BF

BF, Node, Lab, VAL1, VAL2, VAL3, VAL4, VAL5, VAL6, MESHFLAG
Defines a nodal body-force load.

SOLUTION: FE Body Loads

Node

Node to which body load applies. If Node = ALL, apply to all selected nodes (NSEL). A component name may also be substituted for Node.

Lab

Valid body load label. Load labels are listed under "Body Loads" in the input table for each element type in the Element Reference.

Discipline	Body Load Label	Label Description
Structural	TEMP	Temperature
	FREQ	Frequency (harmonic analyses only)
	FLUE	Fluence
	FPBC	Floquet periodic boundary condition
Thermal	HGEN	Heat generation rate (updated by volume changes when large-deflection effects are included (NLGEOM,ON))
Thermal	VELO	Velocity for mass transport
Magnetic	TEMP	Temperature
	VELO	Velocity or angular velocity
	MVDI	Magnetic virtual displacements flags
Electric	TEMP	Temperature
Electric	CHRGD	Charge density
Acoustic	MASS	Mass source; mass source rate; or power source in an energy diffusion solution for room acoustics
	IMPD	Impedance sheet
	SPRE	Static pressure
	TEMP	Temperature
	VELO	Velocity or acceleration
	PORT	Interior acoustics port
	FPBC	Floquet periodic boundary condition
	VMEN	Mean flow velocity
	UFOR	Force potential
	SFOR	Shear force for viscous-thermal acoustics or poroelastic acoustics
	HFLW	Volumetric heat source for viscous-thermal acoustics
Poromechanics	FSOU	Fluid flow source
Diffusion	TEMP	Temperature
	DGEN	Diffusing substance generation rate
	VELO	Transport velocity

VAL1, VAL2, VAL3, VAL4, VAL5, VAL6

Value associated with the Lab item or table name reference for tabular boundary conditions. Use only VAL1 for TEMP, FLUE, HGEN, DGEN, MVDI, CHRGD, PORT, and SPRE.

Tabular input is supported for certain labels (see Notes for details). To specify a table, enclose the table name in percent signs (%) (e.g., BF,Node,TEMP,%tabname%). Use the *DIM command to define a table.

If Lab = MASS for acoustics:

*`VAL1`*	—	Mass source with units of kg/(m³s) in a harmonic analysis or in a transient analysis solved with the velocity potential formulation; or mass source rate with units of kg/(m³s²) in a transient analysis solved with the pressure formulation; or power source with units of watts in an energy diffusion solution for room acoustics
*`VAL2`*	—	Phase angle in degrees
*`VAL3`*	—	Not used
*`VAL4`*	—	Not used
*`VAL5`*	—	Not used
*`VAL6`*	—	Not used

If Lab = VELO for acoustics (velocity components in a harmonic analysis or in a transient analysis solved with the velocity potential formulation; or acceleration components in a transient analysis solved with the pressure formulation):

*`VAL1`*	—	X component
*`VAL2`*	—	Y component
*`VAL3`*	—	Z component
*`VAL4`*	—	X-component phase angle in degrees
*`VAL5`*	—	Y-component phase angle in degrees
*`VAL6`*	—	Z-component phase angle in degrees

If Lab = VELO for electromagnetics (velocity and angular velocity components in the global Cartesian coordinate system):

*`VAL1`*	—	Velocity component in the X direction
*`VAL2`*	—	Velocity component in the Y direction
*`VAL3`*	—	Velocity component in the Z direction
*`VAL4`*	—	Angular velocity about the X axis (rad/sec)
*`VAL5`*	—	Angular velocity about the Y axis (rad/sec)
*`VAL6`*	—	Angular velocity about the Z axis (rad/sec)

If Lab = VELO for thermal (velocity components in the global Cartesian coordinate system):

*`VAL1`*	—	Mass transport velocity component in X direction
*`VAL2`*	—	Mass transport velocity component in Y direction
*`VAL3`*	—	Mass transport velocity component in Z direction
*`VAL4`*	—	Not used
*`VAL5`*	—	Not used
*`VAL6`*	—	Not used

If Lab = VELO for diffusion (transport velocity):

*`VAL1`*	—	Transport velocity component in X direction
*`VAL2`*	—	Transport velocity component in Y direction
*`VAL3`*	—	Transport velocity component in Z direction
*`VAL4`*	—	Not used
*`VAL5`*	—	Not used
*`VAL6`*	—	Not used

If Lab = IMPD:

*`VAL1`*	—	Resistance in N⋅s/m³
*`VAL2`*	—	Reactance in N⋅s/m³
*`VAL3`*	—	Not used
*`VAL4`*	—	Not used
*`VAL5`*	—	Not used
*`VAL6`*	—	Not used

If Lab = FPBC:

*`VAL1`*	—	Phase shift (product of phase constant and period in unit radian); or Floquet boundary flag (set `VAL1` = YES) for a modal analysis that solves the eigenvalues with a specified frequency (`FREQMOD` on the MODOPT command)
*`VAL2`*	—	Attenuation (product of attenuation constant and period); not used if `VAL1` = YES
*`VAL3`*	—	Not used
*`VAL4`*	—	Not used
*`VAL5`*	—	Not used
*`VAL6`*	—	Not used

If Lab = VMEN:

*`VAL1`*	—	Mean flow velocity component in the X direction
*`VAL2`*	—	Mean flow velocity component in the Y direction
*`VAL3`*	—	Mean flow velocity component in the Z direction
*`VAL4`*	—	Not used
*`VAL5`*	—	Not used
*`VAL6`*	—	Not used

