Glossary

A path that specifies all the directories containing a file starting from the root of the file system (Linux), the root of a particular drive such as C: (Windows), or the root of the network (also Windows). A path is absolute when it begins with a drive letter or a slash.

A plug-in software module for Tecplot 360. The Chorus add-on allows certain Tecplot Chorus features to be integrated tightly with Tecplot 360.

Generally, to add more data to the end of a file. In Tecplot Chorus, refers to the ability to add new cases and/or variables to a project.

An image or data file associated with a specific case in a Tecplot Chorus project.

See job.

A variable in a Tecplot Chorus project calculated from other variables in the project using a formula you provide.

A simulation or experiment carried out for a given combination of input variables or parameters. In Tecplot Chorus, a case is represented by a record that stores the input variables, the output or result variables, informational fields, and links to auxiliary files. Compare with run.

An internal Tecplot Chorus variable that uniquely identifies each case record. Case ID is an integer that starts at 1 for the first imported case and increases by 1 for each additional case. The variable name "Case ID" is reserved for use by Tecplot Chorus.

An internal Tecplot Chorus variable that indicates whether cases are active or inactive, allowing inactive cases to be filtered from the view. It can be set by selecting cases in any Tecplot Chorus view and clicking the right mouse button. This variable is added to the project the first time it is used, so it might not exist in a given project. If it does not exist, all cases are active. The variable name "Case Status" is reserved for use by Tecplot Chorus.

See computational fluid dynamics.

A filter that allows values of a given variable to be selected for display by clicking a checkbox. Best suited for variables having a small number of discrete values.

A plug-in module that allows the integration of certain Tecplot Chorus features into Tecplot 360. These features can be found in the Chorus sidebar in Tecplot 360.

An approach to analyzing fluid flow problems (such as the location and magnitude of the vortices created by an airfoil as wind passes over it) using numerical methods and algorithms, rather than by examining a model in a wind tunnel.

Generally, a program that scans a file system, the Web, or some other external data source and imports information about the data it finds into a database. See file crawler for its use in Tecplot Chorus.

Short for "comma-separated-value file." A type of delimited text file in which a comma is used as the delimiter. Frequently used for data interchange.

See view.

From Tecplot Chorus, viewing the data for a given case or cases in Tecplot 360. The metaphor is that the aggregate view of all your cases in Tecplot Chorus is the surface of a vast ocean of data. To investigate cases of interest in more detail, you dive deeper, inspecting the full case data (not just the metadata) in Tecplot 360.

A plain-text file that typically contains data to be imported to a project, with a delimiter such as a tab or a comma between each field in a given line. When a comma is used, the file is often called a CSV file. When importing data into Tecplot Chorus from such a file, each line in the file represents a single case, and the individual values in that line are the variables associated with the case.

A character that separates the fields in a data record. For example, in a directory path like C:\Users\John, the backslash is used as a delimiter for the directories in the path. In a CSV file, the delimiter is a comma, and is used to separate the fields on each line of the file.

The output or result of a computation (and sometimes these terms are used instead). For example, an aerodynamic simulation of an airfoil design will have outputs such as lift and drag, which will be described in Tecplot Chorus as being dependent variables.

In Tecplot Chorus, the action of storing generated image or data files into a project. These files are generated by a background process but are not stored in the project until you specifically instruct Tecplot Chorus to deposit them.

An abstract space (possibly highly dimensional) consisting of all the possible values of the input variables in an experiment. A CFD experiment is often an attempt to search the design space for an optimal design for an aircraft or a component such as an airfoil.

In general, a visual representation of the differences between two files ("a diff"), or, as a verb, the action of producing such a representation ("diff these images"). Tecplot Chorus can produce diffs of multiple images associated with cases or, in a deep dive, you can have Tecplot 360 produce diffs of actual data files.

The name by which a variable in a given project is known and displayed in Tecplot Chorus. This may be different from the way the variable is identified in the original files. Variable names may be mapped to display names when the variable is added to a Tecplot Chorus project. For example, a variable may be called "M" in the original data, but "Mach Number" in Tecplot Chorus.

