Thermal-flow functions in expressions

The following table lists the thermal-flow functions that are supported for use in CAE expressions. In the table, the following applies:

• s denotes a character string that stores the name of available options or of a point.

• v denotes a numerical value for a physical quantity such as temperature or pressure.

• i denotes the integer identification number of a stream, void, convecting zone, additional fluid material index, or of other parameters.

Tip:

To define a point, choose Menu→Insert→Model Preparation→Point. To name a point, choose Menu→Edit→Properties.

These functions apply only to duct flow modeling. The thermal solver evaluates them at run time for each element in the boundary condition selection.

Thermal-flow functions

Function	Description	Comments
ABS2REL(v1,v2,v3,v4,i,v5)	Returns the relative temperature of a fluid at a given absolute temperature, radius, rotational speed, and fluid swirl velocity.	“v1” is the absolute temperature, “v2” is the radius, “v3” is the angular velocity, “v4” is the fluid swirl velocity, “v5” is the fluid pressure, and “i” is the additional fluid material index defined in the specified multiple fluid material. All arguments are optional. When arguments are not specified, the thermal solver assigns the values from the context. See Total temperature effects for more information.
ABS2REL_SR(v1,v2,v3,v4,i,v5)	Returns the relative temperature of a fluid at a given absolute temperature, radius, rotational speed, and fluid swirl ratio.	”v1” is the absolute temperature, “v2” is the radius, “v3” is the angular velocity, “v4” is the fluid swirl ratio, “v5” is the fluid pressure, and “i” is the additional fluid material index defined in the specified multiple fluid material. All arguments are optional. When arguments are not specified, the thermal solver assigns the values from the context. See Total temperature effects for more information.
CHRS(i)	Returns the convective heat flux for the stream.	“i” is the boundary condition ID of the stream.
CHRV(i)	Returns the convective heat flux for the void.	“i” is the boundary condition ID of the void.
CHRZ(i)	Returns the convective heat flux for the zone.	“i” is the boundary condition ID of the zone.
CONDFL(v1,i,v2)	Returns the thermal conductivity of a fluid at a given temperature.	“v1” is the temperature, “v2” is the pressure, and “i” is the additional fluid material index defined in the specified multiple fluid material. The arguments “i” and “v2” are optional. You specify CONDFL in a Thermal Convecting Zone, Thermal Stream, or Thermal Void load.
DENSFL(v1,v2,i)	Returns the density of a fluid at a given temperature and pressure.	“v1” is the temperature, “v2” is the pressure, and “i” is the additional fluid material index defined in the specified multiple fluid material. All arguments are optional. When arguments are not specified, the thermal solver assigns the values from the context. You specify DENSFL in a Thermal Convecting Zone, Thermal Stream, or Thermal Void load.
DMO(i)	Returns the duct mass flow.	“i” is the label ID value of the duct, specified by the Duct Label type of the Duct Boundary Condition simulation object.
DPO(i)	Returns the duct outlet pressure.	“i” is the label ID value of the duct, specified by the Duct Label type of the Duct Boundary Condition simulation object.
DTO(i)	Returns the duct outlet temperature.	“i” is the label ID value of the duct, specified by the Duct Label type of the Duct Boundary Condition simulation object.
DUCTAREALOAD(v)	Distributes the specified heat load to duct elements according to its convection area.	“v” is the total heat load to be distributed. You specify DUCTAREALOAD in the magnitude of a Heat Load boundary condition when the selection is a whole duct or a branch. The thermal solver assigns the following heat load to each duct element: v·Ae/AT where Ae is the convection area of the duct element, and AT is the total convection area of the duct selection.
DUCTSPECFL(v1,i,v2)	Returns the constant pressure specific heat of a fluid at a given temperature.	“v1” is the temperature, “v2” is the pressure, and “i” is the additional fluid material index defined in the specified multiple fluid material. The arguments “i” and “v2” are optional. You specify DUCTSPECFL in the magnitude of a Temperature constraint when the selection is a whole duct or a branch.
ENTHFL(v1,i,v2)	Returns the specific enthalpy of a fluid at a given temperature.	“v1” is the temperature, “v2” is the pressure, and “i” is the additional fluid material index defined in the specified multiple fluid material. The arguments “i” and “v2” are optional. You specify ENTHFL in a Thermal Convecting Zone, Thermal Stream, or Thermal Void load.
GAMMAFL(v1,i,v2)	Returns the specific heat ratio of a fluid at a given temperature.	“v1” is the temperature, “v2” is the pressure, and “i” is the additional fluid material index defined in the specified multiple fluid material. The arguments “i” and “v2” are optional. You specify GAMMAFL in a Thermal Convecting Zone, Thermal Stream, or Thermal Void load.
