Materials
Where it is
Section titled “Where it is”Setup tree: Materials
Controls
Section titled “Controls”Material
Section titled “Material”- Control: choice (
ComboRow) - Default:
Air (incompressible) - Bound to:
CaseState.fluidName - Options:
Air (incompressible),Air (ideal gas),Water (15 °C),Seawater (1025 kg/m³),Ethylene glycol 50%,Engine oil (SAE 30),Custom
From the bundled material library, with a valid temperature range and a source citation.
Density
Section titled “Density”- Control: value (
ValueField) - Unit: kg/m³
- Default:
1.225 - Bound to:
CaseState.fluidRho - Writes:
used for forceCoeffs rhoInf and the Pa → kinematic conversion
Kinematic ν
Section titled “Kinematic ν”- Control: value (
ValueField) - Unit: m²/s
- Default:
1.51e-5 - Bound to:
CaseState.fluidNu - Writes:
transportProperties/nu
Speed of sound c₀
Section titled “Speed of sound c₀”- Control: value (
ValueField) - Unit: m/s
- Default:
343.0 - Bound to:
CaseState.speedOfSound - Writes:
transportProperties/c0 - Shown when:
CaseState.solver === "acousticFoam"
The wave speed acousticFoam propagates. Not derived from ν - about 343 m/s in air at 20 °C, and 1480 m/s in water.
Buoyancy
Section titled “Buoyancy”Expansion β
Section titled “Expansion β”- Control: value (
ValueField) - Unit: 1/K
- Default:
3.0e-3 - Bound to:
CaseState.fluidBeta - Writes:
transportProperties/beta - Shown when:
CaseState.energyEnabled || CaseState.gravityEnabled
Thermal expansion. The buoyant force is β(T − TRef)g, so this is what makes hot fluid rise. About 3.3e-3 for air at room temperature and 2.1e-4 for water - a factor of fifteen.
Reference T
Section titled “Reference T”- Control: value (
ValueField) - Unit: K
- Default:
300 - Bound to:
CaseState.fluidTRef - Writes:
transportProperties/TRef - Shown when:
CaseState.energyEnabled || CaseState.gravityEnabled
The temperature at which the fluid is neutrally buoyant. Usually the ambient or inlet temperature; only differences from it produce a force.
Turbulent Pr
Section titled “Turbulent Pr”- Control: value (
ValueField) - Default:
0.85 - Bound to:
CaseState.fluidPrt - Writes:
transportProperties/Prt - Shown when:
CaseState.energyEnabled || CaseState.gravityEnabled
How readily turbulence carries heat compared with momentum. 0.85 is the usual value and is rarely worth changing.
Thermophysics
Section titled “Thermophysics”Ambient p
Section titled “Ambient p”- Control: value (
ValueField) - Unit: Pa
- Default:
101325 - Bound to:
CaseState.ambientPressure - Writes:
0/p internalField - Value modes: none (plain entry)
- Shown when:
CaseState.compressible
Absolute, not gauge. A compressible solver works in absolute Pa, so a gauge zero is one atmosphere — writing zero would give it a fluid with no density.
Molar mass
Section titled “Molar mass”- Control: value (
ValueField) - Unit: g/mol
- Default:
28.96 - Bound to:
CaseState.fluidMolWeight - Writes:
thermophysicalProperties/mixture/specie/molWeight - Value modes: none (plain entry)
- Shown when:
CaseState.compressible
- Control: value (
ValueField) - Unit: J/kg/K
- Default:
1004.5 - Bound to:
CaseState.fluidCp - Writes:
thermophysicalProperties/mixture/thermodynamics/Cp - Value modes: none (plain entry)
- Shown when:
CaseState.compressible
Sutherland As
Section titled “Sutherland As”- Control: value (
ValueField) - Default:
1.4792e-06 - Bound to:
CaseState.fluidSutherlandAs - Writes:
thermophysicalProperties/mixture/transport/As - Value modes: none (plain entry)
- Shown when:
CaseState.compressible
mu = As sqrt(T) / (1 + Ts/T). The air defaults are 1.4792e-06 and 116 K.
Sutherland Ts
Section titled “Sutherland Ts”- Control: value (
ValueField) - Unit: K
- Default:
116.0 - Bound to:
CaseState.fluidSutherlandTs - Writes:
thermophysicalProperties/mixture/transport/Ts - Value modes: none (plain entry)
- Shown when:
CaseState.compressible
Full thermophysics for heat transfer
Section titled “Full thermophysics for heat transfer”- Control: on/off (
ToggleRow) - Default:
false - Bound to:
CaseState.compressibleBuoyancy - Shown when:
CaseState.analysisType === "Convective Heat Transfer"
Boussinesq treats density as constant except in the buoyancy term, which holds while the temperature rise is small — past roughly 30 K it stops holding and this is the honest choice.
Regions
Section titled “Regions”+ Fluid region
Section titled “+ Fluid region”- Control: action (
ToolButton2)
+ Solid region
Section titled “+ Solid region”- Control: action (
ToolButton2)
Conditional and repeated groups
Section titled “Conditional and repeated groups”Per item in CaseState.multiRegion ? CaseState.regions : 0
Section titled “Per item in CaseState.multiRegion ? CaseState.regions : 0”repeated once for every entry in CaseState.multiRegion ? CaseState.regions : 0
- Control: value (
ValueField) - Value modes: none (plain entry)
Must match the cellZone the mesh carries — that is what splitMeshRegions names the region after.
Initial T
Section titled “Initial T”- Control: value (
ValueField) - Unit: K
- Value modes: none (plain entry)
Material
Section titled “Material”- Control: value (
ValueField) - Value modes: none (plain entry)
- Shown when:
regionRow.model.type === "solid"
Density
Section titled “Density”- Control: value (
ValueField) - Unit: kg/m3
- Default:
8000 - Writes:
thermophysicalProperties/mixture/equationOfState/rho - Value modes: none (plain entry)
- Shown when:
regionRow.model.type === "solid"
- Control: value (
ValueField) - Unit: J/kg/K
- Default:
450 - Value modes: none (plain entry)
- Shown when:
regionRow.model.type === "solid"
Conductivity
Section titled “Conductivity”- Control: value (
ValueField) - Unit: W/m/K
- Default:
80 - Writes:
thermophysicalProperties/mixture/transport/kappa - Value modes: none (plain entry)
- Shown when:
regionRow.model.type === "solid"
Isotropic and constant. Steel is about 45, aluminium about 200, a typical plastic about 0.2.
Problems reported against this step
Section titled “Problems reported against this step”The application checks these before a run and reports them in the Problems tab against this step.
| Severity | Message |
|---|---|
| error | Both phases are called ‘…’. The names become field names, so they have to differ. |
| warning | The domain starts entirely …. Set a fill level, or add an initialisation region, or the run has no … in it to move. |
| warning | The wave is as tall as the water is deep. That is past breaking, and no regular wave theory holds there. |
| error | The dispersed phase ‘…’ is not one of the two phases. |
| error | Particles are injected through a patch the case does not have. |
| error | The minimum particle diameter is larger than the maximum. |
| error | A reacting case needs at least a fuel and an oxidiser in the species list. |
| error | ‘…’ is named as fuel, oxidiser or inert but is not in the species list. |
| error | The roughness length z0 has to be greater than zero; the logarithmic profile divides by it. |
| warning | The reference height is at or below the roughness length, where the profile is not defined. |
| error | The transported scalar has no name, so no field is written. |
| error | The solid region “…” covers the whole domain, so there would be no fluid left. Give it a box or sphere inside the domain. |
… marks a value the application computes at run time, so the source carries no fixed text for it.