Changes in Version 8

SU2 version 8 (“Harrier”) started with v8.0.0 in August 2023. Most v7 config files still run in v8. A few options were renamed or removed, some defaults changed, and several fixes change the results of turbulent cases. The Python wrapper and the build system also changed.

How to read this page:

  • Read Breaking changes first. These can stop a v7 config from running or change its results.
  • New features lists what v8 adds, by area. Each item gives the release that added it.
  • Use the checklist at the end to update a config.

When SU2 finds a removed option in a config file, it stops and names the option. For many options it also names the replacement. The full list of renamed and removed options is on Renamed and Removed Options. The changes from v6 to v7 (EXT_ITER, PHYSICAL_PROBLEM, output options and so on) are on Guide to Version v7.

Breaking changes

Renamed and removed options

These are the most common ones. See Renamed and Removed Options for all of them.

Old option New option Release
DYNAMIC_ANALYSIS TIME_DOMAIN v8.0.0
DYN_TIMESTEP TIME_STEP v8.0.0
DYN_TIME MAX_TIME v8.0.0
SINGLEZONE_DRIVER Removed, no replacement v8.0.0
SPECIES_USE_STRONG_BC= YES MARKER_SPECIES_STRONG_BC= (marker1, ...) v8.0.0
DEAD_LOAD GRAVITY_FORCE or BODY_FORCE v8.2.0
SMOOTH_GEOMETRY Removed (it had no effect) v8.2.0
INC_INLET_USENORMAL INLET_USE_NORMAL (now works for all solvers) v8.3.0
RAMP_OUTLET_PRESSURE, RAMP_OUTLET_PRESSURE_COEFF RAMP_OUTLET, RAMP_OUTLET_COEFF v8.3.0
RAMP_ROTATING_FRAME, RAMP_ROTATING_FRAME_COEFF RAMP_MOTION_FRAME, RAMP_MOTION_FRAME_COEFF v8.3.0
DATADRIVEN_INITIAL_DENSITY, DATADRIVEN_INITIAL_ENERGY (added in v8.2.0) Removed, no replacement v8.5.0

The FEA solver now uses the same time options as the flow solver. A dynamic structural case needs TIME_DOMAIN= YES, TIME_STEP and MAX_TIME.

Removed option values (v8.0.0):

  • CONV_NUM_METHOD_FLOW= CUSP. Use JST or an upwind scheme.
  • TIME_DISCRE_FEA= CD_EXPLICIT and GENERALIZED_ALPHA. Only NEWMARK_IMPLICIT is left.
  • DV_KIND= FFD_TWIST_2D. It was never implemented.
  • OBJECTIVE_FUNCTION= FLOW_ANGLE_OUT and MASS_FLOW_IN (turbomachinery).

These turbulence settings changed in v7.4.0. The v7 guide does not cover them, and older v7 configs may still use them:

Old setting New setting
KIND_TURB_MODEL= SA_NEG KIND_TURB_MODEL= SA, SA_OPTIONS= NEGATIVE, WITHFT2
KIND_TURB_MODEL= SA_E KIND_TURB_MODEL= SA, SA_OPTIONS= EDWARDS
KIND_TURB_MODEL= SA_COMP KIND_TURB_MODEL= SA, SA_OPTIONS= COMPRESSIBILITY
KIND_TURB_MODEL= SA_E_COMP KIND_TURB_MODEL= SA, SA_OPTIONS= EDWARDS, COMPRESSIBILITY, EXPERIMENTAL
KIND_TURB_MODEL= SST_SUST KIND_TURB_MODEL= SST, SST_OPTIONS= SUSTAINING
KIND_TRANS_MODEL= BC KIND_TURB_MODEL= SA, SA_OPTIONS= BCM

The SA_NEG row selects standard SA-neg, including ft2. To request negative SA without ft2, use SA_OPTIONS= NEGATIVE, EXPERIMENTAL; this is a different formulation and can change the results. Edwards with a compressibility correction also needs EXPERIMENTAL, because it is not a standard TMR combination. See Turbulence Models.

