This form appears when the Input Properties button is selected on the Element Properties form and the following options have been applied.

This is a point element used to define the type of node.

Patran Thermal uses bar elements for the following purposes:

In 2-D Cartesian (X-Y) space, conductive bars actually represent 2-D shell elements Figure 4‑1. The shell elements are by definition (and in accordance with standard finite element practice) assumed to be of unit depth in the Z direction. Using the 2-D bar elements as “shells” allows them to be used in conjunction with surface area boundary conditions such as convection, radiation, and heat fluxes. 2-D Cartesian elements must be built in the Patran X-Y plane.

Conduction bars will generate conductive resistors between the two-end nodes of the bar and will also generate capacitors for each node. These bars must be element property data consisting of the following:

The two thickness values allow for a linear variation of thickness along the bar axis. The average thickness is used (along with the assumption of unit depth along the Z-axis) to compute an effective cross-sectional area for the thermal resistors, and the distance between the bar nodes is used to compute an effective length. Capacitance volumes are computed based on the linear variation of thickness assumption coupled with the half-length of the bar.

Conduction bar elements, without capacitance for 2-D Cartesian models, are similar, except that no capacitors are generated.

Conductive bar elements will be interpreted as 2-D Cartesian when the Model Dimensionality has been specified as 2-D Plane Geometry under Analysis/ Translation Parameters.

This bar element is used to define conduction heat transfer.

Advection is the transport of heat energy by a mass flow stream. Advection bars generate advective resistors and no capacitors. These data items consist of the following:

If no MPID number is given for the variable mass flow rate, the constant MDOTC will be taken as the constant mass flow rate for the advective bar and for the resulting QTRAN advective resistors. If the optional MPID number for a variable mass flow rate is also given, then the MDOTC value is used as a scale factor and the effective mass flow rate is computed from the product of the MPID's value and MDOTC.

Mass flow is considered positive in the direction of element node 1 to element node 2, and negative from element node 2 to element node 1.

This bar element is used to define the flow of a fluid when the mass flow rate is known.

Flow networks transport head energy by a mass flow stream. The mass flow rates are computed by Patran Thermal in flow network resistors, unlike advective resistors where mass flow rates are input by the user. Flow network bars generate “one way” flow resistors and no capacitors. These elements must be assigned element properties and the data field varies with the option selected for the element (tube, pump, turbine, check valve, plenum, etc.). These options and the correspondent data fields are given below.

This is a Flow Network Bar used for the hydraulics analysis.

Input required for the various options available for Flow Network Pipe.

This element is used to define a turbine in a flow network.

 

This element is used to define a pump in a flow network.

Input required for the options available for Pump.

This element defines a check valve in the flow network. A flow reversal would close the valve.

This is a list of data input available for creating the flow network bar element, which were not shown on the previous page. Use the scroll bars to view these properties.

Option 10, CHECK VALVE, constant physical and variable material properties for fluid flow in a tube. One way flow. If the fluid flow is not from NODE1 to NODE2, the diameter becomes zero ( 0.0 ). Material properties defined with MPID's. Requires template definition.

This is a head loss element used to define the losses in a flow network (e.g., losses in orifices, valves, bend, tees, etc.).

Option 8, LOSS ELEMENT or CONTROL VALVE, variable parameters for fluid flow in a tube. Parameters input in the Element Property form will be used as scale factors applied to the material property evaluations obtained for the MPIDs defined. Requires template definition.

This is a plenum element used in a flow network to define a large reservoir.

Option 11, PLENUM, constant physical and material properties. Conditions across a plenum element are unaffected by flow. The head can be altered by gravity.

Option 12, PLENUM, variable material properties. Conditions across a plenum element are unaffected by flow. The head can be altered by gravity. Material properties defined with MPIDs. Requires template definition.

Radiation symmetry elements are used to communicate to the thermal radiation viewfactor code that a radiation symmetry condition exists. Such a condition implies that your Patran element surfaces which have radiation boundary conditions should either be reflected across a plane or else rotated about an axis (see Figure 4‑2, Figure 4‑3, Figure 4‑6, and Figure 4‑4). As shown in Figure 4‑2, Figure 4‑3, and Figure 4‑4, the Patran Thermal system uses bar elements to denote reflections in 2-D (X-Y and R-Z) as well as rotational symmetry in 2-D and 3-D X-Y geometry.