The Filter and Options panels in Tecplot Chorus may be dragged to the edges of the Tecplot Chorus window or to each other and will "stick" to these elements, and are then said to be "docked" to the window. When you move the edge of the window, for example to resize it, the panels move with it. These two panels can also be docked together in a single space; only one will be visible at a time in this case, with the visible panel chosen by a tab.

When a variable is used in some fashion in a plot (for example, as an axis, or to determine the size or color of a symbol on a scatter plot), it is said to be employed by the plot.

The collection of query values to be used for surrogate model input variables that are not being used in a plot. Only one value is used per variable.

A group of related CFD cases (or other calculations or real-world tests) intended to investigate an engineering issue or to optimize a design, e.g. of an airfoil. The required input variables, their ranges, and the specific values of each variable to be tested (i.e., the design space), along with the outputs to be generated, form the basis of an experiment. An experiment usually, but not always, corresponds to a Tecplot Chorus project.

Generally, to save data to a format that makes interchange easier. In Tecplot Chorus, you may export a project to a CSV file for sharing with others or for importing to a spreadsheet for further analysis or for publication.

A mathematical formula; in computer software, usually one entered using a special notation or syntax that is easier to type on a computer keyboard than traditional mathematical notation. In Tecplot Chorus, you can create calculated variables by entering an expression.

A Tecplot Chorus feature that scans the directories (folders) on a disk or network share to extract variable names and values for the cases in a project, based on the names of the directories in which the case’s data files are found.

Generally, to exclude unwanted data items from consideration or display based on some criteria, or (as a noun) a mechanism for doing this. In Tecplot Chorus, you may filter based on the values of any variable in the project using checkboxes or listboxes of discrete values, ranges, or single values.

Generally, any data that is not in a program’s native format. In Tecplot 360, native formats include .dat, .plt, .szplt, .lay, and .lpk files. Foreign data formats include CGNS, Fluent, PLOT3D, and other popular solver output file formats. Tecplot 360 can read these formats, but this is an import operation; it cannot write these formats.

A mathematical rule that associates given inputs to an output. In Tecplot Chorus, a function (also called an expression) may be used to calculate new variables from existing variables in a project. Also, the functions implied by a project’s metadata may be approximated using the surrogate model feature.

Describes a data set with many input variables, each of which describes a dimension of the design space. It is difficult for most people, even mathematicians or engineers, to visualize and reason about abstract spaces having more than three or four dimensions because human beings have such little everyday experience with higher-dimensional data. Many CFD projects have more than a dozen parameters or dimensions.

A plot showing the relative frequency of values in a variable’s range, often with values grouped into bins. For example, the range filter in Tecplot Chorus includes a histogram showing where the most frequently-appearing values can be found in a variable’s range.

Generally, to read data that is not in a program’s native format. Tecplot Chorus can import project metadata from a delimited text file, from a directory structure using its file crawler, or from the auxiliary data stored in solution data. Tecplot 360 can import grid and solution data in a variety of formats.

A variable that is being manipulated or changed to investigate the effects on a function to which it is an input. For example, in a CFD simulation of flow around an airfoil, Mach Number, alpha, and beta are common independent variables. Also called an input or parameter.

A synonym for independent variable, usually paired with output.

In Tecplot Chorus, a background process that creates images or Tecplot 360 layout packages, or extracts variables, from the data files associated with selected cases in a project. When such a process is in operation, the Manage Jobs button in Tecplot Chorus’s status line becomes available to allow you to delete jobs or deposit their results into the project.

A least-squares estimation method, originally from geology, that allows the value of a variable at an unobserved (i.e., unsimulated) location in design space to be approximated from the values of the variable at nearby locations using a function called a variogram. A more sophisticated technique than a response surface, Kriging guarantees that the generated shape will pass through all observed points. Tecplot Chorus can use Kriging to generate a surrogate model.

