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Accurate Implicit Three-dimensional Efficient RANS (AITHER)

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About The Code

Aither is a 3D Navier-Stokes computational fluid dynamics solver capable of modeling finite rate chemsitry. It is a cell centered, structured solver, using multi-block structured grids in Plot3D format. It uses explicit and implicit time integration methods. It uses MUSCL extrapolation to reconstruct the primitive variables from the cell centers to the cell faces for 2nd order accuracy. Higher order reconstruction is acheived with a 5th order WENO reconstruction for the inviscid fluxes, and a 4th order central reconstruction for the viscous fluxes. The code uses either the Roe flux difference splitting or AUSMPW+ flux vector splitting scheme for the inviscid fluxes, and a central scheme for the viscous fluxes. It is second order accurate in both space and time.

Current Status

The code is 2nd order accurate in space and time. Available explicit time integration methods are forward euler (1st order) and a minimum storage four stage Runge-Kutta method (2nd order). The implicit solver (LU-SGS, BLU-SGS, DPLUR, BDPLUR) is implemented for implicit time integration. Dual time stepping is implemented for time accuracy in the implicit solver. Available implicit time integration methods come from the Beam and Warming family of methods and are the implicit euler (1st order), Crank-Nicholson (2nd order), and BDF2 (2nd order) methods. The code has been thoroughly commented. It has been made parallel using MPI. For RANS simulations the Wilcox K-Omega 2006 and SST 2003 turbulence models are available. Wall functions are supported for both models. For detatched eddy simulations, the SST-DES turbulence model is available. For large eddy simulations, the WALE subgrid scale model is available. Multispecies flow is supported and a Schmidt number based model is used for diffusion. Reacting flow is modeled with a finite rate chemistry model.

To Do List

  • Performance improvements
  • User guide


  • MPI - OpenMPI, MPICH, & MS-MPI have been used
  • C++ compiler with C++14 support
  • Cmake - Cmake only depends on a C++ compiler

How To Compile And Install

Aither is compiled and installed with the standard cmake process.

cmake -DCMAKE_INSTALL_PREFIX=/path/to/installation -DCMAKE_BUILD_TYPE=release /path/to/source
make install

export AITHER_INSTALL_DIRECTORY=/path/to/installation

Cmake will automatically look for an MPI package. To specify a specific installation, set -DMPI_DIR to the MPI installation directory. In addition to release, other supported build types are debug, profile, relwithdebinfo, and minsizerel.

How To Run

mpirun -np 1 aither inputFile.inp [restartFile.rst] > outputFile.out 2> errorFile.err &

The restart file argument is optional.

Visualizing Results

Aither writes out Plot3D function files (*.fun), as well as a Plot3D meta files (*.p3d) that can be visualized in ParaView. Versions 5.3 and newer support reading the meta files.