NuSiF CFD Solver

The NuSiF-Solver implements a 3D structured incompressible Navier Stokes solver. This solver uses finite difference discretization using a staggered grid as described in this book by Michael Griebel. The program supports sequential and MPI IO output of the results in VTK file format, that can be visualized using the Paraview application.

Infos

Preconfigured tool chains

• GCC
• CLANG
• ICX

Parallelism

• MPI
• OpenMP

Solvers

• Red-Black SOR
• Geometric Multigrid

Build

1. Configure the tool chain and additional options in config.mk:

# Supported: GCC, CLANG, ICX
TOOLCHAIN ?= GCC
# Supported: true, false
ENABLE_MPI ?= true
ENABLE_OPENMP ?= false
# Supported: rb, mg
SOLVER ?= rb
# Supported: seq, mpi
VTK_OUTPUT_FMT ?= seq

ENABLE_OPENMP ?= false

OPTIONS +=  -DARRAY_ALIGNMENT=64
#OPTIONS +=  -DVERBOSE
#OPTIONS +=  -DVERBOSE_AFFINITY
#OPTIONS +=  -DVERBOSE_DATASIZE
#OPTIONS +=  -DVERBOSE_TIMER

The verbosity options enable detailed output about solver, affinity settings, allocation sizes and timer resolution. For debugging you may want to set the VERBOSE option:

# Supported: GCC, CLANG, ICX
TAG ?= GCC
# Supported: true, false
ENABLE_MPI ?= true
ENABLE_OPENMP ?= false
# Supported: rb, mg
SOLVER ?= rb
# Supported: seq, mpi
VTK_OUTPUT_FMT ?= seq

ENABLE_OPENMP ?= false

OPTIONS +=  -DARRAY_ALIGNMENT=64
OPTIONS +=  -DVERBOSE
#OPTIONS +=  -DVERBOSE_AFFINITY
#OPTIONS +=  -DVERBOSE_DATASIZE
#OPTIONS +=  -DVERBOSE_TIMER

1. Build with:

make

You can build multiple tool chains in the same directory, but notice that the Makefile is only acting on the one currently set. Intermediate build results are located in the ./build/<TOOLCHAIN> directory. The executable is named NusifSolver-<TOOLCHAIN>.

To output all executed commands use:

make Q=

1. Clean up intermediate build results of active tool chain use:

make clean

To clean all build results of all tool chains including all data and visualization output use:

make distclean

1. (Optional) Generate assembler for all source files:

make asm

The assembler files will also be located in the ./build/<TOOLCHAIN> directory.

CLANG tooling support

The Makefile will generate a .clangd configuration to correctly set all options for the clang language server. This is only important if you use an editor with LSP support and want to edit or explore the source code. It is required to use GNU Make 4.0 or newer. While building with older make versions will work, the generation of the .clangd configuration for the clang language server will not work. The default Make version included in MacOS is 3.81! Newer make versions can be easily installed on MacOS using the Homebrew package manager. This will restrict LSP support for all loaded compilation units.

An alternative is to use Bear, a tool that generates a compilation database for clang tooling. This method also will enable to jump to any definition without a previously opened buffer. You have to build one time with Bear as a wrapper:

bear -- make

The repository includes .clang-format and .clang-tidy files to enforce consistent formatting and variable naming.

To reformat all source files use:

make format

This required clang-format in your PATH.

Usage

You have to provide a parameter file describing the problem you want to solve:

./NusifSolver-CLANG dcavity.par

Example test cases are given in the dcavity.par (a lid driven cavity test case) and canal.par (simulating a empty canal) files.

You can plot the resulting residual as a function of iterations using:

make plot