SFA, Area
, LKEY
, Lab
, VALUE
, VALUE2
Specifies surface loads on the selected areas.
Area
Area to which surface load applies. If ALL, apply
load to all selected areas [ASEL]. If Area
= P, graphical picking is enabled and all remaining
command fields are ignored (valid only in the GUI). A component may
be substituted for Area
.
LKEY
Load key associated with surface load (defaults to
1). Load keys (1,2,3, etc.) are listed under "Surface Loads" in the
input data table for each element type in the Element Reference. LKEY
is ignored if the area is the face of a volume
region meshed with volume elements.
Lab
Valid surface load label. Load labels are listed under "Surface Loads" in the input table for each area type in the Element Reference.
Discipline | Body Load Label | Label Description |
---|---|---|
Structural | PRES | pressure |
Thermal | CONV[1] | convection |
HFLUX[1] | heat flux | |
RAD | radiation | |
RDSF | surface-to-surface radiation | |
Acoustic fluid | FSI[2] | fluid-structure interaction flag |
IMPD | impedance boundary flag | |
SHLD | surface normal velocity or acceleration | |
MXWF | Maxwell surface flag or equivalent source surface | |
FREE | free surface flag | |
INF | exterior Robin radiation boundary flag | |
PORT | Port number | |
ATTN | Attenuation coefficient | |
BLI | Viscous-thermal boundary layer surface flag | |
Magnetic | MXWF | Maxwell force flag |
Electric | CHRGS | surface charge density |
MXWF | Maxwell force flag | |
Infinite element | INF | Exterior surface flag for INFIN110 and INFIN111 |
Field-surface interface | FSIN | field-surface interface number |
VALUE
Surface load value or table name reference for specifying tabular boundary conditions.
If Lab
= CONV,
VALUE
is typically the film coefficient and
VALUE2
(below) is typically the bulk temperature. If
Lab
= CONV and VALUE
= -N
, the film coefficient may be a function of temperature and is
determined from the HF property table for material N
[MP]. (See the SCOPT command for a way to override this
option and use -N
as the film coefficient.) The
temperature used to evaluate the film coefficient is usually the average between the bulk and
wall temperatures, but may be user-defined for some elements.
If Lab
= RAD, VALUE
is the surface emissivity.
If Lab
= PORT, VALUE
is a port number representing a waveguide exterior port. The port
number must be an integer between 1 and 50. For acoustic 2×2
transfer admittance matrix, the port number can be any positive integer.
The smaller port number corresponds to the port 1 of the 2×2
transfer admittance matrix and the greater port number corresponds
to the port 2. If one port of the transfer admittance matrix is connecting
to the acoustic-structural interaction interface, the port number
corresponds to the port 2 of the transfer admittance matrix. A pair
of ports of the 2×2 transfer admittance matrix must be defined
in the same element.
If Lab
= SHLD, VALUE
is the surface normal velocity in harmonic analysis and the surface
normal acceleration in transient analysis for acoustics.
If Lab
= IMPD, VALUE
is resistance in (N)(s)/m3 if VALUE
> 0 and is conductance in mho if VALUE
< 0 for acoustics. In acoustic transient analyses, VALUE2
is not used.
If Lab
= RDSF, VALUE
is the emissivity value; the following conditions apply: If VALUE
is between 0 and 1, apply a single value to the
surface. If VALUE
= -N
, the emissivity may be a function of the temperature,
and is determined from the EMISS property table for material N
(MP). The material N
does not need to correlate with the underlying
solid thermal elements.
If Lab
= FSIN in a Multi-field solver
(single or multiple code coupling) analysis, VALUE
is the surface interface number and LKEY
is ignored. If Lab
= FSIN in a unidirectional
ANSYS to CFX analysis, VALUE
is not used
unless the ANSYS analysis is performed using the Multi-field solver.
If Lab
= ATTN, VALUE
is the attenuation coefficient of the surface.
VALUE2
Second surface load value (if any).
If Lab
= CONV, VALUE2
is typically the bulk temperature for thermal analyses. For acoustic
analyses, VALUE2 is not used. .
If Lab
= RADVALUE2
is ambient temperature.
If Lab
= SHLD, VALUE2
is the phase angle of the normal surface velocity (defaults to zero)
for harmonic response analyses while VALUE2
is not used for transient analyses in acoustics.
If Lab
= IMPD, VALUE2
is reactance in (N)(s)/m3 if VALUE
> 0 and is the product of susceptance and
angular frequency if VALUE
< 0 for acoustics.
If Lab
= RDSF, VALUE2
is the enclosure number. Radiation will occur
between surfaces flagged with the same enclosure numbers. If the enclosure
is open, radiation will also occur to ambient. If VALUE2
is negative, radiation direction is reversed and will occur inside
the element for the flagged radiation surfaces.
If Lab
= FSIN in a unidirectional
ANSYS to CFX analysis, VALUE2
is the surface
interface number (not available from within the GUI).
Surface loads may be transferred from areas to elements with the SFTRAN or SBCTRAN commands. See the SFGRAD command for an alternate tapered load capability.
Tabular boundary conditions (VALUE
= %tabname
% and/or VALUE2
= %tabname
%) are available for the following surface load labels (Lab
) only: PRES (real and/or imaginary components),
CONV (film coefficient and/or bulk temperature) or HFLUX, and RAD
(surface emissivity and ambient temperature). Use the *DIM command to define a table.
This command is also valid in PREP7.