Coupled Energy Model Reference


Theory	See Coupled Flow Solver.
Provided By	[physics continuum] > Models > Optional Models
Example Node Path	Continua > Physics 1 > Models > Coupled Energy
Requires	Material: one of Gas, Liquid, Multi-Component Gas, Multi-Component Liquid Reaction Regime (for multi-component materials): any Flow: Coupled Flow
Properties	Enthalpy Formulation Flow Boundary Diffusion See Coupled Energy Properties.
Activates	Physics Models	Optional Models: Boiling, Circumferential Heat Flux Averaging, Thermal Comfort, Thin Film
	Material Properties	Thermal Conductivity See Material Properties.
	Reference Values	Maximum Allowable Temperature Minimum Allowable Temperature See Reference Values.
	Initial Conditions	Static Temperature See Initial Conditions.
	Boundary Inputs	See Boundary Settings.
	Region Inputs	See Region Settings.
	Interface Inputs	See Interface Settings.
	Monitors	Energy
	Reports Options	Heat Exchanger (Dual Stream) Heat Exchanger (Single Stream) Heat Transfer Isentropic Efficiency Temperature Correction See Reports.
	Field Functions	Boundary Advection Heat Flux Boundary Advection Heat Transfer Boundary Conduction Heat Flux Boundary Conduction Heat Transfer Boundary Heat Flux Boundary Heat Flux on External Side Boundary Heat Flux Radiation Coefficient Boundary Heat Transfer Effective Conductivity Energy Residual External Ambient Temperature External Heat Transfer Coefficient Heat Exchanger Energy Source Heat Exchanger Temperature Difference Heat Exchanger Temperature Jump Heat Transfer Coefficient Internal Wall Heat Flux Coefficient, A Internal Wall Heat Flux Coefficient, B Internal Wall Heat Flux Coefficient, C Internal Wall Heat Flux Coefficient, D Local Heat Transfer Coefficient Local Heat Transfer Reference Temperature Net Wall Heat Flux Coefficient, A Net Wall Heat Flux Coefficient, B Net Wall Heat Flux Coefficient, C Net Wall Heat Flux Coefficient, D Nusselt Number Porous Solid Conductivity Relative Total Enthalpy Relative Total Temperature Rothalpy Specific Heat Specified Y+ Heat Transfer Coefficient Specified Y+ Heat Transfer Reference Temperature Temperature Temperature Coefficient Temperature on External Side Thermal Conductivity Thermal Resistance Time Averaged Boundary Heat Flux Total Energy Total Enthalpy Total Temperature See Heat Transfer Field Functions Reference.

Coupled Energy Properties

Enthalpy Formulation: When On, uses enthalpy as the dependent variable when solving the energy conservation equation. When Off, uses temperature as the dependent variable.
Flow Boundary Diffusion: When On, activates the flow-boundary diffusion fluxes (or viscous fluxes for flow models). See Eqn. (897).

Material Properties

Thermal Conductivity

Specifies the thermal conductivity

k

of the fluid.


Method	Corresponding Method Node
Constant	Constant Specifies the thermal conductivity using a scalar profile value.
Field Function	Field Function Specifies the thermal conductivity using a scalar field function.
Kinetic Theory Uses the Kinetic Theory Method for Thermal Conductivity.	Kinetic Theory This node provides no properties. Selecting the Kinetic Theory method adds the following material properties: Dipole Momentum A measure of polarity of a covalent bond in the molecule (always given in Debye). Lennard-Jones Characteristic Length (Angstrom) $σ$ in Eqn. (844). For multi-component gases, this value is calculated as a mass-weighted average of the gas components. If you adjust this value, make sure that it realistically represents values given in literature for the specific material. Lennard-Jones Energy The potential energy of attraction (given in K). If you adjust this value, make sure that it realistically represents values given in literature for the specific material. Molecule Type Describes the molecular structure using the following values: 0: atom 1: linear molecule 2: non-linear molecule Rotation The rotational relaxation collision number (non-dimensional).
Non-Equilibrium Kinetic Theory (if the Thermal Non-Equilibrium Ideal Gas model is selected)	Non-Equilibrium Kinetic Theory This node provides no properties. Selecting the Non-Equilibrium Kinetic Theory method adds the same material properties as the Kinetic Theory method.
Polynomial in T	Polynomial in T See Using Polynomial in T.
Power Law Uses the Power Law for Thermal Conductivity.	Power Law Exposes the following properties: Reference Temperature—the reference temperature $T_{0}$ in Eqn. (133). Reference Value—the reference conductivity $k_{0}$ in Eqn. (133). Temperature Exponent—the temperature exponent $n$ in Eqn. (133).
Sutherland's Law Uses Sutherland's Law for Thermal Conductivity.	Sutherland's Law Exposes the following properties: Reference Temperature—the reference temperature $T_{0}$ in Eqn. (130). Reference Value—the reference conductivity $k_{0}$ in Eqn. (130). Sutherland Constant—the Sutherland Constant $S$ in Eqn. (130).
Table(T) Tabulates the thermal conductivity as a function of temperature.	Table(T) See Using Table(T).
Table(T,p) Tabulates the thermal conductivity as a function of temperature and pressure.	Table(T,p) See Using Table(T,p).

