Risks

Compiled with Gcc-7.4.1/Clang-9.0, DPInt32Opt
No regression issue: 1-pre-fix-yPlus.zip vs 2-post-fix-yPlus.zip (Test: incompressible/pisoFoam/RAS/cavity)
No changes in the default behaviour.
- User can now select the new behaviour by useWallFunction=false which is by default true.

### Summary

See the self-explanatory commit messages.

### Resolved bugs (If applicable)

#1773

### Details of new models (If applicable)

Small test cases: [GL1773-pre-fix.zip](/uploads/55a0e0a9f20b72222d7f1710a1f742d9/GL1773-pre-fix.zip) vs [GL1773-post-fix](/uploads/6e82b41f337cf0b251280bffb0eb9b9d/GL1773-post-fix.zip)

Test-case characteristics:

* One-dimensional smooth-wall plane channel flow, ReTau=5200
* Number of cells = 20
* nu = 0.000192827 \[m2/s\]
* The case was designed to produce => -1\*sqrt(mag(wallShearStress)) = 1
* The y1+ set (expected) = {0.05, 0.5, 1, 5, 10, 20, 30, 50, 100, ~~1000~~}
* kOmegaSST/SpalartAllmaras, simpleFoam

Main field of interest:

* mag(wallShearStress) function object returns \~ 1 for all test cases, therefore the expected y1+
* yPlus function object (min) results for `lowerWall` rounded up to 2 decimals:

### y1+ = 0.05:

| Wall function | Pre-fix yPlus | Post-fix yPlus (when `useWallFunction=false`) |
| ---      |  ------  |---------:|
| nutUWallFunction   | **0.12**   | 0.05   |
| nutkWallFunction   | **0.00025**   | 0.05   |
| nutUSpaldingWallFunction   | 0.05   | 0.05   |
| nutUBlendedWallFunction   | 0.05   | 0.05   |
| nutLowReWallFunction   | 0.05   | 0.05   |

### y1+ = 0.5:

| Wall function | Pre-fix yPlus | Post-fix yPlus (when `useWallFunction=false`) |
| ---      |  ------  |---------:|
| nutUWallFunction   |  **0.18**  | 0.50   |
| nutkWallFunction   |  **0.025**  |  0.50  |
| nutUSpaldingWallFunction   | 0.50   | 0.50   |
| nutUBlendedWallFunction   | 0.50   |  0.50  |

### y1+ = 1:

| Wall function | Pre-fix yPlus | Post-fix yPlus (when `useWallFunction=false`) |
| ---      |  ------  |---------:|
| nutUWallFunction   | **0.34**   | 1.00   |
| nutkWallFunction   |  **0.1**  |   1.00 |
| nutUSpaldingWallFunction   | 1.00   |  1.00  |
| nutUBlendedWallFunction   | 1.00   |    1.00 |

### y1+ = 5:

| Wall function | Pre-fix yPlus | Post-fix yPlus (when `useWallFunction=false`) |
| ---      |  ------  |---------:|
| nutUWallFunction   |  **3.02**  | 5.00   |
| nutkWallFunction   |  **2.75**  |  5.00  |
| nutUSpaldingWallFunction   | 5.00   |  5.00  |
| nutUBlendedWallFunction   | 5.00   |  5.00  |

### y1+ = 10:

| Wall function | Pre-fix yPlus | Post-fix yPlus (when `useWallFunction=false`) |
| ---      |  ------  |---------:|
| nutUWallFunction   |  **9.12**  |  10.00  |
| nutkWallFunction   |  **8.31**  |  10.00  |
| nutUSpaldingWallFunction   | 10.00   |  10.00  |
| nutUBlendedWallFunction   | 10.00   |  10.00  |

### y1+ = 20:

| Wall function | Pre-fix yPlus | Post-fix yPlus (when `useWallFunction=false`) |
| ---      |  ------  |---------:|
| nutUWallFunction   | 20.00   |  20.02  |
| nutkWallFunction   |  **19.30**  |  20.01  |
| nutUSpaldingWallFunction   |  20.00  | 20.00   |
| nutUBlendedWallFunction   | 20.00   | 20.01   |

### y1+ = 30:

| Wall function | Pre-fix yPlus | Post-fix yPlus (when `useWallFunction=false`) |
| ---      |  ------  |---------:|
| nutUWallFunction   |  30.09  |  30.09  |
| nutkWallFunction   |  29.91  | 30.12   |
| nutUSpaldingWallFunction   |  30.08  |  30.08  |
| nutUBlendedWallFunction   |  30.09  |  30.09  |

### y1+ = 50:

| Wall function | Pre-fix yPlus | Post-fix yPlus (when `useWallFunction=false`) |
| ---      |  ------  |---------:|
| nutUWallFunction   |  50.16  |  50.16  |
| nutkWallFunction   |  50.51  | 50.19   |
| nutUSpaldingWallFunction   | 50.17   |  50.17  |
| nutUBlendedWallFunction   | 50.16   |  50.16  |

### y1+ = 100:

| Wall function | Pre-fix yPlus | Post-fix yPlus (when `useWallFunction=false`) |
| ---      |  ------  |---------:|
| nutUWallFunction   |  100.01  | 100.01   |
| nutkWallFunction   |  100.96  |  100.01  |
| nutUSpaldingWallFunction   |  100.01  | 100.01   |
| nutUBlendedWallFunction   |  100.01  | 100.01   |

### Risks

- Compiled with Gcc-7.4.1/Clang-9.0, DPInt32Opt
- No regression issue: [1-pre-fix-yPlus.zip](/uploads/213187624c831a9322790f83da09bd95/1-pre-fix-yPlus.zip) vs [2-post-fix-yPlus.zip](/uploads/f8ee035a427a3c7ea2fefb5d38a40609/2-post-fix-yPlus.zip) (Test: `incompressible/pisoFoam/RAS/cavity`)
- No changes in the default behaviour.
    - User can now select the new behaviour by `useWallFunction=false` which is by default `true`.

Edited Sep 04, 2020 by Kutalmis Bercin