Changed defaults and behaviour

What Before Now Release
SST version when SST_OPTIONS names none SST-1994m SST-2003m v8.0.0
MUSCL_FLOW= YES (or MUSCL_ADJFLOW= YES) with a centered scheme Ignored Error. Remove the line or set it to NO. v8.0.0
Restart files (WRT_RESTART_COMPACT, new option, default YES) All volume output fields Only the fields needed to restart v8.2.0
Default file names (RESTART_FILENAME, SOLUTION_FILENAME, …) restart.dat, solution.dat, … restart, solution, … SU2 adds the extension. v8.3.0
MGLEVEL Exact number of coarse levels Maximum. Levels with fewer than MG_MIN_MESHSIZE (500) points are dropped. v8.5.0
MG_PRE_SMOOTH, MG_POST_SMOOTH Fixed number of smoothing steps Maximum. The smoother stops early (MG_SMOOTH_EARLY_EXIT= YES). v8.5.0
MG_DAMP_RESTRICTION, MG_DAMP_PROLONGATION 0.75, fixed 0.5, used as a start value and adapted during the run v8.5.0

Notes:

  • SST. To keep the old model, set SST_OPTIONS= V1994m. In v8.0.0 the 1994m model itself also changed to match the literature, so old SST-1994m results are not reproduced exactly.
  • Restart files. With compact restarts, extra fields such as pressure or skin friction are no longer in the restart file. They are still in the visualization files. Set WRT_RESTART_COMPACT= NO if your scripts read these fields from the restart file. See Restart File.
  • File names. Give file names without an extension. If you give the expected extension, SU2 removes it. A different extension stays part of the name.
  • Multigrid. MG_SMOOTH_EARLY_EXIT= NO gives fixed smoothing and fixed damping again. To also get the old damping values, set MG_DAMP_RESTRICTION and MG_DAMP_PROLONGATION to 0.75.

Changes that affect results

Many fixes in v8 change the converged solution a little, mostly for turbulent flows. Do not expect v7 and v8 to give the same forces. The main ones:

  • SST: the default changed to SST-2003m and SST-1994m was corrected (v8.0.0). SST-2003 had important fixes (v8.2.0). The cross-diffusion term has a new discretization (v8.3.0).
  • SA: corrections to the SA and SA-neg models (v8.0.0, v8.1.0). The nonlinear diffusion term has a new discretization (v8.3.0).
  • Symmetry planes: corrected (v8.1.0). Intersecting and curved symmetry planes and inviscid walls work better (v8.2.0).
  • Multigrid: new smoothing and damping rules (v8.5.0), see above.

Python wrapper

The Python wrapper was rewritten in v8.0.0. Scripts written for v7 need changes. Many methods have new names, for example:

v7 v8
Postprocessing() Finalize()
GetNumberVertices(iMarker) GetNumberMarkerNodes(iMarker)
SetVertexTemperature(...) SetMarkerCustomTemperature(...)

Methods that set boundary conditions now start with SetMarkerCustom. The Python wrapper test cases show the current interface.

Build and tools

  • The old autotools build (configure, make) was removed in v8.0.0. Build with meson. See Build SU2 on Linux/MacOS.
  • Some old Python scripts were removed in v8.0.0: compute_multipoint.py, compute_stability.py, config_gui.py and convert_to_csv.py.
  • v8.5.0 uses PaStiX version 6 (-Denable-pastix=true) and CoolProp 7.2.0. The release binaries now include OpenMP, and the default compiler optimization is stronger.

New features by area

Many bug fixes and small improvements are not listed. See the GitHub release notes for all changes.

