GitHub - NaokiHori/VerySimpleNSSolver: A library-free and extremely simple two-dimensional incompressible Navier-Stokes solver

Very Simple NS Solver

An extremely simple two-dimensional incompressible Navier-Stokes solver designed to test various numerical algorithms.

Concept

The primary goal of this library is simplicity, allowing numerical methods, especially for multi-phase flows, to be easily and quickly implemented and tested without being encumbered by sub-critical tasks. To achieve this, the following approaches are adopted:

Euler-forward time-stepping
Fully-explicit diffusive treatments
No multi-process (e.g., MPI) parallelization

For the sake of transparency (and for fun), in-house Fourier transforms, linear matrix solvers, and matrix transpose routines are used, despite their sub-optimal performance.

Dependencies

Quick Start

Clone the repository:

git clone https://github.com/NaokiHori/VerySimpleNSSolver
cd VerySimpleNSSolver

Build the project:

If your platform supports OpenMP:
```
make ARG_CFLAG="-fopenmp" all
```
Alternatively, you can directly modify the Makefile.
Run the solver:

If your platform supports OpenMP:
```
make output
OMP_NUM_THREADS=4 ./a.out
```
(This example uses four threads.)

Domain Size

The domain sizes (spatial resolutions and lengths) are defined in src/domain.c. Modify the corresponding parameter and re-build the source.

Multi-thread Parallelization

Even in two-dimensional domains, some level of parallelization is necessary. This project utilizes OpenMP for parallelization for convenience.

Note

For simplicity, all flow fields have domain->nx + 2 by domain->ny + 2 elements, regardless of the type of arrays. Here, domain->nx and domain->ny represent the degrees of freedom in the x and y directions, respectively. This approach simplifies the incorporation of different boundary conditions (wall-bounded, periodic, inflow-outflow).