Reference Values

Maximum Allowable Temperature

The largest temperature value that is permitted anywhere in the continuum.

The Energy models (Coupled Energy, Coupled Solid Energy, Segregated Solid Energy, Segregated Fluid Enthalpy, Segregated Fluid Isothermal, Segregated Fluid Temperature) limit temperature corrections such that the corrected value does not exceed this maximum. If this occurs, a message is printed to the Output window.

Minimum Allowable Temperature

The smallest temperature value that is permitted anywhere in the continuum.

The Energy models (Coupled Energy, Coupled Solid Energy, Segregated Solid Energy, Segregated Fluid Enthalpy, Segregated Fluid Isothermal, Segregated Fluid Temperature) limit temperature corrections such that the corrected value does not go below this minimum. If this occurs, a message is printed to the Output window.

Initial Conditions

Static Temperature: Sets the initial static temperature in the continuum.

Boundary Settings

Note	Boundary types that do not require setting any conditions or values are not listed.

Mass Flow Inlet, Stagnation Inlet

Total Temperature: The total temperature at the boundary.

Velocity Inlet, Pressure Outlet, Free Stream

Static Temperature: The static temperature at the boundary.

Wall

Circumferential Averaging of Energy

When On, activates averaging of the heat flux between a boundary and its region with relative rotation between them—for example, a stationary boundary and a fluid in a rotating region. See Energy Averaging for Rotating Fluids with Stationary Wall Boundaries. The default is Off.

This option becomes available only when the tangential velocity of the wall boundary is different from the angular velocity of the fluid region. This velocity difference can be achieved by one of the following:

The wall boundary is associated with a reference frame different from the Region Reference Frame and the rotation vector (= rotation axis x rotation rate) between the two reference frames is different. The fluid region can rotate by defining a moving reference frame. For more information, see Reference Frames.
The wall boundary is associated with the same reference frame as the fluid region, but Tangential Velocity Specification is set to a different velocity.

This option is not compatible with the Circumferential Heat Flux Averaging model, Porous Media models, or Eulerian multiphase models except for the Volume of Fluid (VOF) model.

Thermal Specification

Allows you to determine how the energy flow across the boundary is specified.


Method	Corresponding Physics Value Nodes
Heat Flux	Heat Flux Specifies the amount of energy flowing across the boundary in W/m². A positive specified heat flux value $q$ means that heat is flowing into the domain. This is opposite to the convention that the boundary heat flux $q_{w} = q \cdot n$ is negative for an inflow of heat (due to outward pointing surface normals at boundaries). The sign of $q$ is switched at this point.
Heat Source	Heat Source Specifies a total heat source in W.
Temperature	Static Temperature Specifies the boundary temperature in K.
Adiabatic Specifies that there is no energy transfer across the boundary.	None.
Convection Specifies convection flux across the boundary in W/m².	Ambient Temperature Specifies the ambient temperature in K. Heat Transfer Coefficient Specifies the heat transfer coefficient in W/m²K.

User Wall Heat Flux Coefficient Specification

Controls whether to specify the heat flux relationship at the boundary.


Method	Corresponding Physics Value Nodes
None Leaves off this feature.	None.
Specified Activates this feature.	User Wall Heat Flux Coefficient, A The user contribution to the constant coefficient of wall heat flux $A$ . User Wall Heat Flux Coefficient, B The user contribution to the cell temperature coefficient of wall heat flux $B$ . User Wall Heat Flux Coefficient, C The user contribution to the wall temperature coefficient of wall heat flux $C$ . User Wall Heat Flux Coefficient, D The user contribution to the wall temperature coefficient of wall heat flux $D$ . The user specified coefficients are added to the internally calculated net coefficients as given by Eqn. (203).
Specified Net Activates this feature for net flux.	Sets the net boundary heat flux coefficients equal to the user specified heat flux coefficients as given by Eqn. (204). This method is available in Multiphase Segregated Flow simulations only.

