SURF152 ## SURF152 Element Description

## SURF152 Input Data

### SURF152 Input Summary

## SURF152 Output Data

## SURF152 Assumptions and Restrictions

## SURF152 Product Restrictions

**3-D Thermal
Surface Effect**

Compatible Products: – | Pro | Premium | Enterprise | Ent PP | Ent Solver | –

SURF152 may be used for various load
and surface effect applications. It may be overlaid onto an area
face of any 3-D thermal element. The element is applicable to 3-D
thermal analyses. Various loads and surface effects may exist simultaneously.
See SURF152 in the *Mechanical APDL Theory Reference* for more details about this element.

The geometry, node locations, and the coordinate system for this element are shown in Figure 152.1: SURF152 Geometry. The element is defined by four to ten nodes and by the material properties. The nodes for this element must share the nodes of the underlying solid element. An extra node (away from the base element) may be used for convection or radiation effects. Two extra nodes (away from the base element) may be used to more accurately capture convection effects. A triangular element may be formed by defining duplicate K and L node numbers as described in Degenerated Shape Elements. The element x-axis is parallel to the I-J side of the element.

The mass, volume, and heat-generation calculations use the element thicknesses at node I, J, K, and L (real constants TKI, TKJ, TKK, and TKL, respectively). Thickness TKI defaults to 0.0, and thicknesses TKJ, TKK, and TKL default to TKI. The mass calculation uses the density (material property DENS).

See Nodal Loading for a description of element loads. Convections or heat fluxes may be input as surface loads on the element.

The convection surface conductivity matrix calculation uses
the film coefficient (input on the **SFE** command
with *KVAL* = 0 and *CONV* as the label). If the extra node is
used, its temperature becomes the bulk temperature. If the extra
node is not used, the *CONV* value
input with *KVAL* = 2 becomes the
bulk temperature. The convection surface heat flow vector calculation
uses the bulk temperature. On a given face, either a heat flux or
a convection may be specified, but not both simultaneously.

For the extra node option (KEYOPT(5) = 1), film effectiveness
and free stream temperatures may also be input for convection surface
loads (input on the **SFE** command with the *CONV* label and *KVAL* = 3 and 4, respectively). If film effectiveness is input, bulk temperature
is ignored.

Setting KEYOPT(7) = 1 multiplies the evaluated film coefficient
by the empirical term ITS - TBI^{n}, where
TS is the element surface temperature, TB is the fluid bulk temperature,
and n is an empirical coefficient (real constant ENN).

Convections and heat fluxes are multiplied by an area to obtain the heat flows. KEYOPT(12) determines whether the current area or the original area is selected for the calculation.

If KEYOPT(5) = 1 and flow information is available from FLUID116 with KEYOPT(2) = 1, the bulk temperature may
be adjusted to the adiabatic wall temperature using KEYOPT(6) = 1,
real constants OMEG (rotational speed) and NRF (recovery factor),
and the logic described in the *Mechanical APDL Theory Reference*. For this adjustment, the
axis of rotation may be defined as the global Cartesian X, Y or Z
coordinate axis (KEYOPT(3)). When using the OMEG real constant, you
can specify either numerical values or table inputs. If specifying
table inputs, enclose the table name in % signs (for example, %* tabname*%). Rotational speed (OMEG) can vary
with time and location. Use the

A film coefficient specified by the **SFE** command
may be modified by activating the user subroutine USERCV with the **USRCAL** command. USERCV may be used to modify the film
coefficient of a surface element with or without an extra node. It
may be used if the film coefficient is a function of temperature and/or
location.

If the surface element has an extra node (KEYOPT(5) = 1), the bulk temperature and/or the film
coefficient may be redefined in a general way by user programmable routine USRSURF116. USRSURF116
may be used if the bulk temperature and/or the film coefficient is a function of fluid
properties, velocity and/or wall temperature. If a bulk temperature is determined by USRSURF116,
it overrides any value specified by **SFE** or according to KEYOPT(6). Also, if a
film coefficient is determined by USRSURF116, it overrides any values specified by
**SFE** or USRCAL, USERCV. USRSURF116 calculation are activated by modifying the
USRSURF116 subroutine and creating a customized version of ANSYS; there will be no change in
functionality without modifying USRSURF116. For more information, see User-Programmable Features (UPFs) in the Mechanical APDL Advanced Analysis Guide.

