Available Output Fields

Available Output Fields#

This section provides a comprehensive overview of all output fields (flow variables) available in Flow360 simulations, organized by their availability across different output types.

Note: All output fields are non-dimensional by default unless otherwise specified. See Scaling Values and Nondimensionalization for information on converting to dimensional values.

Universal Fields#

These fields are available for all output types.

Field Name	Description	Units
`Cp`	Coefficient of pressure	Non-dimensional
`Cpt`	Coefficient of total pressure	Non-dimensional
`gradW`	Gradient of primitive solution	Non-dimensional
`kOmega`	k and omega (turbulence variables)	Non-dimensional
`Mach`	Mach number	Non-dimensional
`mut`	Turbulent viscosity	Non-dimensional
`mutRatio`	Turbulent viscosity and freestream dynamic viscosity ratio	Non-dimensional
`nuHat`	Spalart-Almaras variable	Non-dimensional
`primitiveVars`	Density, velocities (u,v,w), and pressure	Non-dimensional
`qcriterion`	Q criterion for vortex identification	Non-dimensional
`residualNavierStokes`	Navier-Stokes residual	Non-dimensional
`residualTransition`	Transition residual	Non-dimensional
`residualTurbulence`	Turbulence residual	Non-dimensional
`s`	Entropy	Non-dimensional
`solutionNavierStokes`	Navier-Stokes solution	Non-dimensional
`solutionTransition`	Transition solution	Non-dimensional
`solutionTurbulence`	Turbulence solution	Non-dimensional
`T`	Temperature	Non-dimensional
`velocity`	Velocity vector	Non-dimensional
`velocity_magnitude`	Magnitude of velocity vector	Non-dimensional
`pressure`	Pressure	Non-dimensional
`vorticity`	Vorticity	Non-dimensional
`vorticityMagnitude`	Vorticity magnitude	Non-dimensional
`wallDistance`	Wall distance	Grid unit length
`numericalDissipationFactor`	Numerical dissipation factor sensor	Non-dimensional
`residualHeatSolver`	Heat equation residual	Non-dimensional
`VelocityRelative`	Velocity with respect to non-inertial frame	Non-dimensional
`lowMachPreconditionerSensor`	Low-Mach preconditioner factor	Non-dimensional

VelocityRelative#

This is the relative velocity with respect to the volume zone reference frame. In a rotational domain, the absolute velocity, \(\overrightarrow{\boldsymbol{U}}_\text{absolute}\), of each fluid element could be treated as the summation of a relative velocity, \(\overrightarrow{\boldsymbol{U}}_\text{relative}\), and a velocity due to the rotating frame, \(\overrightarrow{\Omega}\times \overrightarrow{r}\). The “VelocityRelative” means the \(\overrightarrow{\boldsymbol{U}}_\text{relative}\):

\[\overrightarrow{\boldsymbol{U}}_\text{absolute} = \overrightarrow{\boldsymbol{U}}_\text{relative} + \overrightarrow{\Omega}\times \overrightarrow{r}\]

It should be noted that the relative velocity is zero on no-slip walls that are part of the rotating frame (i.e., rotating walls) within rotational blocks. When a wall function is used, this velocity is near zero.

Volume and Slice Specific Fields#

These fields are available only for Volume Output and Slice Output types.

Field Name	Description	Units
`betMetrics`	BET Metrics	Non-dimensional
`betMetricsPerDisk`	BET Metrics per Disk	Non-dimensional
`linearResidualNavierStokes`	Linear residual of Navier-Stokes solver	Non-dimensional
`linearResidualTurbulence`	Linear residual of turbulence solver	Non-dimensional
`linearResidualTransition`	Linear residual of transition solver	Non-dimensional
`SpalartAllmaras_hybridModel`	Hybrid RANS-LES output for Spalart-Allmaras solver (supports both DDES and ZDES)	Non-dimensional
`kOmegaSST_hybridModel`	Hybrid RANS-LES output for kOmegaSST solver (supports both DDES and ZDES)	Non-dimensional
`localCFL`	Local CFL number	Non-dimensional

Hybrid RANS-LES Output Variables#

The SpalartAllmaras_hybridModel and kOmegaSST_hybridModel output fields provide diagnostic variables for hybrid RANS-LES simulations. The specific variables included depend on whether you’re using DDES (Delayed Detached Eddy Simulation) or ZDES (Zonal Detached Eddy Simulation) as the shielding function.

