Boudary Grip Points

• Icon:

• Command: RcGripsBoundary

• Ribbon: Thermal > Grips > Boundary

When the above command is issued, the user must select the object(s) for which to change the displayed grip type, unless a primitive is pre-selected. Boundary grips points allow moving the nodes and the nodal boundaries within an object.

Grips labeled Adjust Node Boundary are on each node boundary line and adjust the location of the node boundaries along the principal directions (normal to the node boundary line). When the node boundaries are moved, the nodes will always adjust to be half way between two boundaries.

Grips labeled Adjust Node Locations are on each row of nodes in a principal direction and adjust the location of the nodes in the principal directions. When a row of nodes is moved, the node boundaries on either side of the row of nodes are adjusted to be equidistant from the row of nodes.

Note: Since only the adjacent node boundaries are moved with the Adjust Node Locations grips, the rows of nodes can moved a limited distance to prevent collapsing the adjacent row of nodes.

2.10.4 Comment Field

Most forms for editing network objects (surfaces, solids, elements, conductors, pipes, nodes, lumps, etc.) will have a field to enter a comment (the field may also be titled Name). This comment allows the user to enter information about the object. By double-clicking in the field, the user opens a text edit form that allows multi-line comments. The first line of the comment will be used in the tool-tip when the cursor is paused over an object and also in the object name in the Model Browser listing (Section 2.4).

2.10.5 Register Append String

Objects such as heaters and thermoelectric coolers (TEC) generate special variables to store information during the solution. These variables in SINDA/FLUINT are called regis- ters. Thermal Desktop generates a set of these registers in SINDA/FLUINT for each heater or TEC. To differentiate one heater (or TEC) from another, the registers start with common characters followed by a unique character string. On the edit forms, the Register Append String field contains the unique character string. The default string is automatically generated but can be replaced with a meaningful character string up to 30 characters long.

As an example, the total energy used by a heater is calculated during the solution and stored in a register starting with “TP”. If the user types “Heater_1” in the Register Append String field, the register in SINDA/FLUINT will be “TPHEATER_1”. Allowable characters are letters, numbers and underscores (_).

2.10.6 Register Prefix

Heat exchangers allow definition of a Register Prefix. A register prefix is added to the beginning of a automatically generated register name. The generated registers contain values specific to heat exchangers and are updated during the SINDA/FLUINT solution. The Reg- ister Prefix distinguishes the registers of one heat exchanger from another.

2.10.7 Expression Editor

An Expression Editor is available for input fields. Double clicking on an input field will invoke the Expression Editor shown in Figure 2-21. The expressions defined for input fields will have units associated with them. For newly defined input field expressions,

the units will be the appropriate defaults for the type of input field. For example, the input field for a heat load will have units defined for energy and time using the currently set user preferences. These units may be changed if desired.

The units defined for an input field do not change when the user preferences for units are modified. For example, suppose that an expression for the length of a rectangle is defined as 1.5 meters. If the user preferences for length units are changed to inches, the input field will show the value of 1.5 meters in inches (59.055). However, when the field is double clicked, the original expression and units will be displayed; they are not changed by the current user preferences.

When "OK" is selected on the input field Expression Editor, the expression is evaluated and the numeric result appears in the input field. The field is set to bold type so that the user can tell that the value was derived from an expression, rather than input directly. The ex- pression may be edited at any time by double clicking on the input field. If the user attempts to enter a numerical value in the input field, a warning dialog box will appear indicating that an expression is associated with the input. The user may then edit the expression, or delete it and continue with the direct numerical input.

The expression editor can also be used to provide a comment for the value in the input field. If a comment is placed in the expression editor’s comment field, the input field will be highlighted in blue as shown in Figure 2-22. An expression is not required to use the comment field: if a comment is added to the Expression Editor but the expression is left empty, the input field will be highlighted in blue while the input field value remains in non- bold type.

If the expression in the expression editor has a numerical error (e.g. - divide by zero), then a warning dialog box appears and the input field is highlighted in red. In case of an error in the expression, the expression will be equated to 1 until the error in the expression is resolved.

A Thermal Desktop model is parameterized by using variables (or expressions contain- ing variables) in the input fields of dialog boxes that ordinarily accept numerical input. This example shows the initial temperature of a node being defined using a variable. A symbolic expression may be entered, which when evaluated, will be the value of the input field. Existing Symbols may be added to the expression by right-clicking in the expression field and selecting the Symbol by navigating the menu of Symbol groups and Symbols. The

Symbol Manager (Section 11.1.1) is also accessible from the Expression Editor so that variables may be added on the fly, or so that the values of other variables may be examined during the definition of an input field expression. For more information on model parame- terization see Section 11 "Parameterization".

Note: Symbols can be added but not edited when accessing the Symbol Manager from the Expression Editor.

The Output Above Expression To SINDA checkbox is used to write the expression in SINDA in the context of the input field. In addition, all symbols used in the expression will be written to SINDA as registers. If the checkbox is checked, the expression will be evaluated and updated throughout the solution. If this option is greyed out, then the input field is required for Thermal Desktop or RadCAD calculations and is therefore not viable for up- dating during the solution. If Dynamic SINDA (Section 16.1) is used, then objects in Dy- namic submodels cannot have this option checked. Either the expression cannot be output to SINDA, it the object must be placed in a static submodel (Section 15.2.5)

Checking the Disable Warnings for this Expression checkbox will disable pop-up warnings if errors are found in the expression (divide by zero, undefined symbols, etc.). The field will still be highlighted as red, however.