https://github.com/zoziha/nnps
NNPS scheme practice in CFD particle method.🌲
https://github.com/zoziha/nnps
fortran fpm nnps quad-tree
Last synced: 12 days ago
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NNPS scheme practice in CFD particle method.🌲
- Host: GitHub
- URL: https://github.com/zoziha/nnps
- Owner: zoziha
- License: mit
- Created: 2021-09-25T02:05:00.000Z (over 3 years ago)
- Default Branch: main
- Last Pushed: 2024-01-15T04:46:33.000Z (over 1 year ago)
- Last Synced: 2025-05-22T21:15:59.693Z (about 1 month ago)
- Topics: fortran, fpm, nnps, quad-tree
- Language: Fortran
- Homepage:
- Size: 182 KB
- Stars: 3
- Watchers: 1
- Forks: 0
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# Nearest Neighbor Particle Search
[](LICENSE)
NNPS scheme practice in CFD particle method.
## Usage
Only [FPM]((https://github.com/fortran-lang/fpm))/Meson/Visual-Studio are supported,
other build systems can copy source files directly,
and `ifort/ifx` and `gfortran` compilers are tested.
To use `nnps` within your `fpm` project, add the following lines to your `fpm.toml` file:
```sh
[dependencies]
nnps = { git="https://github.com/zoziha/nnps" }
```
**Note: Windows-ifort bug, Using static compilation will cause problems with allocatable arrays! Please use the `/libs:dll` compile option!**
### Parallel
For 2D/3D NNPS, OpenMP is used for parallel acceleration, and parallel threads can be set through the `OMP_NUM_THREADS` environment variable.
## Example
```sh
> fpm run --example --all # run all examples
```
```fortran
program example_grid2d
use nnps_module, only: nnps_grid2d, wp
use display_module, only: display
implicit none
type(nnps_grid2d) :: nnps
real(wp), dimension(2, 4) :: loc = reshape([0.0_wp, 1.0_wp, 2.0_wp, 1.5_wp, &
1.0_wp, 1.0_wp, 0.5_wp, 1.0_wp], [2, 4])
integer, pointer :: pairs(:)
real(wp), pointer :: rdxs(:)
call nnps%init(loc, n=4)
call nnps%query(0.6_wp, pairs, rdxs, n=4)
print *, '*** grid find (2D)'
call display(pairs, 'pairs index:', brief=.false.)
call display(loc(:, pairs), 'pairs coordinates:', brief=.false.)
call display(rdxs, 'rdxs:', brief=.false.)
end program example_grid2d
! *** grid find (2D)
! [vector: 4] pairs index:
! 3, 4, 4, 1
! [matrix: 2*4] pairs coordinates:
! 1.000E+00, 5.000E-01, 5.000E-01, 0.000E+00;
! 1.000E+00, 1.000E+00, 1.000E+00, 1.000E+00
! [vector: 6] rdxs:
! 5.000E-01, 5.000E-01, 0.000E+00, 5.000E-01, 5.000E-01, 0.000E+00
```
Originally a study of the NNPS algorithm for SPH particle methods, this library has now been introduced into the SPH code, see [zoziha/SPH](https://github.com/zoziha/SPH).
## Links
+ [wikipedia/Quadtree](https://en.wikipedia.org/wiki/Quadtree)
+ [lewisfish/quad-tree](https://github.com/lewisfish/quad-trees)
+ [bilibili/Dejavu32/[Coding Challenge ]:四叉树的实现 以及 碰撞检测应用（Quadtree Collisions )](https://www.bilibili.com/video/BV1ub411S7N5?spm_id_from=333.999.0.0)
+ [CodingTrain/QuadTree](https://github.com/CodingTrain/QuadTree)