In Tecplot 360, a file that stores the appearance of the current plot, including which zones and variables are displayed, the visual style of each, the zoom and rotation, and so on, along with references to the files that contain the data sets. The actual data is not stored in the file.

In Tecplot 360, a layout file that also includes the data necessary to reproduce the plot as specified in the layout file. Data for zones or variables that are not visible is not included, and the data is stored in Tecplot’s binary format, so layout packages can be much smaller than the original data file. They are a good format for sharing with others, since they can be viewed with the free Tecplot Viewer.

In Tecplot Chorus, a guide to the colors or line patterns used in a plot.

In Tecplot Chorus, a two-dimensional plot that places cases on a grid based on the value of two variables, connecting adjacent cases with lines. The lines can be grouped based on the value of a third variable, in which case a separate line is drawn, in a different color, for each discrete value of this variable.

In Tecplot Chorus, a text variable that specifies the path of an auxiliary file associated with a case. The auxiliary files are not stored in the project, so their path (relative to the project root) serves to link the case record in the Tecplot Chorus project to the image or data file stored elsewhere.

A filter that allows values of a given variable to be selected for display by selecting them in a scrolling list. Best suited for variables having a large number of discrete values.

A macro (.mcr file) is a way of automating Tecplot 360. Virtually anything you can do in Tecplot 360 can be recorded in a macro and later played back with entirely different data. Tecplot Chorus can automatically run a macro when opening data files in Tecplot 360 or when generating images or layout packages, allowing you to customize the process as needed.

In an image or data comparison (diff), the image or data file to which other images or data files are compared. Differences from the master are shown for each file being compared with it.

A view of a Tecplot Chorus project that shows image thumbnails for cases that have them. Variables can be chosen to sort the cases into rows, columns, and optionally pages.

In general, means "data about data." In Tecplot Chorus, refers to the independent variables (inputs) used in each case, the derived dependent variables (outputs) calculated by the solver—such as lift, drag, and pressure—aggregated over the entire solution, links to related files, and, often, housekeeping information such as the name of the engineer who ran the simulation, the date it was run, a case serial number, and so on. Does not refer to the full solution data (i.e., the outputs for each cell in a grid). Tecplot Chorus is a tool for organizing cases and visualizing your design space based on metadata; Tecplot 360 is a tool for visualizing individual cases' solution data.

See surrogate model.

Means "Not a Number." The text "NaN" may be included in numeric data to indicate that a value is missing or invalid for a particular case. Tecplot Chorus refers to "NaN" as a null value.

See variable nature.

A missing or invalid value of a variable, which can be designated as NaN ("Not a Number") in a delimited text file. You can use filters to show or hide cases having null values.

A symbol representing an arithmetic operation: In Tecplot Chorus, + for addition, - for subtraction, * for multiplication, / for division, and ^ for exponentiation. See expression and calculated variable.

A synonym for dependent variable, usually paired with input.

In Tecplot 360, a drawing area that may contain multiple frames, each showing a view of a dataset. Tecplot 360 supports multiple pages; a new one is opened each time you view data from Tecplot Chorus, rather than opening a new instance of Tecplot 360. Pages can be managed using the Chorus sidebar.

A textual representation of the directories containing a file, used to specify the file’s location on the computer. An absolute path starts at the root of the file system (Linux), at the root of a particular local drive such as C: (Windows), or at the root of the network (also Windows). A relative path assumes starting at some other known directory (such as the user’s home directory or a project directory) and specifies the file’s location in the hierarchy "below" this directory.

A synonym for independent variable, often paired with result.

An application of CFD to design tasks such as optimization that require an exploration of a design space. Simulations are run with various combinations of parameters, or input variables, to find cases that meet or optimize the established design criteria.

A way to specify a filename that allows one to select more than one file without specifying the names of each individually. Wildcards may be used to match partial names. For example, when tagging files with Tecplot Chorus, case* matches any file whose name begins with "case", while *.png matches any PNG file.

A free file format for storing images, well-suited for reproducing crisp line art and text. Tecplot Chorus can export any image or plot in PNG format.