DDES Variables (when `shielding_function="DDES"`)#

When using DDES, the hybrid model output includes five key variables:

f_d – The shielding function that delineates the RANS and LES regions. When f_d = 0, the RANS model is fully applied; when f_d = 1, the LES model is used. Intermediate values represent a smooth transition between the two regimes.
r_d – A modified ratio of the modeled length scale to the wall distance, from which f_d is derived.
DDES_lengthRANS – The wall distance from the computational cell to the nearest solid boundary.
DDES_lengthScale – The characteristic DES length scale: \(\tilde{d} \equiv d - f_d \max(0, d - C_{DES}*\Delta)\)
DDES_lengthLES – The characteristic LES length scale: \(C_{DES}*\Delta\)

Among these variables, f_d is the most significant, as it enables users to identify and visualize the regions dominated by RANS and DES behavior within the computational domain.

ZDES Variables (when `shielding_function="ZDES"`)#

When using ZDES, the hybrid model output includes four key variables:

ZDES_fp – The enhanced shielding function that determines whether RANS or LES is used. When ZDES_fp = 0, RANS is active; when ZDES_fp = 1, LES is active. This function is computed from ZDES_fd, ZDES_fR, and ZDES_fp2.
ZDES_fd – Original DDES shielding function used in computing ZDES_fp.
ZDES_fR – Component used in computing ZDES_fp. This is included to disable or inhibit the second shielding function in regions where vorticity magnitude is increasing away from walls - this is designed to disable the secondary shielding function where a shear layer is detected above a wall.
ZDES_fp2 – Causes the model to revert to RANS mode in the outer portion of boundary layers, used in computing ZDES_fp.

Surface Specific Fields#

These fields are available only for Surface Output and Surface Probe Output types.

Field Name	Description	Units
`CfVec`	Skin friction coefficient vector	Non-dimensional
`Cf`	Magnitude of skin friction coefficient	Non-dimensional
`heatFlux`	Non-dimensional heat flux	Non-dimensional
`nodeNormals`	Wall normals	Non-dimensional
`nodeForcesPerUnitArea`	Forces per unit area	Non-dimensional
`yPlus`	Non-dimensional wall distance	Non-dimensional
`wallFunctionMetric`	Wall function metrics	Non-dimensional
`heatTransferCoefficientStaticTemperature`	Surface heat transfer coefficient (static temperature as reference)	Non-dimensional
`heatTransferCoefficientTotalTemperature`	Surface heat transfer coefficient (total temperature as reference)	Non-dimensional
`wall_shear_stress_magnitude`	Wall shear stress magnitude	Non-dimensional
`wall_shear_stress_magnitude_pa`	Wall shear stress magnitude	Pascals (Pa) - Available since version 25.2

Isosurface Specific Fields#

These fields are available only for Isosurface Output types.

Visualization Tips#

Isosurface outputs support all universal fields listed above. The most commonly used fields for isosurface visualization are:

qcriterion - For vortex identification
Mach - For shock wave visualization
pressure - For pressure-based isosurfaces
Cpt - For total pressure loss visualization

Custom Variables#

User-defined expressions with dimensions. These can be created using the Variable Settings tool or Python API.

By default, the following expressions are available:

Variable Name	Expression	Description
`velocity_with_units`	`solution.velocity`	Velocity in physical units
`velocity_magnitude_with_units`	`math.magnitude(solution.velocity)`	Velocity magnitude in physical units
`pressure_with_units`	`solution.pressure`	Pressure in physical units
`wall_shear_stress_magnitude_with_units`	`solution.wall_shear_stress_magnitude`	Wall shear stress magnitude in physical units

Note: You can create additional custom variables using the Variable Settings tool or through the Python API. Custom variables can access multiple solver variables and undergo mathematical operations.