HTCFORCE(v1, s, v2, v3, i)	Returns the heat transfer coefficient for the specified forced convection correlation.	“v1” is the hydraulic radius of the 1D duct network, “v2” is the characteristic length, “v3” is the fluid velocity, “i” is the integer number denoting the plate convection side, and “s” is the correlation type. The arguments “v2”, “v3”, and “i” are optional.The following correlation type options, “s”, are supported in the Correlation Type box:PLATEModels convective heat transfer between the fluid in a duct network and a plate in a fluid free stream. This correlation matches the Flat Plate in Free Stream correlation type. If you do not provide the characteristic length value in the optional argument “v2”, the thermal solver computes the characteristic length as the distance from the first upstream 1D network element to the 1D network element where the computation is taking place.PLATE_ENVModels forced convection from a plate oriented such that the flow passes along one surface, or along both surfaces. This correlation matches the Plate Aligned With Free Stream correlation type.You need to provide the plate convection side in the optional argument “i”. 1 indicates that the thermal solver returns the top side heat transfer coefficient, 2 indicates that it returns the bottom side heat transfer coefficient, and 3 indicates that it returns the sum of both the top and bottom side heat transfer coefficients.Note: For two-layer shells and multi-layer shells, the thermal solver only computes and returns the top side heat transfer coefficient regardless of the specified convection side value. If you do not provide the characteristic length value in the optional argument “v2”, the thermal solver computes the characteristic length as the length of the plate in the direction of the flow.DUCTModels convective heat transfer between the fluid in a duct network and the walls of the duct, using standard correlations for forced convection in a 1D flow system with a developing boundary layer. This correlation matches the Duct Developing Flow correlation type. If you do not provide the characteristic length value in the optional argument “v2”, the thermal solver computes the characteristic length as the distance from the first upstream 1D network element to the 1D network element where the computation is taking place.DUCT_FULLModels convective heat transfer between the fluid in a duct network and the walls of the duct, using standard correlations for forced convection in a 1D flow system with a fully developed boundary layer. This correlation matches the Duct Fully Developed Flow correlation type.This correlation does not need a characteristic length.All correlation types are from the Forced Convection Coupling type of the Thermal Coupling - Convection simulation object except for the Plate Aligned With Free Stream type, which is from the Forced Convection to Environment type of the Convection to Environment constraint.For more information, see Forced convection correlations.
HTCFREE(s1, s2,v1, v2)	Returns the heat transfer for the specified free convection correlation.	“s1” is the correlation type, “s2” is the convection side, “v1” is the characteristic length, and “v2” is the perimeter. The arguments “v1” and “v2” are optional.The following correlation type options, “s1”, are supported in the Correlation Type box:HORIZONTALModels natural convection from a horizontal plate. This correlation matches the Horizontal Plate correlation type.If you do not provide the characteristic length value in the optional argument “v1”, the thermal solver computes the characteristic length as the plate area divided by the specified perimeter. You specify the perimeter value, p, in the optional arguments box as follows: 0,p.INCLINEDModels natural convection from an inclined plate. This correlation matches the Inclined Plate correlation type.If you do not provide the characteristic length value in the optional argument “v1”, the thermal solver computes the characteristic length as the length of the line formed when the gravity vector is projected onto the plate.These correlations match the correlations from the Free Convection to Environment type of the Convection to Environment constraint and the Free Convection Coupling type of the Thermal Coupling - Convection simulation object.The following convection side options, “s2”, are supported in the Convection Side box:TOPReturns the top side heat transfer coefficient.BOTTOMReturns the bottom side heat transfer coefficient.BOTHReturns the sum of both the top and bottom side heat transfer coefficients.Note: For two-layer shells and multi-layer shells, the thermal solver only computes and returns the top side heat transfer coefficient regardless of the specified convection side value.For more information, see Free convection correlations.
MF(s)	Returns the local mass flow at the input point.	“s” refers to the point name, the string constant name of a point.
MIX(i1,i2,i3,.....,i10)	Returns the temperature from mixing two or more streams.	“i1” to “i10” are the boundary condition ID of the streams. MIX is applicable to up to ten streams.
MMIX(i1,i2,i3,.....,i10)	Returns the mass flow rate from mixing two or more streams.	“i1” to “i10” are the boundary condition ID of the streams. MMIX is applicable to up to ten streams.