Radiation symmetry elements in R-Z models always denote reflection about a plane parallel to the R axis.

Radiation symmetry elements in 2-D X-Y space without Element Property data always denote reflection across a plane.

Radiation symmetry elements in 2-D X-Y or 3-D X-Y-Z space always denote rotational symmetry, with the model being rotated a number of times by an angular increment (see Figure 4‑4). The data for these rotational symmetry elements include (1) the number of rotations and (2) the angular increment for each successive rotation.

The nodes on these symmetry bars must have OD elements with Node Type of Information. Type I nodes are not passed through to the Solver during the translation process. This allows radiation symmetry elements to be built and their associated nodes do not participate in the thermal analysis calculations.

These rotational symmetry bar elements data consist of the number of incremental rotations followed by the angular increment for each rotation. Since this model is 2-D X-Y, the bar must be parallel to the Z-axis. In 3-D X-Y-Z, the bar may be arbitrarily oriented. Rotational symmetry bars are illegal for 2-D R-Z models.

This bar element is used to define radiation rotation symmetry.

If the model is an R-Z-axisymmetric model, the bar elements are also treated as 2-D shell elements with surface areas for convection, radiation, and heat flux boundary conditions (see Figure 4‑5). The bars (or shells) are assumed to be rotated 360° about the Z-axis. Any of Patran's X, Y, or Z-axis can be selected as the Z-axis (the axis of symmetry) by making the selection under Analysis/Translation Parameters.

As with the 2-D Cartesian bar elements, you must define element properties with a material and two thickness values (thickness at node 1 and thickness at node 2).

This bar element is used to define thin axisymmetric shells.

This property can use 1D bar element to simulate a 2D plate, such as a wall. The plate can be tapered along the 1D element direction, but unlimited length along another direction which is defined by "Definition of X,Y plane". You can think of the Great Wall in China, when you do not care about the temperature gradient along its thickness and length. You only want to know the temperature gradient from its top to the bottom (along the 1D bar direction). Patran Thermal may internally give a unit thickness for the length of the plate for conduction calculation, but that length does not affect the thermal result. Please read Axisymmetric Bar, 85 for additional information. The difference in these two bar elements is that: Thermal 2D bar is for a plate with an unlimited length, while the axisymmetric bar is for a round plate and the extension directions are different.

Patran Thermal supports 3-node linear triangular elements in either 2-D or 3-D Cartesian (X-Y or X-Y-Z) geometry or in 2-D axisymmetric (R-Z) geometry. 2-D Cartesian X-Y models must be built in the Patran X-Y plane. Whether the model dimensionality is 2-D X-Y, 2-D R-Z, or 3-D X-Y-Z is declared under Analysis/ Translation Parameters. Patran cannot tell the difference between any of these coordinate systems.

Allowed triangular elements include the following:

The 2-D X-Y triangles are assumed to be of unit thickness in the Z direction. The 2-D R-Z triangles are assumed to be rotated through 360 degrees. The 3-D X-Y-Z conductive triangles (3-D shell elements) may be oriented at any angle and must have thickness data at each node. 2-D triangular elements do not use any thickness data.

For 3-D conductive triangular shell elements, all three orientation angles may be supplied, as well as the three thickness values.

Patran Thermal supports 4-node quadrilateral elements in the following geometries:

2-D Cartesian X-Y models must be built in the Patran X-Y plane. 2-D axisymmetric R-Z models may be built in any plane defined by two Patran axes, e.g., X-Y, Y-Z, X-Z. The dimensionality of the model; i.e., 2-D X-Y, 2-D R-Z, or 3-D X-Y-Z is defined under Analysis/Translation Parameters.

The 2-D X-Y quadrilaterals are assumed to be of unit thickness, the 2-D R-Z quadrilaterals are assumed to be rotated through 360 degrees, and the 3-D X-Y-Z quadrilateral shell elements must be given thickness data.