Baffle Interface Boundary, Porous Baffle Interface Boundary, Contact Interface Boundary

User Wall Heat Flux Coefficient Specification: As for Wall.

Mapped Contact Interface Boundary

Static Temperature: Automatically sets the static temperature for use with the temperature thermal boundary condition. Uses the Mapped Temperature method.; This value node becomes available when the Energy Coupling Option at the interface is set to Explicit.

Region Settings

The following values and conditions apply to fluid and porous regions:

Heat Exchanger UAL

For a Fluid-Solid Type Dual Stream Heat Exchanger, represents the local (or cell) heat exchange rate, that may either be specified as a constant or a function of the fluid properties. The specified value is added to the source term of the fluid energy equation and subtracted from the source term of the solid energy equation.

This value node becomes available when Heat Exchanger Method at the heat exchanger interface is set to Basic Dual Stream or Actual Flow Dual Stream.

Heat Exchanger Exit Temperature Specification

Allows you to specify the temperature at the outlet.

This condition node becomes available when the region condition Energy Source Option is set to Heat Exchanger.


Outlet Temperature	Corresponding Physics Value Nodes
Inferred Allows you to specify the overall heat transfer rate, while allowing Simcenter STAR-CCM+ to compute the temperature at the outlet.	Heat Exchanger Total Energy Rate Specifies the fixed rate of heat transfer from or to the device, typically measured in W. This quantity represents the total energy transfer for the heat exchanger enthalpy source.
Specified Allows you to specify the temperature at the outlet, while allowing Simcenter STAR-CCM+ to compute the overall heat transfer rate.	Target Exit Temperature Exposes the following properties: Target Outlet Temperature—specifies the target temperature at the outlet. Under-Relaxation Factor—governs the extent to which the new calculation supplants the old one as Simcenter STAR-CCM+ computes the heat transfer rate. The Heat Transfer Rate is shown as a read-only property

Energy Source Option

Specifies whether you want to enter an energy source term, and of which type. The energy source corresponds to $S_{u}$ in Eqn. (947). Unless otherwise specified, the conditions below apply to fluid, porous, and solid regions.


Energy Source Option	Corresponding Physics Value Nodes
None	None.
Volumetric Heat Source	Volumetric Heat Source Specifies a user-defined volumetric heat source in W/m³. Energy Source Pressure Derivative Represents the derivative of the energy source with respect to pressure. The derivative of the user source term is used to linearize Eqn. (947). Its value is set to zero by default. Providing a value for the derivative helps stabilize the solution when the function for the source term is a function of pressure. If the source is constant, or not a function of pressure, leave this value at zero. Energy Source Temperature Derivative Represents the linearization of the energy source with respect to temperature. The derivative of the user source term is used to linearize Eqn. (947). Its value is set to zero by default. Providing a value for the derivative helps stabilize the solution when the function for the source term is a function of temperature. If the source is constant, or not a function of temperature, leave this value at zero. Energy Source Velocity Derivative Represents the linearization of the energy source with respect to x-, y-, [z-] components of velocity. The derivative of the user source term is used to linearize Eqn. (947). Its value is set to zero by default. Providing a value for the derivative helps stabilize the solution when the energy source is a function of velocity. If the source is constant, or not a function of velocity, leave this value at zero.
Total Heat Source	Heat Source Specifies a user-defined total heat source in W. If the profile for the heat source uses field functions or user code, the relation between the heat sources for individual cells, as specified by the field function, and the heat source for the entire region is: $h_{c} = h_{t o t} V_{c} / V_{t o t}$ where: $h_{c}$ is heat source for the cell. $h_{t o t}$ is total heat source in the volume or on the surface. $V_{c}$ is the cell volume. $V_{t o t}$ is the total volume. For two-dimensional simulations, the volumes are replaced by surface areas. Energy Source Pressure Derivative As for Volumetric Heat Source. Energy Source Temperature Derivative As for Volumetric Heat Source. Energy Source Velocity Derivative As for Volumetric Heat Source.
Specific Heat Source	Specific Heat Source Specifies a user-defined total heat source in W/kg. Energy Source Temperature Derivative As for Volumetric Heat Source.
Heat Exchanger	Heat Exchanger Minimum Temperature Difference Specifies the minimum allowable temperature difference between the following: The specified heat exhanger temperature and the maximum fluid temperature for a heater (that is, when the specified Heat Exchanger Total Energy Rate is positive). The specified heat exchanger temperature and the minimum fluid temperature for a cooler (that is, when the specified Heat Exchanger Total Energy Rate is negative). Heat Exchanger Boundaries Specifies the upstream and downstream interface boundaries that the Heat Exchanger (Single Stream) report uses: Upstream Interface Boundary—the interface boundary through which fluid enters the heat exchanger region. Downstream Interface Boundary—the interface boundary through which fluid leaves the heat exchanger region. This node assumes that the heat exchanger region interfaces with two other regions. Heat Exchanger First Iteration Sets the First Heat Exchanger Iteration from which the heat exchanger enthalpy source is active and begins its contribution to the source term of the energy equation.Ideally, activate the heat exchanger source term when the flow solution is beginning to conform to its final pattern (at least in terms of direction). Conformity could typically be achieved within the first 50 iterations of the flow solver for a moderately complex geometry. Heat Exchanger Temperature Specifies the reference temperature of the heat exchanger enthalpy source. The local fluid temperature at each cell is subtracted from the reference temperature to determine the relative amount of heat that is transferred from and/or to the cell. See $T_{r e f}$ in Eqn. (225). For more information, see Using the Single Stream Heat Exhanger Option.

