Definitions

Assigned Temperature Part

A part that has a constant (known) temperature. The temperature can be a fixed value or can be described by a time dependent curve.

 

Back Side

The side of an element that does not have the surface normal directed out of it.

 

Bounding Box

WinTherm uses a box to simulate the environment of the model. This box bounds the geometry with an offset that is specified by the user. The walls of the box are assumed to be constant temperature with an emissivity of 1.0. The user can specify individual temperatures for each box face.

 

Boundary Conditions

Boundary conditions are known conditions that can be applied to a part. Assigned Temperature parts allow the specification of a temperature boundary condition. Calculated Temperature parts allow the specification of an imposed heat source, a convection coefficient, and a fluid temperature.

 

Conduction Types (also connectivity)

Face: Union of two parts or elements that share a common polygon (defined by common edges sharing the same vertices) that allows heat to be conducted across the common face.
Lateral: Union of two adjoining elements that allows heat to be conducted across the elements' common edge.

 

Calculated Part

A part that has an unknown temperature. Temperatures for elements of these parts will be calculated by WinTherm.

 

Convection Coefficient

A type of boundary condition that can be applied to the front or back side of calculated parts. Convection coefficients are normally applied in conjunction with a fluid temperature.

Curve

A set of data points that defines a time dependent property or boundary condition. Curves can be created with the Curve Editor. Curves can also specify other (e.g. temperature) dependent properties.

 

DXF File

An ASCII file format specified by AutoCAD for storing geometry information.  WinTherm can import geometry from a DXF file.

 

Element

A planar surface with 3 or more vertices. Element data is imported from the supported geometry files, or it can be created within WinTherm. Elements = facets = polygons = triangles or quadrilaterals = face. WinTherm expects convex elements.

 

Fluid Temperature

A type of boundary condition that can be applied to either side of calculated parts. The fluid temperature is normally applied in conjunction with a convection coefficient.

 

Front Side

The surface normal of an element is directed out of the front side.

 

Material Properties

A general name for type of material, material thickness, and surface condition.

 

Material Type

A material identification number that references the material being used. Specifying the Material Type is a specification of the material density, conductivity, and specific heat. The properties of a material can be examined by clicking the Material tab in the editor.

 

Part

A collection or grouping of elements having the same material properties and boundary conditions.

 

Part Name

An alphanumeric tag that can be associated with a part.

 

Part Number

The identification number for each part.

 

Part Type

Specifies the thermal type of the part. Assigned temperature,  calculated temperature, radiation on one side or both sides, internal layers, etc. The possible part types are Assigned Temperature and Calculated Temperature.

 

Patran Neutral File

An ASCII file format specified by MSC/PATRAN for storing geometry information. WinTherm can import geometry from a Patran Neutral file.

 

Plus Junction

An intersection of four elements in which there is a union at a common edge. Heat is conducted through an area based on length of the common edge and a user-specified thickness for the element.

 

Properties

Attributes of parts: thickness, material, surface, temperature assignments, heat loads, convection coefficient, etc.

 

Radiation Exchange Factor

A thermal exchange factor that includes the effects of multiple bounces. These factors are computed using View Factors and emissivities in WinTherm. Currently the thermal solver is using the Radiosity Method integrated into the thermal solution rather than the Gebhart Method which is used in previous TAI programs.

 

Radiation Patch

A collection of elements that are assumed to have similar view factors to other elements. WinTherm currently assigns a single radiation patch to each element.

 

Shell Geometry

A collection of elements and vertices that describe the surface of an object. This type of geometry has no thickness. MuSES/WT uses shell geometry to build thermal models. Also known as surface geometry as opposed to Solid Geometry.

 

STL File

A Stereolithography ASCII or Binary file format specified by many  CAD programs.  WinTherm can import geometry from an STL file.

 

Surface Condition

A surface type identification number that references the surface being used. Specifying the Surface Condition is a specification of the surface emissivity and solar absorptivity (future).

 

Tee Junction

An intersection of three elements in which there is a union along a common edge. Heat is conducted through an area based on length of the common edge and a user-specified thickness for the element.

 

Thermal Data File

A binary file format used by WinTherm to save the thermal models. This file format uses the Hierarchical Data Format (HDF) libraries, which defines a platform independent format. Files that are written on one machine can be easily read on another machine that uses a different internal data representation.

 

Thermal Node

The smallest isothermal entity that temperature calculation (or energy balance) takes place.  WinTherm assigns a single element to a node. NOTE that the geometric concept of a node has a different meaning and is actually a vertex.

 

Thermal Region

Another name for Radiation Patch.

 

Thickness

The thickness of a part.

 

Three Layer Part

The two-sided computed part that is made up of three separate layers and four nodes.  The middle layer can be a solid, or it can be an air or vacuum gap.  If air is specified, natural convection will be computed.

 

Vertex

A three dimensional geometric location, used for defining the edges of an element. Also known as coordinates, points, or nodes.

 

View Factor

A geometry exchange factor. These factors are computed when a model is run, and are used in the calculation of Radiation Exchange Factors.

 

Wavefront Object File

An ASCII file format specified by Wavefront/Alias for storing geometry information. WinTherm can import geometry from a Wavefront Object file.