Fluid Film Boiling Models Reference

In a fluid film simulation, the Habchi Boiling model and the Rohsenow Boiling model are used to model the heat transfer rates from the film and predict the wall heat flux due to boiling.


Theory	See Boiling.
Model Names	Habchi Boiling Rohsenow Boiling
Provided By	[phase interaction] > Models > Boiling Model
Example Node Path	Continua > Physics 1 > Models > Multiphase Interaction > Phase Interactions > [phase interaction] > Models > Habchi Boiling
	Continua > Physics 1 > Models > Multiphase Interaction > Phase Interactions > [phase interaction] > Models > Rohsenow Boiling
Requires	Physics continuum selections: Single phase physics continuum with Multi-Component Gas. Optional Models: Coupled Energy, Segregated Fluid Enthalpy or Segregated Fluid Temperature The Fluid Film model activated, with the fluid film phase defined as a Multi-Component Liquid. Fluid Film Coupled Energy: Coupled Temperature or Fluid Film Segregated Energy: Segregated Fluid Film Temperature A Film-Physics Continuum Interaction phase interaction is required. Phase interaction selections: Optional Models: Component Mapping
Properties	Key properties are: Habchi Boiling: See Habchi Boiling Model Properties. Rohsenow Boiling: See Rohsenow Boiling Model Properties.
Activates	Model Controls (child nodes)	Rohsenow Boiling: HTCxArea Habchi Boiling: Minimum Length, Thermal Boundary Height
	Materials	Heat of Formation, Latent Heat of Vaporization, Saturation Pressure, Standard State Temperature, Critical Temperature, Critical Pressure, Leidenfrost Temperature, Nukiyama Temperature. See Material Properties.
	Field Functions	See Field Functions.

Rohsenow Boiling Model Properties

Boiling Model Parameter c_sf: Characterizes the fluid wall interface. $c_{s f}$ in Eqn. (2802).
n: The Prandtl Number Exponent. $n$ in Eqn. (2802).
Boiling Model Parameter c_s: Parameter that is used to compute the wall heat flux. $c_{s}$ in Eqn. (2806).
Constant of Critical Heat Flux: $c_{m a x}$ in Eqn. (2803).
Constant of Minimal Heat Flux: $c_{m i n}$ in Eqn. (2804).
Wall Boiling Evaporation Factor c_e: The wall boiling evaporation $c_{e}$ factor that determines how much of the boiling heat flux generates vapor. See Eqn. (2807).

Habchi Boiling Model Properties

Dry Area Fraction: The dry area fraction coefficient which sets the strength of the boiling rate through the vapor cushion. This value is $β_{2}$ in Eqn. (2818).
Under-Relaxation Factor: The heat flux under-relaxation factor.

HTCxArea

The HTCxArea node applies to Rohsenow Boiling.

The HTCxArea node represents the heat transfer coefficient ( $W / m^{2} K$ ) between the vapor bubbles and the surrounding liquid, which is multiplied by the specific contact area (contact area per unit volume, $m^{2} / m^{3}$ ) between the two.

Minimum Length

Available when using the Habchi Boiling model.

Sets the method for calculating the minimum contact lines length density

k_{c l l d}^{\min}

in Eqn. (2822).

Method	Corresponding Method Properties
Habchi Computes the minimum length $k_{c l l d}^{\min}$ with the Habchi method according to Eqn. (2823).	Surface Roughness Specifies $R_{u}$ in Eqn. (2823) Roughness Prefactor Specifies $k_{R u 1}$ in Eqn. (2823) Roughness Power Exponent Specifies $k_{R u 2}$ in Eqn. (2823)
Constant, Field Function	Specifies $k_{c l l d}^{\min}$ as a scalar value.
User Code	Function Specifies $k_{c l l d}^{\min}$ as a user-defined function.

Method

Corresponding Method Properties

Habchi

Computes the minimum length $k_{c l l d}^{\min}$ with the Habchi method according to Eqn. (2823).

Surface Roughness: Specifies $R_{u}$ in Eqn. (2823)

Roughness Prefactor: Specifies $k_{R u 1}$ in Eqn. (2823)

Roughness Power Exponent: Specifies $k_{R u 2}$ in Eqn. (2823)

Constant, Field Function

Specifies

k_{c l l d}^{\min}

as a scalar value.

User Code

Function: Specifies $k_{c l l d}^{\min}$ as a user-defined function.

Thermal Boundary Height

Available when using the Habchi Boiling model.

Sets the method for calculating the thermal boundary height

δ_{t h}

in Eqn. (2812) .

Method	Corresponding Method Properties
Evaporation Computes the thermal boundary height with the evaporation method. This method estimates the value of $δ_{t h}$ based on the maximum evaporation rate.	Maximum Evaporation Rate Specifies the maximum evaporation rate, $\dot{m_{C H F}}$ at critical heat ﬂux, or Nukiyama temperature. This is $\dot{m_{C H F}}$ in Eqn. (2813).
Constant, Field Function	Specifies $δ_{t h}$ as a scalar value.
User Code	Function Specifies $δ_{t h}$ as a user-defined function.