In Tecplot Chorus, projects are containers for related cases. Each case is represented by a record that stores the case’s variables. A separate location on your computer’s disk or a network share is used to store auxiliary files associated with each case. Tecplot Chorus plots and other views are derived from the cases in the project.

See root path.

Each plot and view of your Tecplot Chorus project has settings, referred to as properties, that determine its behavior and appearance. Each window (even different windows displaying the same kind of plot) has its own properties. The properties appear in the Properties panel, which initially appears at the left of the workspace but can be docked to any edge of the window you find convenient, or dragged outside the Tecplot Chorus workspace—even onto a second display.

See response surface.

After a surrogate model has been trained, Tecplot Chorus can ask it for predictions of output variables based on specific input values (query values), which may or may not represent actual cases in the project. This is called a query; the verb form is making a query or querying.

The input variable values used in a query to a surrogate model.

A filter that allows you to specify the first and last value of a variable that you wish to be included in your Tecplot Chorus views. Useful for variables with continuous values. A histogram is also displayed with this filter to give you an idea of the value distribution.

Specifies the query values to be used for input variables to a surrogate model when those values are being used on the plot. The low and high values are specified (the range) along with the number of values to be chosen between them (the sampling).

A path that specifies the directories containing a file relative to some directory, such as a user’s home directory or a project directory. Relative paths generally do not start with a drive letter or a slash.

An approximation similar to a curve fit, except in n dimensions. Tecplot Chorus can use a quadratic (second-order) response surface in a surrogate model. This is appropriate for modeling many physical phenomena because they are commonly at most quadratic.

A synonym for dependent variable or input, often paired with parameter.

A directory (folder) on your computer’s hard disk, or on a network file share, that contains the auxiliary files associated with a Tecplot Chorus project. These can include files created by your solver or generated in post-processing, as well as files created by Tecplot Chorus.

A tool that allows you to rotate 3D plots and literally see your project from another angle.

The process of creating a style template in Tecplot 360 for a single case, then using Tecplot Chorus to apply that template to the data files of multiple cases to generate an image or a layout package, and finally importing the generated images or data files into Tecplot Chorus.

A noun referring to a simulation being run using a particular combination of parameters or inputs. Some CFD engineers use this term instead of, or as a synonym for, case. In some circles, however, the term case is preferred, and run may have a slightly different meaning; for example, if you simulate the same case multiple times, you would have multiple runs, but still only a single case.

A Tecplot Chorus plot that places cases on a grid based on the values of two parameters. This plot is useful for revealing correlations between variables as well as for finding unexpected clustering of cases. Tecplot Chorus offers both 2D and 3D scatter plots.

Data (in Tecplot Chorus, cases) chosen for some future operation. Cases can be selected in any view of a Tecplot Chorus project, including plots. Once selected, the images or data files associated with the cases can be viewed and compared, new images or data files can be generated, and so on.

In Tecplot Chorus, a file that records the current project and all open views and their properties, including the locations and sizes of all windows. Opening the session file returns you to the exact place you were when you saved it. This capability can be used to record typical starting points for working with a project or to save your place from day to day.

The container for the Filters and Properties panels that initially appears at the left of the Tecplot Chorus windows. These panels can be docked to other edges of the window, however, or moved out of the Tecplot Chorus workspace entirely, even to a second display.

An approach to managing, interpreting, and visualizing the results of large CFD experiments being pioneered by Tecplot Chorus.

A filter that passes only cases where the selected variable matches a single value, useful for "slicing" through discrete values of a variable.

A software package that calculates a CFD simulation and produces a solution file that can be visualized by a tool like Tecplot 360, as well as generating aggregate results (such as the overall lift, drag, and pressure) that can be used to help organize the results in a tool like Tecplot Chorus.

An adjective that refers to a CFD experiment where not very many cases have been simulated relative to the size of the design space. Due to the time required to run simulations, most CFD experiments are sparse to one degree or another highly-dimensional experiments especially so, due to the geometric expansion in the number of cases as dimensions (variables) are added.

