fix(): temperature_offset has same unit conversion as temperature (#668)

* Rename stuff

* Ready for review

* added some unit test

* Added scaling test for this new temperature_difference non-dimensionalization

* Comments addressed

* Fixed delta character not recognized in the Windows OS

* More fix

examples/migration_guide/extra_operating_condition.py

@@ -9,9 +9,9 @@
     ThermalState,
 )
 from flow360.component.simulation.unit_system import (
+    AbsoluteTemperatureType,
     AngleType,
     LengthType,
-    TemperatureType,
 )
 from flow360.log import log
 
@@ -24,7 +24,7 @@ def operating_condition_from_mach_muref(
     project_length_unit: LengthType.Positive = pd.Field(
         description="The Length unit of the project."
     ),
-    temperature: TemperatureType.Positive = 288.15 * u.K,
+    temperature: AbsoluteTemperatureType = 288.15 * u.K,
     alpha: Optional[AngleType] = 0 * u.deg,
     beta: Optional[AngleType] = 0 * u.deg,
     reference_mach: Optional[pd.PositiveFloat] = None,

flow360/component/simulation/conversion.py

@@ -233,6 +233,9 @@ def get_base_thermal_conductivity():
     elif dimension == u.dimensions.temperature:
         base_temperature = get_base_temperature()
         flow360_conversion_unit_system.base_temperature = base_temperature
+        # Flow360 uses absolute temperature for scaling.
+        # So the base_delta_temperature and base_temperature can have same scaling.
+        flow360_conversion_unit_system.base_delta_temperature = base_temperature
 
     elif dimension == u.dimensions.area:
         base_length = get_base_length()

flow360/component/simulation/models/material.py

@@ -8,10 +8,10 @@
 import flow360.component.simulation.units as u
 from flow360.component.simulation.framework.base_model import Flow360BaseModel
 from flow360.component.simulation.unit_system import (
+    AbsoluteTemperatureType,
     DensityType,
     PressureType,
     SpecificHeatCapacityType,
-    TemperatureType,
     ThermalConductivityType,
     VelocityType,
     ViscosityType,
@@ -50,23 +50,23 @@ class Sutherland(Flow360BaseModel):
     reference_viscosity: ViscosityType.NonNegative = pd.Field(
         description="The reference dynamic viscosity at the reference temperature."
     )
-    reference_temperature: TemperatureType.Positive = pd.Field(
+    reference_temperature: AbsoluteTemperatureType = pd.Field(
         description="The reference temperature associated with the reference viscosity."
     )
-    effective_temperature: TemperatureType.Positive = pd.Field(
+    effective_temperature: AbsoluteTemperatureType = pd.Field(
         description="The effective temperature constant used in Sutherland's formula."
     )
 
     @pd.validate_call
     def get_dynamic_viscosity(
-        self, temperature: TemperatureType.Positive
+        self, temperature: AbsoluteTemperatureType
     ) -> ViscosityType.NonNegative:
         """
         Calculates the dynamic viscosity at a given temperature using Sutherland's law.
 
         Parameters
         ----------
-        temperature : TemperatureType.Positive
+        temperature : AbsoluteTemperatureType
             The temperature at which to calculate the dynamic viscosity.
 
         Returns
@@ -154,7 +154,7 @@ def prandtl_number(self) -> pd.PositiveFloat:
 
     @pd.validate_call
     def get_pressure(
-        self, density: DensityType.Positive, temperature: TemperatureType.Positive
+        self, density: DensityType.Positive, temperature: AbsoluteTemperatureType
     ) -> PressureType.Positive:
         """
         Calculates the pressure of air using the ideal gas law.
@@ -163,7 +163,7 @@ def get_pressure(
         ----------
         density : DensityType.Positive
             The density of the air.
-        temperature : TemperatureType.Positive
+        temperature : AbsoluteTemperatureType
             The temperature of the air.
 
         Returns
@@ -174,13 +174,13 @@ def get_pressure(
         return density * self.gas_constant * temperature
 
     @pd.validate_call
-    def get_speed_of_sound(self, temperature: TemperatureType.Positive) -> VelocityType.Positive:
+    def get_speed_of_sound(self, temperature: AbsoluteTemperatureType) -> VelocityType.Positive:
         """
         Calculates the speed of sound in air at a given temperature.
 
         Parameters
         ----------
-        temperature : TemperatureType.Positive
+        temperature : AbsoluteTemperatureType
             The temperature at which to calculate the speed of sound.
 
         Returns
@@ -192,14 +192,14 @@ def get_speed_of_sound(self, temperature: TemperatureType.Positive) -> VelocityT
 
     @pd.validate_call
     def get_dynamic_viscosity(
-        self, temperature: TemperatureType.Positive
+        self, temperature: AbsoluteTemperatureType
     ) -> ViscosityType.NonNegative:
         """
         Calculates the dynamic viscosity of air at a given temperature.
 
         Parameters
         ----------
-        temperature : TemperatureType.Positive
+        temperature : AbsoluteTemperatureType
             The temperature at which to calculate the dynamic viscosity.
 
