LES-model (incompressible 3D LES)

Small 3D Large-Eddy Simulation (LES) prototype written in C++. Features:

• 3D structured grid solver (u,v,w,p) with Smagorinsky SGS model
• Explicit momentum update
• Pressure Poisson solver (Jacobi, GS SOR, PCG with Jacobi, IC and Chebyshev preconditioners)
• Restart/continue from previous step checkpoint in .data and .meta files
• OpenMP parallelization

Prerequisites

• C++17-capable compiler (g++ recommended)
• OpenMP support
• make

Build

• From project root:
  • make
  • Executable: bin/les_solver

Run

• Default run:
  • make run or ./bin/les_solver
• On start the program prompts:
  • c to continue from latest checkpoint/checkpoint.data and checkpoint/checkpoint.meta(if present)
  • r to restart from scratch

I/O

• Output VTK files written to output/output_<step>.vtk (ASCII STRUCTURED_POINTS)
  • Contains velocity VECTORS, pressure SCALARS, nu_t and solid mask
• The program can read the VECTORS and pressure blocks to resume a simulation.
• To continue, keep output/ files and start with the c option.

Project layout

• src/ : source files
• build/ : object files (created by Makefile)
• bin/ : executable
• checkpoint/ : checkpoint data from continuation of simulation supporting graceful termination Ctrl + C
• output/ : VTK outputs (ignored by .gitignore)

Makefile

• Uses g++ -std=c++17 -fopenmp (see Makefile for flags)
• To change compiler flags edit Makefile variable CXXFLAGS.

DONE:

• Graceful shutdown
• Correct checkpoint saving all Field with precision
• IC(0) preconditioner for PCG for pressure laplacian solver
• Chebyshev preconditioner for PCG for pressure laplacian solver
• Statistic for time-average flow after nsteps

TODO

• Implement SOTA multigrid solver for Pressure
• Semi-implicit methods for momentum: Convection Explicitly, Diffusion Implicitly
• Conservative equation form
• Continue to unorganized mesh and FVM