Both 2-D Cartesian and 3-D shell elements support boundary conditions applied through their edges.

This form applies to quad and tri shell elements and require thickness definitions.

Rotations reference a cylindrical coordinate system.

Rotations reference the elemental coordinate system (Nastran definition).

This form applies to 2D elements. In Patran Thermal, they are treated as unit depth.

This form applies to axisymmetric quad and tri elements.

This form is typically used when modeling a mixed Axisymmetric and 3D model. It applies to axisymmetric quad and tri elements.

No input properties required.

The 3-D symmetry triangular element shown in Figure 4‑6 happens to lie in the X-Y Plane. This is not required for 3-D symmetry triangular elements. Radiating element surfaces will be reflected across the plane defined by the triangular element. Nodes on these symmetry triangular elements must have OD elements with Node Type “Information.” These nodes will not participate in the thermal analysis calculations.

Convective quadrilateral elements may be used to apply convective boundary conditions to 2-D X-Y or 2-D R-Z models (see Figure 4‑7). The advantage of using convective quadrilateral elements as opposed to the CONV LBC form occurs when a spatial variation of fluid temperature along a fluid-surface interface occurs, and it is necessary to model the fluid as a series of nodes paralleling the surface.

The shaded elements in Figure 4‑7 represent convective quadrilateral elements. These elements may be used to apply convective boundary conditions to surfaces where the fluid temperature is to be represented by a series of fluid nodes. The data for convective quadrilateral elements consist of the CONV template TID number, followed by as many GP values (geometric properties) needed to supply from Patran. The remaining GP values will be taken, as with the CONV LBC form, from the CONV template.

Typically, the fluid nodes are chained together with advective bar elements to model the energy being carried along on the mass flow stream. The fluid nodes determine which nodes should have convective resistors generated between them to apply the correct convective boundary conditions for the model.

Convective quadrilaterals must have at least one fluid node associated with each element. Note that if a convective quadrilateral element has fewer than two surface thermal nodes, there is no surface area associated with the element and hence no convective resistors will be generated for the element. This typically occurs at convex corners.

This is a convective quad element used to define convective heat transfer between solid and fluid. No cross resistors are generated for convective quad elements.

Patran Thermal supports 4-node tetrahedral elements for conduction in 3-D Cartesian coordinates. Patran Thermal also supports 6-node wedge elements for conduction in 3-D Cartesian coordinates.

Patran Thermal supports 8-node hexahedral elements for conduction in 3-D Cartesian coordinates. FE Hex elements generate conductive resistors and capacitors using a finite element formulation. Finite Diff Hex elements generate conductive resistors and capacitors using a finite element formulation on skewed or orthotropic elements and a finite difference formulation on rectangular isotropic elements. The advantage of this approach is that models typically run somewhat faster than the pure finite element models with virtually no loss of accuracy.

This form applies to three-dimensional, isoparametric solid elements.

This form applies to finite difference orthogonal hex elements.

This form is typically used for mixed axisymmetric and 3D models. The axisymmetric portion is treated as a 360-degree rotation and the 3D elements are applied a multiplying factor to scale the capacitance and surface area by the number of times the 3D component repeats.

Convective hexahedral elements can be used to generate convective resistors between Convective Fluid nodes and Thermal Surface nodes (see Figure 4‑8). Any one face of a Convective hexahedral element may be defined by type Fluid nodes, but the remaining 4 nodes must be type Thermal.

These elements can also be used to specify contact coefficients (contact resistance) between surfaces.

Patran Thermal supports convective wedge elements. These elements can be used to generate convective resistors between Fluid nodes and Thermal solid nodes. Valid convective wedge elements are shown in Figure 4‑9.

As can be seen in Figure 4‑9, any one triangular face may have all type F nodes, or the degenerate edge (nodes 1 and 4) may be type F nodes. Any other arrangement is illegal. These elements can also be used to define contact resistances. These elements must be given Element Properties consisting of a CONV Template ID pointer and appropriate geometric parameters for the chosen configuration.

These are convective hex/wedge elements used to define convective heat transfer between solid and fluid. No cross resistors are generated for convective hex/wedge elements.