The line at the bottom of the Tecplot Chorus window that displays the name of the current project and information about any background jobs that are currently in progress.

A file saved from Tecplot 360 that records the visual appearance of the current plot. This can then be applied to similar data sets to produce a series of plots that can be easily compared to each other by eye. See style template.

A Tecplot 360 style sheet that is used in Tecplot Chorus to automatically generate images or layout packages for selected cases.

A mathematically-derived proxy of an experiment generated by correlating the inputs and outputs of cases that have already been simulated, which can be used to predict the values of cases that have not yet been simulated. If you think of it as an n-dimensional curve fit, you won’t be far off. A surrogate model can be generated much more quickly than running even a single additional simulation, making it a useful analysis tool despite its approximate nature. Tecplot Chorus supports surrogate models based on a response surface or Kriging.

In Tecplot 360, the Chorus sidebar can be used to synchronize styles (the plot appearance) from the selected case to other cases so that they are easily compared visually.

Generally, the grammar of a statement. In expressions such as the ones used for calculated variables in Tecplot Chorus, refers to the correct placement of symbols representing mathematical operations. For example, every addition operation must have two terms, one on either side of the + sign; every opening parenthesis must have a corresponding closing parentheses. If syntax rules are not obeyed, Tecplot Chorus cannot evaluate the expression.

A Tecplot Chorus line plot in which no lines are used to connect the cases. Instead, a symbol such as a square is plotted for each case. May be combined with a line plot so that it is clear where on the line the cases are, which may be difficult to determine for some kinds of data.

In Tecplot Chorus, a spreadsheet-like view in which each case is represented by a row, and each variable by a column. Shows the actual variable values for each case.

A short identifier (such as "Wireframe Image" or "Contour Data") that is used to identify an image or data file in Tecplot Chorus. Each tag has an associated pattern that is used to identify which files are selected by the tag, which may contain wildcards in case the files have not been named consistently. Tags for some kinds of data files may identify multiple files at once.

A way to manage related tags in the image viewer and the matrix view, allowing them to easily be turned on or off together. Also determines the order of tags when viewing by tag in either window.

see style template.

As a verb, to arrange windows so that they are all the same size and not overlapping, so you can easily find the one you want. Tecplot Chorus can tile windows with a single click of the mouse.

The row of buttons at the top of the main Tecplot Chorus window that allows you to perform a variety of functions with a single click.

The process of generating a surrogate model by analyzing the implicit correlations between input variables and output variables in a Tecplot Chorus project, allowing the model to make useful predictions for cases that have not been simulated.

To move a Tecplot Chorus plot within its window. In some plots this changes the axis range, which has much the same effect. So named because in either case, you are essentially changing its coordinates.

One of several named values associated with a particular case in a CFD experiment. Each case will have the same variables, but the values of each variable may differ for each case. The purpose of each variable is its variable nature.

In Tecplot Chorus, the purpose of a variable: independent (input or parameter), dependent (output or result), or other (informational fields, links to auxiliary files, and so on).

In Tecplot Chorus, any window that displays the cases in your project is a view, or a data view. This includes the matrix, the table, and all plots.

In Tecplot Chorus, the Recent Projects screen that lets you easily open projects you have been working with recently and create a new project with the click of a button. Choose View → Welcome Screen to see it.

A special character such as * or ? that can be used in a pattern to match any letter or number in a file name. For example, case* would match any file name starting with "case," while *.png would mean any file name ending with ".png".

The main part of the Tecplot Chorus application window where plot and view windows appear. Windows may be dragged out of the workspace, even to a second display.

The eXtensible Markup Language, a standardized, easily-extended text format for storing and exchanging data. Tecplot Chorus uses XML for loader description files, custom action registration and instruction files, and session files.

In Tecplot Chorus, the ability to magnify (zoom in to) or shrink (zoom out of) plots. In some plots, the axis ranges are changed instead; the intent is to display more or less data rather than literally making the plot larger or smaller.