Heat generation rates are input on a per unit volume basis and
may be input as an element body load at the nodes, using the **BFE** command. Element body loads are not applied to other
elements connected at the same nodes. The node I heat generation
HG(I) defaults to zero. If all other heat generations are unspecified,
they default to HG(I). If all corner node heat generations are specified,
each midside node heat generation defaults to the average heat generation
of its adjacent corner nodes. For any other input heat generation
pattern, unspecified heat generations default to zero. The heat generation
load vector calculation uses the heat generation rate values.

As an alternative to using the **BFE** command,
you can specify heat generation rates directly at the nodes using
the **BF** command. For more information on body loads,
see Body Loads in the *Basic Analysis Guide*.

SURF152 allows for radiation between
the surface and the extra node. The emissivity of the surface (input
as material property EMIS for the material number of the element)
is used for the radiation surface conductivity matrix. The form factor
FORMF and the Stefan-Boltzmann constant SBCONST are also used for
the radiation surface conductivity matrix. The form factor can be
either input as a real constant (defaults to 1) using KEYOPT(9) =
1 or it can be calculated automatically as a cosine effect using KEYOPT(9)
= 2 or 3. For information on how the cosine effect depends on basic
element orientation and the extra node location, see the *Mechanical APDL Theory Reference*.
There is no distance effect included in the cosine effect. The Stefan-Boltzmann
constant defaults to 0.119x10^{-10} (Btu/hr*in^{2}* °R^{4})).

When KEYOPT(4) = 0, an edge with a removed midside node implies
that the temperature varies linearly, rather than parabolically, along
that edge. See Quadratic Elements (Midside Nodes) in the *Modeling and Meshing Guide* for more
information about the use of midside nodes.

A summary of the element input is given in "SURF152 Input Summary". A general description of element input is given in Element Input.

**Nodes**I, J, K, L if KEYOPT (4) = 1 and KEYOPT (5) = 0 I, J, K, L, M if KEYOPT (4) = 1 and KEYOPT (5) = 1 I, J, K, L, M, N if KEYOPT (4) = 1 and KEYOPT (5) = 2 I, J, K, L, M, N, O, P if KEYOPT (4) = 0 and KEYOPT (5) = 0 I, J, K, L, M, N, O, P, Q if KEYOPT (4) = 0 and KEYOPT (5) = 1 I, J, K, L, M, N, O, P, Q, R if KEYOPT (4) = 0 and KEYOPT (5) = 2 **Degrees of Freedom**KEYOPT(11) Setting DOF for all nodes except extra node(s) DOF for extra node(s) (KEYOPT(5) = 1 or 2) 0 TEMP TEMP 1 TTOP TEMP 2 TBOT TEMP **Real Constants**FORMF, SBCONST, (Blank), OMEG, NRF, VABS, TKI, TKJ, TKK, TKL, (Blank), (Blank), ENN, GC, JC See Table 152.1: SURF152 Real Constants for a description of the real constants **Material Properties****MP**command: DENS (density), EMIS (emissivity) if KEYOPT(9) > 0)**Surface Loads****Convections --**face 1 (I-J-K-L) if KEYOPT(8) > 1

**Heat Fluxes --**face 1 (I-J-K-L) if KEYOPT(8) = 1

**Body Loads****Heat Generation --**HG(I), HG(J), HG(K), HG(L), and, if KEYOPT(4) = 0, HG(M), HG(N), HG(O), HG(P)

**Special Features****KEYOPT(1)**Adiabatic wall temperature option:

**0, 1, 2 --**See Adiabatic Wall Temperature as Bulk Temperature for information on these options.

**KEYOPT(2)**Recovery factor (F

_{R}) option:**0, 1, or 2 --**See Adiabatic Wall Temperature as Bulk Temperature for information on these options.

**KEYOPT(3)**Axis of symmetry:

**0 --**OMEG used about global Cartesian X-axis

**1 --**OMEG used about global Cartesian Y-axis

**2 --**OMEG used about global Cartesian Z-axis

**KEYOPT(4)**Midside nodes:

**0 --**Has midside nodes

**1 --**No midside nodes

**KEYOPT(5)**Extra nodes:

**0 --**No extra nodes. Use this option if the bulk temperature is known.

**1 --**One extra node (optional if KEYOPT (8) > 1; required if KEYOPT (9) > 0). Valid for convection and radiation calculations. Use this option if the bulk temperature is unknown. The extra node gets the bulk temperature from a FLUID116 element.