ONEOF(v1,v2,v3,.....,v10)	Returns the first value that is defined from two or more arguments.	“v1” through “v10” are arguments that evaluate to a numerical value. “v1” and “v2” are required. Other arguments are optional. For the thermal solver, undefined values are real values equal to or less than –1.33E33.When the expression system evaluates the ONEOF function, it evaluates the value for the first argument.If the first argument returns a value greater than –1.33E33, the ONEOF function assumes the value of the first argument.If the first argument returns a value of –1.33E33 or less, the ONEOF function evaluates the value for the second argument.If the second argument returns a value greater than –1.33E33, the ONEOF function assumes the value of the second argument.If the second argument returns a value of –1.33E33 or less, the ONEOF function evaluates the value for the third argument, and so on. If none of the arguments of the ONEOF function are greater than –1.33E33, the software issues an error message.
PWR(i)	Returns power input (heat load) from feeding stream i into the void where this function is specified.	“i” is the boundary condition ID of the stream.
PWRV(v1,i)	Returns power input (heat load) from feeding void i into the void where this function is specified.	“v1” is the mass flow rate from one void to another and “i” is the boundary condition ID of the void.
RE(v1,v2,v3,v4,i)	Returns Reynold’s number for a flow over a rotating body.	“v1” is the temperature, “v2” is the radius, “v3” is the angular velocity, “v4” is the pressure, and “i” is the additional fluid material index defined in the specified multiple fluid material. All arguments are optional. When arguments are not specified, the thermal solver assigns the values from the context.
REL2ABS(v1,v2,v3,v4,i,v5)	Returns the absolute temperature of a fluid at a given relative temperature, radius, rotational speed, and fluid swirl velocity.	”v1” is the temperature, “v2” is the radius, “v3” is the angular velocity, “v4” is the fluid swirl velocity, “v5” is the fluid pressure, and “i” is the additional fluid material index defined in the specified multiple fluid material. All arguments are optional. When arguments are not specified, the thermal solver assigns the values from the context. See Total temperature effects for more information.
REL2ABS_SR(v1,v2,v3,v4,i,v5)	Returns the absolute temperature of a fluid at a given relative temperature, radius, rotational speed, and fluid swirl ratio.	”v1” is the temperature, “v2” is the radius, “v3” is the angular velocity, “v4” is the fluid swirl ratio, “v5” is the fluid pressure, and “i” is the additional fluid material index defined in the specified multiple fluid material. All arguments are optional. When arguments are not specified, the thermal solver assigns the values from the context. See Total temperature effects for more information.
REL2REL(v1,v2,v3,v4,v5,v6,i,v7)	Returns the relative temperature of a fluid at a given relative temperature, radius, rotational speed, and fluid swirl velocity for another rotational speed and fluid swirl velocity.	”v1” is the relative total temperature, “v2” is the angular velocity of the input position, “v3” is the fluid swirl velocity of the input position, “v4” is the angular velocity of the output position, “v5” is the fluid swirl velocity of the output position, “v6” is the radius, “v7” is the fluid pressure, and “i” is the additional fluid material index defined in the specified multiple fluid material. Arguments “v4”, “v5”, “v6”, “v7”, and “i” are optional. When arguments are not specified, the thermal solver assigns the values from the context. See Total temperature effects for more information.
REL2REL_SR(v1,v2,v3,v4,v5,v6,i,v7)	Returns the relative temperature of a fluid at a given relative temperature, radius, rotational speed, and fluid swirl ratio for another rotational speed and fluid swirl ratio.	”v1” is the relative total temperature, “v2” is the angular velocity of the input position, “v3” is the fluid swirl ratio of the input position, “v4” is the angular velocity of the output position, “v5” is the fluid swirl ratio of the output position, “v6” is the radius, “v7” is the fluid pressure, and “i” is the additional fluid material index defined in the specified multiple fluid material. Arguments “v4”, “v5”, “v6”, “v7”, and “i” are optional. When arguments are not specified, the thermal solver assigns the values from the context. See Total temperature effects for more information.
SA(i)	Returns the convecting area of a stream.	“i” is the boundary condition ID of the stream.
SA2(i1,i2)	Returns the convecting area of one side of a two-sided stream.	“i1” is the boundary condition ID of the stream, “i2” is 1 to represent side A of the stream, or 2 to represent side B. Argument “i2” is optional. When you omit “i2”, SA2 behaves the same as the SA function and returns the total convecting area of the two-sided stream.
SAC(i)	Returns corrected convecting area for the stream.	“i” is the boundary condition ID of the stream.
SAC2(i1,i2)	Returns the corrected convecting area of one side of a two-sided stream.	“i1” is the boundary condition ID of the stream and “i2” is the side of the stream. 1 represents side A and 2 represents side B. The “i2” argument is optional. When you omit “i2”, SAC2 behaves the same as the SAC function and returns the total corrected convecting area of the two-sided stream.
SMO(i)	Returns the outlet nodal mass flow that is defined on the stream elements.	“i” is the boundary condition ID of the stream.
SP(i)	Returns the maximum elemental pressure of the stream.	“i” is the boundary condition ID of the stream.
SPECFL(v1,i,v2)	Returns the constant pressure specific heat of a fluid at a given temperature.	“v1” is the temperature, “v2” is the pressure, and “i” is the additional fluid material index defined in the specified multiple fluid material. The arguments “i” and “v2” are optional. You specify SPECFL in a Thermal Convecting Zone, Thermal Stream, or Thermal Void load.
