SOLID291

3D 10-Node Tetrahedral Thermal Solid

SOLID291 Element Description

SOLID291 is well suited to model irregular meshes (such as produced from various CAD/CAM systems). The element has one degree of freedom, temperature, at each node.

The element is applicable to a 3D, steady-state or transient thermal analysis. See SOLID291 in the Mechanical APDL Theory Reference for more details about this element. If the model containing this element is also to be analyzed structurally, the element should be replaced by the equivalent structural element (such as SOLID187). A 20-node thermal solid element, SOLID279, is also available.

Figure 291.1: SOLID291 Geometry

SOLID291 Input Data

The geometry, node locations, and the coordinate system for this element are shown in Figure 291.1: SOLID291 Geometry.

Orthotropic material directions correspond to the element coordinate directions. The element coordinate system orientation is as described in Coordinate Systems. Specific heat and density are ignored for steady-state solutions. Properties not input default as described in the Material Reference.

Element loads are described in Element Loading. Convection or heat flux (but not both) and radiation may be input as surface loads at the element faces as shown by the circled numbers on Figure 291.1: SOLID291 Geometry. Heat generation rates may be input as element body loads at the nodes. If the node I heat generation rate HG(I) is input, and all others are unspecified, they default to HG(I). If all corner node heat generation rates are specified, each midside node heat generation rate defaults to the average heat generation rate of its adjacent corner nodes.

A summary of the element input is given in "SOLID291 Input Summary". A general description of element input is given in Element Input.

SOLID291 Input Summary

Nodes

I, J, K, L, M, N, O, P, Q, R

Degrees of Freedom

TEMP

Real Constants

None

Material Properties

TB command: See Element Support for Material Models for this element.

MP command: KXX, KYY, KZZ, DENS, C, ENTH

Surface Loads

Convection or Heat Flux (but not both) and Radiation (using Lab = RDSF) --: face 1 (J-I-K), face 2 (I-J-L), face 3 (J-K-L), face 4 (K-I-L)

Body Loads

Heat Generations --: HG(I), HG(J), HG(K), HG(L), HG(M), HG(N), HG(O), HG(P), HG(Q), HG(R)

Special Features

Birth and death

KEYOPT(11)

Specific heat matrix and material properties integration:

0: The specific heat matrix is evaluated using 4 integration points, and material properties are evaluated based on the KEYOPT(16) setting (default).
1 --: The specific heat matrix is evaluated using 11 integration points, and material properties are evaluated at all integration points.
2 --: The specific heat matrix is evaluated using 11 integration points, and material properties are evaluated at the element centroid.

Note: If KEYOPT(11) > 0, KEYOPT(16) is ignored.

For details on the number of integration points, see SOLID291 - 3D 10-Node Tetrahedral Thermal Solid in the Theory Reference.

KEYOPT(13)

Film coefficient matrix:

0 --: Program determines whether to use a diagonal or consistent film coefficient matrix (default). For details on default behavior, see Assumptions and Restrictions.
1 --: Use a diagonal film coefficient matrix.
2 --: Use a consistent film coefficient matrix.

Note: If THOPT,QUASI has been issued, the only valid choice for KEYOP(13) is 0.

KEYOPT(15)

Specific heat matrix:

0 --: Program determines whether to use a diagonal or consistent specific heat matrix.
1 --: Use a diagonal specific heat matrix.
2 --: Use a consistent specific heat matrix (default).

KEYOPT(16)

Valid only for KEYOPT(11) = 0. Evaluation of material properties (except for density and specific heat, which are always evaluated at the integration points):

0 --: Evaluate material properties at centroid (default).
1 --: Evaluate material properties at each integration point.

Note: If THOPT,QUASI has been issued, KEYOPT(16) is ignored and material properties are evaluated at the centroid.

SOLID291 Output Data

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

Nodal temperatures included in the overall nodal solution
Additional element output as shown in Table 291.1: SOLID291 Element Output Definitions.

Convection heat flux is positive out of the element; applied heat flux is positive into the element. The element output directions are parallel to the element coordinate system. 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 letter or number refers to a table footnote that describes when the item is conditionally available, and “-” indicates that the item is not available.

Table 291.1: SOLID291 Element Output Definitions

Name	Definition	O	R
EL	Element Number	Y	Y
NODES	Nodes - I, J, K, L, M, N, O, P, Q, R	Y	Y
MAT	Material number	Y	Y
VOLU:	Volume	Y	Y
XC, YC, ZC	Location where results are reported	Y	2
HGEN	Heat generations HG(I), HG(J), HG(K), HG(L), HG(M), HG(N), HG(O), HG(P), HG(Q), HG(R)	Y	-
TG:X, Y, Z, SUM	Thermal gradient components and vector sum at centroid	Y	Y
TF:X, Y, Z, SUM	Thermal flux (heat flow rate/cross-sectional area) components and vector sum at centroid	Y	Y
FACE	Convection face label	1	-
NODES	Convection face corner nodes	1	-
AREA	Convection face area	1	1
HFILM	Film coefficient	1	-
TAVG	Average face temperature	1	1
TBULK	Fluid bulk temperature	1	-
HEAT RATE	Heat flow rate across face by convection	1	1
HEAT RATE/AREA	Heat flow rate per unit area across face by convection	1	-
HFAVG	Average film coefficient of the face	-	1
TBAVG	Average face bulk temperature	-	1
HFLXAVG	Heat flow rate per unit area across face caused by input heat flux	-	1
HFLUX	Heat flux at each node of face	1	-

Output if a surface load is input
Available only at centroid as a *GET item.

Table 291.2: SOLID291 Item and Sequence Numbers lists output available through the ETABLE command using the Sequence Number method. See Creating an Element Table 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 291.2: SOLID291 Item and Sequence Numbers:

Name: output quantity as defined in the Table 291.1: SOLID291 Element Output Definitions
Item: predetermined Item label for ETABLE command
FCn: sequence number for solution items for element Face n

Table 291.2: SOLID291 Item and Sequence Numbers

Output Quantity Name	ETABLE and ESOL Command Input
Output Quantity Name	Item	FC1	FC2	FC3	FC4
AREA	NMISC	1	7	13	19
HFAVG	NMISC	2	8	14	20
TAVG	NMISC	3	9	15	21
TBAVG	NMISC	4	10	16	22
HEAT RATE	NMISC	5	11	17	23
HFLXAVG	NMISC	6	12	18	24

SOLID291 Assumptions and Restrictions

The element must not have a zero volume.
Elements may be numbered either as shown in Figure 291.1: SOLID291 Geometry or may have node L below the IJK plane.
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.
Plotting temperature in /POST1 is based on corner nodes only. To include midside nodes in the plot, issue /EFACET,2 before PLNSOL,TEMP.
The full Newton-Raphson solution option (THOPT,FULL) must be used if thermal properties are defined via TB,THERM.
If enthalpy is defined, density and specific heat will be ignored.
The default for KEYOPT(13) is to use a consistent film coefficient matrix with midside nodes film coefficient values set to zero.

SOLID291 Product Restrictions

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.

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