**2 --**Two extra nodes (optional if KEYOPT (8) > 1). Only valid for convection calculations. Use this option if the bulk temperature is unknown. The extra nodes get bulk temperatures from the two nodes of a FLUID116 element. This is generally more accurate than the one extra node option.

**KEYOPT(6) (used only if KEYOPT(5) = 1 and KEYOPT(8) > 1)**Use of bulk temperature:

**0 --**Extra node temperature used as bulk temperature

**1 --**Adiabatic wall temperature used as bulk temperature

**KEYOPT(7)**Empirical term:

**0 --**Do not multiply film coefficient by empirical term.

**1 --**Multiply film coefficient by empirical term |TS-TB|

^{n}.

**KEYOPT(8)**Heat flux and convection loads:

**0 --**Ignore heat flux and convection surface loads (if any)

**1 --**Include heat flux, ignore convection

Use the following to include convection (ignore heat flux):

**2 --**Evaluate film coefficient h

_{f}(if any) at average film temperature, (TS +TB)/2**3 --**Evaluate h

_{f}at element surface temperature, TS**4 --**Evaluate h

_{f}at fluid bulk temperature, TB**5 --**Evaluate h

_{f}at differential temperature, | TS - TB |

**KEYOPT(9)**Radiation form factor calculation:

**0 --**Do not include radiation

**1 --**Use radiation with the form factor real constant

**2 --**Use radiation with cosine effect calculated as an absolute value (ignore real constant)

**3 --**Use radiation with cosine effect calculated as zero if negative (ignore real constant)

**KEYOPT(11)**Label used for all nodal degrees of freedom (except for the extra node):

**0 --**TEMP

**1 --**TTOP

**2 --**TBOT

The extra node, if requested with KEYOPT(5) = 1, is always TEMP.

**KEYOPT(12)**Area to use for the heat-flow calculation:

**0 --**Current area (default)

**1 --**Original area

**KEYOPT(13)**Film coefficient matrix key:

**0 --**Program determines whether to use diagonal or consistent film coefficient matrix (default).

**1 --**Use a diagonal film coefficient matrix.

**2 --**Use a consistent matrix for the film coefficient.

**Table 152.1: SURF152 Real Constants**

No. | Name | Description |
---|---|---|

1 | FORMF | Form factor |

2 | SBCONT | Stefan-Boltzmann constant |

3 | (Blank) | -- |

4 | OMEGA | Angular velocity (KEYOPT(6) = 1) |

5 | NRF | Recovery factor |

6 | VABS | Absolute value of fluid velocity (KEYOPT(1) = 0) |

7 | TKI | Thickness at node I |

8 | TKJ | Thickness at node J (defaults to TKI) |

9 | TKK | Thickness at node K (defaults to TKI) |

10 | TKL | Thickness at node L (defaults to TKI) |

11-12 | (Blank) | -- |

13 | ENN | Empirical coefficient |

14 | GC | Gravitational constant used for units consistency |

15 | JC | Joule constant used to convert work units to heat units |

The solution output associated with the element is in two forms:

Nodal degree of freedom results included in the overall nodal solution

Additional element output as shown in Table 152.2: SURF152 Element Output Definitions

Convection heat flux is positive out of the element; applied
heat flux is positive into the element. A general description of
solution output is given in Solution Output. See the *Basic Analysis Guide* for
ways to view results.

**The Element Output Definitions table uses
the following notation:**

A colon (:) in the
Name column indicates that the item can be accessed by
the Component Name method (**ETABLE**, **ESOL**). The O column indicates the availability of the items in the file **Jobname.OUT**. The R column indicates the availability of
the items in the results file.

In either the O or R columns,
“Y” indicates that the item is *always* available, a number refers to a table footnote
that describes when the item is *conditionally* available, and “-” indicates that the item is *not* available.