The following values apply to porous regions:

Solid Density: Specifies the solid density $ρ_{s o l i d}$ in Eqn. (1846). The fluid density $ρ_{f l u i d}$ in Eqn. (1846) is the density property that is specified for the fluid continuum. It is entered as a scalar profile.; This node is only available for unsteady simulations.
Solid Specific Heat: Specifies the solid specific heat $C_{p - s o l i d}$ in Eqn. (1840). It is entered as a scalar profile.; This node is only available for unsteady simulations.
Solid Thermal Conductivity: Specifies $k_{s o l i d}$ in Eqn. (1846). The fluid thermal conductivity $k_{f l u i d}$ in Eqn. (947) is extracted from the property that is specified for the fluid continuum. It is entered as a tensor profile.

Interface Settings

Note	Interface types that do not require setting any conditions or values are not listed.

Baffle Interface, Porous Baffle Interface

Baffle Thermal Option

Specifies whether the baffle conducts energy.


Baffle Thermal Option	Corresponding Physics Value Nodes
Non-Conducting No thermal conduction occurs through the baffle.	None.
Conducting Thermal conduction occurs through the baffle	Thermal Resistance The value of the resistance to conduction through the baffle. For conduction through multiple materials that vary in conductivity, you can set a Multi-Layer Resistance.

Energy Source Option

Provides energy source options for the interface.

This condition node becomes available when the Baffle Thermal Option is set to Conducting.


Option	Corresponding Physics Value Node
None Does not specify an energy source.	None.
Heat Flux	Heat Flux Specifies the amount of energy flowing across the interface in W/m².
Heat Source	Heat Source Specifies a total heat source in W.

Blower Interface

Blower Heat Generation Rate: Specifies the heat that is generated by the blower per unit time. This heat is added to the flow that exits the blower.
Fan Curve Temperature Scaling: Scales the fan performance curve using data temperature. See Specifying the Fan Curve Temperature Scaling.

Fan Interface

Fan Curve Temperature Scaling: Scales the fan performance curve using data temperature. See Specifying the Fan Curve Temperature Scaling.

Fully Developed Interface

Fully Developed Energy Option

Specifies the energy option at the interface.


Method	Corresponding Physics Value Nodes
Periodic No temperature or enthalpy discontinuity at the interface.	None.
Constant Temperature Walls This option corresponds to the situation where the walls of the periodic domains are held at constant temperatures. If the wall temperature varies, the scaling of the temperature profile is not correct and an error is incurred. Activates the `Inflow Temperature Specification` condition node	Temperature Reference Specifies the Reference Boundaries used for the reference temperature.
Constant Heat Flux Walls This option corresponds to the situation where a constant heat flux is introduced at the walls of the periodic domain. If the heat flux varies, the scaling of the temperature profile might be affected, introducing some additional error. Periodically varying heat fluxes might be acceptable, since the resulting temperature field is linear, allowing the principle of superposition to be applied. Activates the `Inflow Temperature Specification` condition node	None.

Inflow Temperature Specification

Specifies the temperature option at the interface.

This condition node becomes available when the Fully Developed Energy Option is set to Constant Temperature Walls or Constant Heat Flux Walls.