SSV(i)	Returns the outlet fluid swirl velocity of the stream.	“i” is the boundary condition ID of the stream.
STI(i)	Returns the stream total absolute or relative inlet nodal temperature.	“i” is the boundary condition ID of the stream.
STMO(i)	Returns the outlet elemental metal (solid) temperature of the stream.	“i” is the boundary condition ID of the stream.
STO(i)	Returns the stream total absolute or relative outlet nodal temperature.	“i” is the boundary condition ID of the stream.
TEMPF(s)	Returns the local temperature of the fluid at the input point.	“s” refers to the point name, the string constant name of a point.
THRS(i)	Returns the total convective heat flux and the heat pickup for the stream.	“i” is the boundary condition ID of the stream.
THRV(i)	Returns the total convective heat flux and the heat pickup for the void.	“i” is the boundary condition ID of the void.
THRZ(i)	Returns the total convective heat flux and the heat pickup for the zone.	“i” is the boundary condition ID of the zone.
UG_PR(v1,v2,v3,...)	Uses the value for the first argument in the formula for the expression and writes the argument values to the solver monitor and solver log file.	“v1”, “v2”, “v3”, etc. are arguments that evaluate to a numerical value. “v1” is required. Other arguments are optional.If the value of the last argument does not change for the selected elements, then the thermal solver writes the printout only once, for the first INPF element.Use this function as a debug tool.Example: If you want to obtain the values for the density of the fluid and the temperature and pressure that the software uses to evaluate the fluid density, specify:ug_pr(densfl(temperature1,pressure1,3),temperature1,pressure1)where densfl is the evaluated fluid density, temperature1 and pressure1 are expressions for temperature and pressure, respectively, and 3 is the fluid material index.Then the software uses the value for densfl(temperature1,pressure1,3) to evaluate the formula for the expression and writes the values for the fluid density, temperature, and pressure for each selected boundary condition element to the solver monitor and solver log file.If pressure1 is the same value for all selected elements, then the software writes the values for the fluid density, temperature, and pressure only for the first boundary condition element listed in INPF.
VA(i1,i2)	Returns the convecting area of a void.	“i1” is the boundary condition ID of the thermal void and “i2” is the index of the void region of interest. “i1” is required. “i2” is optional. When “i2” is specified, the function returns the convecting area of the void with respect to the specified region. When “i2” is not specified, the function returns the sum of all region areas.
VAC(i)	Returns corrected convecting area for the void.	“i” is the boundary condition ID of the void.
VISCFL(v1,i,v2)	Returns the viscosity of a fluid at a given temperature.	“v1” is the temperature, “v2” is the pressure, and “i” is the additional fluid material index defined in the specified multiple fluid material. The arguments “i” and “v2” are optional. You specify VISCFL in a Thermal Convecting Zone, Thermal Stream, or Thermal Void load.
VP(i1,i2)	Returns the maximum elemental pressure of the void.	“i1” is the boundary condition ID of the thermal void and “i2” is the index of the void region of interest. “i1” is required. “i2” is optional. When “i2” is specified, the function returns the maximum elemental pressure of the void with respect to the specified region. When “i2” is not specified, the function returns the maximum elemental pressure of the void for all void regions.
VSV(i1,i2)	Returns the maximum elemental swirl velocity of the void.	“i1” is the boundary condition ID of the thermal void and “i2” is the index of the void region of interest. “i1” is required. “i2” is optional. When “i2” is specified, the function returns the maximum elemental swirl velocity of the void with respect to the specified region. When “i2” is not specified, the function returns the maximum elemental swirl velocity of the void for all void regions.
VT(i1,i2)	Returns the total absolute or relative maximum elemental temperature of the void.	“i1” is the boundary condition ID of the thermal void and “i2” is the index of the void region of interest. “i1” is required. “i2” is optional. When “i2” is specified, the function returns the maximum elemental temperature of the void with respect to the specified region. When “i2” is not specified, the function returns the maximum elemental temperature of the void for all void regions.
ZA(i)	Returns the convecting zone area.	“i” is the boundary condition ID of the convecting zone.
ZP(i)	Returns the maximum elemental pressure of the convecting zone.	“i” is the boundary condition ID of the convecting zone.
ZSV(i)	Returns the maximum elemental swirl velocity of the convecting zone.	“i” is the boundary condition ID of the convecting zone.
ZT(i)	Returns the total absolute or relative maximum elemental temperature of the convecting zone.	“i” is the boundary condition ID of the convecting zone.
ZAC(i)	Returns the corrected convecting area for the zone.	“i” is the boundary condition ID of the zone.

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