**Table 152.2: SURF152 Element Output Definitions**

Name | Definition | O | R |
---|---|---|---|

EL | Element Number | Y | Y |

SURFACE NODES | Nodes - I, J, K, L | Y | Y |

EXTRA NODE | Extra node (if present) | Y | Y |

MAT | Material number | Y | Y |

AREA | Surface area | Y | Y |

VOLU: | Volume | Y | Y |

XC, YC, ZC | Location where results are reported | Y | 7 |

VN(X, Y, Z) | Components of unit vector normal to center of element | - | Y |

DENSITY | Density | - | 1 |

MASS | Mass of element | - | 1 |

HGEN | Heat generations HG(I), HG(J), HG(K), HG(L), HG(M), HG(N), HG(O), HG(P) | 2 | - |

HEAT GEN. RATE | Heat generation rate over entire element (HGTOT) | 2 | 2 |

HFLUX | Input heat flux at nodes I, J, K, L | 3 | - |

HEAT FLOW RATE | Input heat flux heat flow rate over element surface area (HFCTOT) | 3 | 3 |

HFILM | Film coefficient at each face node | 4 | 4 |

TBULK | Bulk temperature at each face node or temperature of extra node | 4 | 4 |

TAVG | Average surface temperature | 4 | 4 |

TAW | Adiabatic wall temperature | 5 | 5 |

RELVEL | Relative velocity | 5 | 5 |

SPHTFL | Specific heat of the fluid | 5 | 5 |

RECFAC | Recovery factor | 5 | 5 |

CONV. HEAT RATE | Convection heat flow rate over element surface area (HFCTOT) | 4 | 4 |

CONV. HEAT RATE/AREA | Average convection heat flow rate per unit area | 4 | - |

EMISSUR | Average emissivity of surface (for element material number) | 6 | 6 |

EMISEXT | Emissivity of extra node | 6 | 6 |

TEMPSUR | Average temperature of surface | 6 | 6 |

TEMPEXT | Temperature of extra node | 6 | 6 |

FORM FACTOR | Average form factor of element | 6 | 6 |

RAD. HEAT RATE | Radiation heat flow rate over entire element (HRTOT) | 6 | 6 |

RAD. HEAT RATE/AREA | Average radiation heat flow rate per unit area | 6 | - |

Available only at centroid as a

***GET**item.

Table 152.3: SURF152 Item and Sequence Numbers lists output available through
the **ETABLE** command using the Sequence Number method.
See The General Postprocessor
(POST1) in the *Basic Analysis Guide* and The Item and Sequence Number Table in
this reference for more information. The following notation is used
in Table 152.3: SURF152 Item and Sequence Numbers:

**Name**output quantity as defined in Table 152.2: SURF152 Element Output Definitions

**Item**predetermined Item label for

**ETABLE**command**E**sequence number for single-valued or constant element data

**I,J,K,L**sequence number for data at nodes I, J, K, L

**Table 152.3: SURF152 Item and Sequence Numbers**

Output Quantity Name | ETABLE and ESOL Command Input | |
---|---|---|

Item | E | |

HGTOT | SMISC | 1 |

HFCTOT | SMISC | 2 |

HRTOT | SMISC | 3 |

AREA | NMISC | 1 |

VNX | NMISC | 2 |

VNY | NMISC | 3 |

VNZ | NMISC | 4 |

HFILM | NMISC | 5 |

TAVG | NMISC | 6 |

TBULK | NMISC | 7 |

TAW | NMISC | 8 |

RELVEL | NMISC | 9 |

SPHTFL | NMISC | 10 |

RECFAC | NMISC | 11 |

EMISSUR | NMISC | 12 |

EMISEXT | NMISC | 13 |

TEMPSUR | NMISC | 14 |

TEMPEXT | NMISC | 15 |

FORM FACTOR | NMISC | 16 |

DENS | NMISC | 17 |

MASS | NMISC | 18 |

The element must not have a zero area.

If KEYOPT(9) > 0 (radiation is used):

element is nonlinear and requires an iterative solution

extra node must be present.

if KEYOPT(4) = 0, midside nodes may not be dropped.

If real constants TKI, TKJ, TKK, TKL (in-plane thicknesses), and TKPS (out-of-plane thickness) are defined for the element, the element volume is greater than zero. If

**BF**,**BFE**, or**BFUNIF**commands are issued under this circumstance, heat generation loads are activated. However, the damping matrix is not activated even though the element volume is greater than zero.

When used in the product(s) listed below, the stated product-specific restrictions apply to this element in addition to the general assumptions and restrictions given in the previous section.

**ANSYS Mechanical Pro **

Birth and death is not available.

**ANSYS Mechanical Premium **

Birth and death is not available.