Solvers and models

  • Combustion. Flamelet model for premixed flames: KIND_SCALAR_MODEL= FLAMELET with FLUID_MODEL= FLUID_FLAMELET (v8.0.0). Preferential diffusion (PREFERENTIAL_DIFFUSION) and spark ignition (FLAME_INIT_METHOD= SPARK) (v8.1.0). See Species Transport and Combustion and the tutorials Laminar Combustion and Counterflow Diffusion Flame.
  • Data-driven fluid model. FLUID_MODEL= DATADRIVEN_FLUID with look-up tables or neural networks (INTERPOLATION_METHOD= LUT or MLP) (v8.0.0). Physics-informed networks with USE_PINN (v8.2.0). See NICFD and the tutorial Physics-informed neural networks.
  • Species transport. Custom wall conditions with MARKER_WALL_SPECIES (v8.4.0). Adaptive CFL now also covers species (v8.1.0).
  • NEMO. Ionization for viscous flows (v8.0.0). See Thermochemical Nonequilibrium.
  • SST. Compressibility corrections SST_OPTIONS= COMPRESSIBILITY-WILCOX or COMPRESSIBILITY-SARKAR (v8.1.0). Lower limits relative to the free stream with SST_OPTIONS= DIMENSIONLESS_LIMIT, LOWER_LIMIT_K_FACTOR and LOWER_LIMIT_OMEGA_FACTOR (v8.1.0). Rough-wall models with KIND_ROUGHSST_MODEL and WALL_ROUGHNESS (v8.4.0).
  • SA. Source terms for 2D axisymmetric flows (v8.1.0).
  • Hybrid RANS/LES. Stochastic backscatter model (STOCHASTIC_BACKSCATTER), ENFORCE_LES, LES_FILTER_WIDTH and the low-dissipation scheme LD2 (v8.5.0). See Unsteady and DES.
  • Compressible flow. Conductivity models other than CONSTANT_PRANDTL (CONDUCTIVITY_MODEL) (v8.4.0).
  • Incompressible flow. Temperature limits with TEMPERATURE_LIMITS (v8.4.0). Preconditioning for multicomponent flows (v8.4.0). See Incompressible.
  • Boundary conditions. SA inlet based on local conditions (v8.0.0). Supersonic inlet profiles (v8.1.0). INLET_USE_NORMAL for compressible inlets (v8.3.0).
  • Actuator disks and engines. Blade element actuator disk, ACTDISK_TYPE= BLADE_ELEMENT (v8.0.1). Engine mass flow coupling for zero-thrust cases, ENGINE_EXHAUST_TO_INLET (v8.5.0).
  • Gusts. Gust encounter for 3D meshes and free-flying elastic aircraft, GUST_DIR= Z_DIR (v8.0.0).
  • Turbomachinery. New turbomachinery outputs (v8.0.1). New interfaces between rows and TURBO_PERF_KIND (v8.1.0). New ramps (v8.3.0, v8.4.0). See Turbomachinery and the tutorial Aachen Turbine.
  • Structural solver. Thermal expansion (MATERIAL_THERMAL_EXPANSION_COEFF, MATERIAL_REFERENCE_TEMPERATURE) and centrifugal forces (CENTRIFUGAL_FORCE) (v8.2.0).
  • Stopping a run. SIGTERM stops the run and writes the output files (v8.1.0).

Numerics

  • Limiters. Nishikawa limiters NISHIKAWA_R3, NISHIKAWA_R4 and NISHIKAWA_R5 (v8.0.0). See Slope Limiters.
  • MUSCL. Kappa scheme with MUSCL_KAPPA_FLOW, MUSCL_KAPPA_TURB and related options (v8.4.0). The default 0 keeps the previous scheme. MUSCL ramp with RAMP_MUSCL and KIND_MUSCL_RAMP (v8.4.0).
  • MSW scheme. Uses a pressure sensor, set with MSW_ALPHA (v8.5.0). See Convective Schemes.
  • CFL. CFL_ADAPT_PARAM takes a sixth value: the iteration where adaptation starts (v8.2.0).
  • Robustness. Limits on the solution update: MAX_UPDATE_FLOW, MAX_UPDATE_SA, MAX_UPDATE_SST. Exact turbulence Jacobians with USE_ACCURATE_TURB_JACOBIANS (v8.3.0).
  • Linear solvers. LINEAR_SOLVER= FGCRODR with LINEAR_SOLVER_RESTART_DEFLATION (v8.4.0). Nested preconditioning with LINEAR_SOLVER_INNER (v8.4.0). Newton-Krylov improvements (v8.4.0). Level scheduling for OpenMP ILU, LINEAR_SOLVER_ILU_LEVEL_SCHEDULING (v8.5.0). See Linear Solvers and Preconditioners.
  • Multigrid. New options MG_MIN_MESHSIZE, MG_SMOOTH_EARLY_EXIT, MG_SMOOTH_RES_THRESHOLD and MG_SMOOTH_COEFF (v8.5.0).
  • Mesh deformation and shape design. RBF mesh deformation, DEFORM_KIND= RBF (v8.3.0). Camber line Hicks-Henne design variable, DV_KIND= HICKS_HENNE_CAMBER (v8.3.0). See Shape Optimization.