         Returns

flow360/component/simulation/models/surface_models.py

@@ -28,10 +28,10 @@
     SurfacePair,
 )
 from flow360.component.simulation.unit_system import (
+    AbsoluteTemperatureType,
     HeatFluxType,
     MassFlowRateType,
     PressureType,
-    TemperatureType,
 )
 
 # pylint: disable=fixme
@@ -89,7 +89,7 @@ class Temperature(SingleAttributeModel):
 
     type_name: Literal["Temperature"] = pd.Field("Temperature", frozen=True)
     # pylint: disable=no-member
-    value: Union[StringExpression, TemperatureType.Positive] = pd.Field(
+    value: Union[StringExpression, AbsoluteTemperatureType] = pd.Field(
         description="The temperature value."
     )
 
@@ -373,7 +373,7 @@ class Inflow(BoundaryBaseWithTurbulenceQuantities):
     name: Optional[str] = pd.Field(None, description="Name of the `Inflow` boundary condition.")
     type: Literal["Inflow"] = pd.Field("Inflow", frozen=True)
     # pylint: disable=no-member
-    total_temperature: TemperatureType.Positive = pd.Field(
+    total_temperature: AbsoluteTemperatureType = pd.Field(
         description="Specify the total temperature at the `Inflow` boundary."
     )
     velocity_direction: Optional[Axis] = pd.Field(

flow360/component/simulation/operating_condition/operating_condition.py

@@ -18,11 +18,12 @@
     StandardAtmosphereModel,
 )
 from flow360.component.simulation.unit_system import (
+    AbsoluteTemperatureType,
     AngleType,
+    DeltaTemperatureType,
     DensityType,
     LengthType,
     PressureType,
-    TemperatureType,
     VelocityType,
     ViscosityType,
 )
@@ -45,7 +46,7 @@ class ThermalStateCache(Flow360BaseModel):
 
     # pylint: disable=no-member
     altitude: Optional[LengthType] = None
-    temperature_offset: Optional[TemperatureType] = None
+    temperature_offset: Optional[DeltaTemperatureType] = None
 
 
 class ThermalState(MultiConstructorBaseModel):
@@ -65,9 +66,9 @@ class ThermalState(MultiConstructorBaseModel):
     """
 
     # pylint: disable=fixme
-    # TODO: romove frozen and throw warning if temperature/density is modified after construction from atmospheric model
+    # TODO: remove frozen and throw warning if temperature/density is modified after construction from atmospheric model
     type_name: Literal["ThermalState"] = pd.Field("ThermalState", frozen=True)
-    temperature: TemperatureType.Positive = pd.Field(
+    temperature: AbsoluteTemperatureType = pd.Field(
         288.15 * u.K, frozen=True, description="The temperature of the fluid."
     )
     density: DensityType.Positive = pd.Field(
@@ -87,7 +88,7 @@ class ThermalState(MultiConstructorBaseModel):
     def from_standard_atmosphere(
         cls,
         altitude: LengthType = 0 * u.m,
-        temperature_offset: TemperatureType = 0 * u.K,
+        temperature_offset: DeltaTemperatureType = 0 * u.K,
     ):
         """
         Constructs a :class:`ThermalState` instance from the standard atmosphere model.
@@ -96,7 +97,7 @@ def from_standard_atmosphere(
         ----------
         altitude : LengthType, optional
             The altitude at which the thermal state is calculated. Defaults to ``0 * u.m``.
-        temperature_offset : TemperatureType, optional
+        temperature_offset : DeltaTemperatureType, optional
             The temperature offset to be applied to the standard temperature at the given altitude.
             Defaults to ``0 * u.K``.
 
@@ -122,11 +123,11 @@ def from_standard_atmosphere(
         >>> thermal_state.density
         <calculated_density>
 
-        Apply a temperature offset of -5 Kelvin at 5,000 meters:
+        Apply a temperature offset of -5 Fahrenheit at 5,000 meters:
 
         >>> thermal_state = ThermalState.from_standard_atmosphere(
         ...     altitude=5000 * u.m,
-        ...     temperature_offset=-5 * u.K
+        ...     temperature_offset=-5 * u.delta_degF
         ... )
         >>> thermal_state.temperature
         <adjusted_temperature>
@@ -147,16 +148,16 @@ def from_standard_atmosphere(
     @property
     def altitude(self) -> Optional[LengthType]:
         """Return user specified altitude."""
-        if not self._cached.altitude:
+        if not self.private_attribute_input_cache.altitude:
             log.warning("Altitude not provided from input")
-        return self._cached.altitude
+        return self.private_attribute_input_cache.altitude
 
     @property
-    def temperature_offset(self) -> Optional[TemperatureType]:
+    def temperature_offset(self) -> Optional[DeltaTemperatureType]:
         """Return user specified temperature offset."""
-        if not self._cached.altitude:
+        if not self.private_attribute_input_cache.temperature_offset:
             log.warning("Temperature offset not provided from input")
-        return self._cached.temperature_offset
+        return self.private_attribute_input_cache.temperature_offset
 
     @property
     def speed_of_sound(self) -> VelocityType.Positive:
@@ -410,7 +411,7 @@ def operating_condition_from_mach_reynolds(
     project_length_unit: LengthType.Positive = pd.Field(
         description="The Length unit of the project."
     ),
-    temperature: TemperatureType.Positive = 288.15 * u.K,
+    temperature: AbsoluteTemperatureType = 288.15 * u.K,
     alpha: Optional[AngleType] = 0 * u.deg,
     beta: Optional[AngleType] = 0 * u.deg,
     reference_mach: Optional[pd.PositiveFloat] = None,
@@ -430,7 +431,7 @@ def operating_condition_from_mach_reynolds(
         Freestream Reynolds number defined with mesh unit (must be positive).
     project_length_unit: LengthType.Positive
         Project length unit.
-    temperature : TemperatureType.Positive, optional
+    temperature : AbsoluteTemperatureType, optional
         Freestream static temperature (must be a positive temperature value). Default is 288.15 Kelvin.
     alpha : AngleType, optional
         Angle of attack. Default is 0 degrees.