Material Properties

These material properties can be set for each for each component of film multi-component phases:

Heat of Formation

The heat that is evolved when 1 kilogram of the material is formed from its elements in their respective standard states [J/kg]. See Using the Heat of Formation.

Latent Heat of Vaporization

Available at the component level for multi-component phases.

Method	Corresponding Method Node
Enthalpy Difference	Enthalpy Difference This node provides no properties. See Using the Enthalpy Difference Method for Latent Heat of Vaporization.

For Simcenter STAR-CCM+ In-cylinder with Fluid Film simulations this property can be specified using a constant scalar profile, field function, Polynomial in T, or Table(T) method.

Saturation Pressure

The saturation pressure $p_{s a t}$ is the pressure of each vapor component when in equilibrium with the corresponding liquid component. This value is required for each liquid component, it can be specified as a Field Function, Polynomial in T, Table (T) or one of the following:

Method	Corresponding Method Node
Antoine Equation	Antoine Equation Defines the saturation pressure using the Antoine equation. See 使用安托因方程.
Wagner Equation	Wagner Equation Defines the saturation pressure using the Wagner equation. See 使用瓦格纳方程.

Method

Corresponding Method Node

Antoine Equation

Defines the saturation pressure using the Antoine equation. See 使用安托因方程.

Wagner Equation

Defines the saturation pressure using the Wagner equation. See 使用瓦格纳方程.

Standard State Temperature

The temperature at which the standard state of the material is defined. See 使用标准状态温度.

Critical Temperature: The temperature above which the material cannot be liquefied, regardless of the pressure that is applied. This value is required for each liquid component.
Critical Pressure: The pressure above which liquid and gas cannot coexist at any temperature. This value is required for each liquid component.

These material properties can be set for each fluid film multi-component phase:

Leidenfrost Temperature

The temperature at which the Leidenfrost effect appears. This effect creates a vapor barrier between liquid and solid phases which reduces heat transfer and adhesion. See 使用莱登弗洛斯特温度.

Nukiyama Temperature

Sets the Nukiyama temperature $T_{N}$ also known as the critical heat flux temperature $T_{c r}$ in Eqn. (2825). This is the temperature at which a liquid begins to boil and produces vapor bubbles. The Nukiyama temperature is required for each multi-component liquid.

Method	Corresponding Material Properties
Estimated Estimates the Nukiyama temperature to be halfway between the film saturation temperature and the Leidenfrost temperature according to Eqn. (2826).	None.
Habchi Use this method if you are expecting pressure variations in your simulation.	Activates the following material properties for each multi-component fluid film phase: Critical Temperature Specifies the highest of the critical temperatures of the liquid components. This is $T_{c}$ in Eqn. (2825). Saturation Temperature $T_{s a t}$ in Eqn. (2825). Normal Boiling Temperature The boiling temperature at standard temperature and pressure conditions. This is $T_{b}$ in Eqn. (2825). Normal Nukiyama Temperature The Nukiyama temperature at standard temperature and pressure conditions.

Method

Corresponding Material Properties

Estimated

Estimates the Nukiyama temperature to be halfway between the film saturation temperature and the Leidenfrost temperature according to Eqn. (2826).

None.

Habchi

Use this method if you are expecting pressure variations in your simulation.

Activates the following material properties for each multi-component fluid film phase:

Critical Temperature: Specifies the highest of the critical temperatures of the liquid components. This is $T_{c}$ in Eqn. (2825).

Saturation Temperature: $T_{s a t}$ in Eqn. (2825).

Normal Boiling Temperature: The boiling temperature at standard temperature and pressure conditions. This is $T_{b}$ in Eqn. (2825).

Normal Nukiyama Temperature: The Nukiyama temperature at standard temperature and pressure conditions.

Field Functions

The following field functions are made available when the Boiling Models are activated. These field function are available only on the liquid side.

Film Boiling Latent Heat: The latent heat of phase transfer due to boiling (J/kg).

Film Boiling Latent Heat Flux: The total power (W/m²) that is spent during the phase change due to wall boiling.

Film Boiling Mass Fraction of [component]: The latent heat of phase transfer due to boiling (J/kg).

Film Boiling Rate of [component]: The evaporation rate due to wall boiling (kg/m²-s) for every interacting component.

Film Boiling Temperature: The boiling temperature (K) of the liquid mixture.

Film Bulk Boiling Latent Heat Flux: The total power (W/m²) that is spent during the phase change due to boiling in film cells.

Film Bulk Boiling Rate: The evaporation rate due to boiling inside the film cell (kg/m²-s) for every interacting component.

Wall Boiling Heat Flux of [phase interaction]: The total power (W/m²) that is spent during the phase change due to wall boiling for the phase interaction.

Nukiyama Temperature: The Nukiyama temperature obtained from $T_{c r}$ in Eqn. (2825).