Method	Corresponding Physics Value Nodes
Bulk Mean Inflow Temperature	Bulk Inflow Temperature Specifies the bulk mean temperature at the inflow boundary.
Minimum Inflow Temperature	Minimum Inflow Temperature Specifies the lower limit of the temperature at the inflow boundary For the Constant Temperature Walls condition, this value should be smaller than the reference temperature.
Maximum Inflow Temperature	Maximum Inflow Temperature Specifies the upper limit of the temperature at the inflow boundary. For the Constant Temperature Walls condition, this value should be larger than the reference temperature.

Contact Interface

Thermal Specification

Allows you to specify the thermal conditions at the interface.


Method	Corresponding Physics Value Nodes
Conjugate Heat Transfer The temperature at the interface is determined from the heat transferred through the interface.	Contact Resistance The value of resistance to conduction through the interface. If a field function defines the value and the Ignore Boundary Values property of the field function is activated, the function is computed using data from the cell next to the boundary identified by the Boundary-0 property of the interface.
Specified Temperature The temperature at the interface is the same for both parent boundaries as specified.	Static Temperature The value of the static temperature at the interface.

Energy Source Option

Provides energy source options for the interface.


Method	Corresponding Physics Value Nodes
None	None.
Heat Flux	Heat Flux Specifies the amount of energy flowing across the interface in W/m².
Heat Source	Heat Source Specifies a total heat source in W.

Mapped Contact Interface

Energy Coupling Option

Specifies implicit or explicit coupling of the energy equation across the interface.


Method	Corresponding Physics Value Nodes
Implicit Set automatically when the interface connects two solid regions. When the interface connects a solid region with a fluid region, use this method when the time scales on both sides are similar.	Contact Resistance The value of resistance to conduction through the interface. If a field function defines the value and the Ignore Boundary Values property of the field function is activated, the function is computed using data from the cell next to the boundary identified by the Boundary-0 property of the interface.
Explicit (only available when the interface connects a solid region with a fluid region) Use this method when the time scales on both sides are very different. This method results in the mapping of thermal fields across the two interface boundaries. It applies a convection thermal boundary condition on the solid interface boundary and a temperature thermal boundary condition on the fluid interface boundary.	None.

Energy Source Option

As for Contact Interface.

This condition node is not available when the Energy Coupling Option at the interface is set to Explicit.

Heat Exchanger Interface

Heat Exchanger Method

Specifies the dual stream heat exchanger approach. See The Basic and Actual Dual Stream Heat Exchanger Options.


Option	Corresponding Physics Value Node
Inactive Does not affect the source terms of the energy equation.	None.
Basic Dual Stream	Heat Exchanger First Iteration For a fluid-fluid type heat exchanger, sets the First Heat Exchanger Iteration from which the heat exchanger is active and begins its contribution to the source term of the energy equation.
Actual Flow Dual Stream	Heat Exchanger First Iteration As for Basic Dual Stream

Heat Exchanger Data Specification

For a fluid-fluid type heat exchanger, allows you to set the heat transfer rate. See Heat Exchanger Data Specification Reference.

This condition node becomes available when Heat Exchanger Method is set to Basic Dual Stream or Actual Flow Dual Stream.

Hot Stream Inlet Temperature Specification

For a fluid-fluid type heat exchanger, allows you to set a target heat rejection rate for the heat exchanger without setting the temperature at the hot inlet. Simcenter STAR-CCM+ then predicts the temperature that is required at the inlet to sustain the heat rejection rate. See Target Heat Rejection.

This condition node becomes available when Heat Exchanger Method is set to Basic Dual Stream or Actual Flow Dual Stream.

Reports

Heat Exchanger (Dual Stream): Uses calculations with an interface between two regions. This technique involves the heat exchange between a cold fluid stream and a hot fluid stream. These streams are modeled as two different physics continua (each having different material properties). See Heat Exchanger.
Heat Exchanger (Single Stream): Uses calculations with one region. By this method, one stream is assumed to have a uniform temperature and the other stream is modeled by specifying the heat exchanger enthalpy source. See Heat Exchanger.
Heat Transfer: Reports the total heat transfer at a boundary in W. See Heat Transfer.
Isentropic Efficiency: Reports the isentropic efficiency of a process between an inlet boundary (or boundaries) and outlet boundary (or boundaries). See Isentropic Efficiency Report.
Temperature Correction: Reports the scaled correction to the temperature calculation at the end of each iteration. See Temperature Correction