If Lab = UFOR:

*`VAL1`*	—	Real part of complex force potential
*`VAL2`*	—	Imaginary part of complex force potential
*`VAL3`*	—	Not used
*`VAL4`*	—	Not used
*`VAL5`*	—	Not used
*`VAL6`*	—	Not used

If Lab = SFOR:

*`VAL1`*	—	X component of shear force for viscous-thermal acoustics or poroelastic acoustics
*`VAL2`*	—	Y component of shear force for viscous-thermal acoustics or poroelastic acoustics
*`VAL3`*	—	Z component of shear force for viscous-thermal acoustics or poroelastic acoustics
*`VAL4`*	—	X-component phase angle in degrees
*`VAL5`*	—	Y-component phase angle in degrees
*`VAL6`*	—	Z-component phase angle in degrees

If Lab = HFLW:

*`VAL1`*	—	Real part of volumetric heat source for viscous-thermal acoustics
*`VAL2`*	—	Imaginary part of volumetric heat source for viscous-thermal acoustics
*`VAL3`*	—	Not used
*`VAL4`*	—	Not used
*`VAL5`*	—	Not used
*`VAL6`*	—	Not used

MESHFLAG

Specifies how to apply nodal body-force loading on the mesh. Valid in a nonlinear adaptivity analysis when Lab = HGEN or TEMP, and Node is not a component name.

0 – Nodal body-force loading occurs on the current mesh (default).

1 – Nodal body-force loading occurs on the initial mesh for nonlinear adaptivity.

Notes

Defines a nodal body-force load (such as temperature in a structural analysis, heat generation rate in a thermal analysis, etc.). Nodal body loads default to the BFUNIF values, if they were previously specified.

Table names are valid for Lab value (VALn) inputs in these cases only:

VAL1 = %tabname% for:
temperatures (TEMP), diffusing substance generation rates (DGEN), and heat generation rates (HGEN).
VAL1 = %tabname1% and VAL2 = %tabname2% for:
mass source, mass source rate, or power source (MASS); the Floquet periodic boundary condition (FPBC); the force potential (UFOR); and the volumetric heat source (HFLW).
VAL1 = %tabname1%, VAL2 = %tabname2%, and VAL3 = %tabname3% for:
mean flow velocities (VMEN).
VAL1 = %tabname1%, VAL2 = %tabname2%, VAL3 = %tabname3%, VAL4 = %tabname4%, VAL5 = %tabname5%, and VAL6 = %tabname6% for:
velocities or accelerations (VELO); and shear force (SFOR).

The heat generation rate loads specified with the BF command are multiplied by the weighted nodal volume of each element adjacent to that node. This yields the total heat generation at that node.

In a modal analysis, the Floquet periodic boundary condition (FPBC) is only valid for the acoustic elements FLUID30, FLUID220, and FLUID221.

In a mode-superposition harmonic or transient analysis, you must apply the load in the modal portion of the analysis. Mechanical APDL calculates a load vector and writes it to the MODE file, which you can apply via the LVSCALE command.

Graphical picking is available only via the listed menu paths.

Body load labels VELO, MASS, SPRE, FPBC, VMEN, UFOR, SFOR, and HFLW cannot be accessed from a menu.

This command is also valid in PREP7.

Menu Paths

Main Menu>Preprocessor>Loads>Define Loads>Apply>Electric>Boundary>Temperature>On Nodes

Main Menu>Preprocessor>Loads>Define Loads>Apply>Electric>Excitation>AppCharDens>On Nodes

Main Menu>Preprocessor>Loads>Define Loads>Apply>Electric>Excitation>AppElecField>On Nodes

Main Menu>Preprocessor>Loads>Define Loads>Apply>Fluid/ANSYS>Heat Generat>On Nodes

Main Menu>Preprocessor>Loads>Define Loads>Apply>Magnetic>Boundary>Temperature>On Nodes

Main Menu>Preprocessor>Loads>Define Loads>Apply>Magnetic>Excitation>AppCurrDens>On Nodes

Main Menu>Preprocessor>Loads>Define Loads>Apply>Magnetic>Excitation>AppMagField>On Nodes

Main Menu>Preprocessor>Loads>Define Loads>Apply>Magnetic>Other>AppVirtDisp>On Nodes

Main Menu>Preprocessor>Loads>Define Loads>Apply>Structural>Fluence>On Nodes

Main Menu>Preprocessor>Loads>Define Loads>Apply>Thermal>Heat Generat>On Nodes

Main Menu>Solution>Define Loads>Apply>Electric>Boundary>Temperature>On Nodes

Main Menu>Solution>Define Loads>Apply>Electric>Excitation>AppCharDens>On Nodes

Main Menu>Solution>Define Loads>Apply>Electric>Excitation>AppElecField>On Nodes

Main Menu>Solution>Define Loads>Apply>Fluid/ANSYS>Heat Generat>On Nodes

Main Menu>Solution>Define Loads>Apply>Magnetic>Boundary>Temperature>On Nodes

Main Menu>Solution>Define Loads>Apply>Magnetic>Excitation>AppCurrDens>On Nodes

Main Menu>Solution>Define Loads>Apply>Magnetic>Excitation>AppMagField>On Nodes

Main Menu>Solution>Define Loads>Apply>Magnetic>Other>AppVirtDisp>On Nodes

Main Menu>Solution>Define Loads>Apply>Structural>Fluence>On Nodes

Main Menu>Solution>Define Loads>Apply>Thermal>Heat Generat>On Nodes