Output

  • Custom outputs (functions of other outputs) with CUSTOM_OUTPUTS, for all solvers (v8.0.0). See Custom Output.
  • New volume fields: local time step and CFL, velocity for compressible flow, thermal conductivity, heat capacity and diffusivity (v8.0.0).
  • CUR_TIME is in the default history output of unsteady runs (v8.0.1). ITER_TIME gives the wall time per iteration (v8.5.0).
  • Compact restart files and VOLUME_OUTPUT= COMPACT (v8.2.0).
  • Wall heat fluxes are reported as imposed by the wall boundary condition (v8.2.0).

Adjoint and AD

  • Faster hybrid parallel (MPI + OpenMP) discrete adjoint (v8.0.0, v8.0.1).
  • Tape debug mode with CHECK_TAPE_TYPE and CHECK_TAPE_VARIABLES (v8.3.0).
  • Discrete adjoint of thermoelastic problems (v8.5.0). The Newton-Krylov adjoint uses FGCRODR (v8.5.0).
  • The FADO optimization framework is installed with SU2 (v8.2.0).

Multizone and multiphysics

  • Solid-to-solid heat transfer with contact resistance, CHT_INTERFACE_CONTACT_RESISTANCE (v8.1.0). See the tutorial Contact Resistance CHT.
  • Coupled thermoelasticity (v8.2.0). MARKER_CREATE_COPY makes thermoelastic setups simpler (v8.5.0).
  • See Multizone and Heat Transfer and CHT.

Performance

  • FGMRES on GPUs with CUDA: build with -Denable-cuda=true and set ENABLE_CUDA= YES (v8.3.0).
  • Better OpenMP performance: adaptive edge color group size (v8.0.1) and more parallel regions.
  • Profiling with Tracy (v8.3.0) and gprof (-Denable-gprof=true, v8.1.0). See Tracy Integration.

Python wrapper

  • Rewritten in v8.0.0. Python scripts can deform the mesh in memory, read and set the solution and primitive variables in the volume and on markers, read all history outputs, set custom boundary conditions, set the angles of attack and sideslip, and choose the zone in multizone cases.
  • Custom inlets (v8.1.0). Custom source terms for all solvers with PYTHON_CUSTOM_SOURCE (v8.3.0). Source terms for the heat solver (v8.4.0).
  • See Execution and the tutorials Dynamic FSI with Python and User Defined Combustion Model.

Migrating a v7 config

  1. Run the config with v8. SU2 lists every unknown option and often the replacement. Fix them with the tables above and Renamed and Removed Options.
  2. For FEA dynamic cases, replace DYNAMIC_ANALYSIS, DYN_TIMESTEP and DYN_TIME with TIME_DOMAIN, TIME_STEP and MAX_TIME.
  3. For SST cases, decide on the version. Add SST_OPTIONS= V1994m only if you must stay close to old results. Otherwise use the new default, SST-2003m.
  4. Replace KIND_TURB_MODEL values like SA_NEG or SST_SUST with SA_OPTIONS or SST_OPTIONS.
  5. Remove MUSCL_FLOW= YES from cases with a centered scheme (JST, LAX-FRIEDRICH). Replace CUSP with another scheme.
  6. If you read fields other than the solution from restart files, set WRT_RESTART_COMPACT= NO.
  7. Write file names without an extension.
  8. With multigrid, check the number of levels SU2 prints at the start. Set MG_SMOOTH_EARLY_EXIT= NO if you need the old smoothing.
  9. Update Python wrapper scripts to the new method names.
  10. Build from source with meson, not autotools.
  11. Compare the results with your v7 results. Small differences are expected for turbulent cases.

Last checked against SU2 release v8.5.0.


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