Condition parameters, conditions, and condition sequences

A condition parameter is a physical measure that defines the magnitude of boundary conditions or solution objects.

For example, a condition parameter might be the pressure between the first and second compressor stages in a gas turbine aircraft engine.

A condition is a set of numerical values for all the condition parameters at a given state or operating condition of the system.

For example, suppose you define the pressure between each compressor stage to be condition parameters. You can define the pressures between the compressor stages at the beginning of takeoff to be a condition. Other conditions might define the pressures at the end of the ascent, or at the end of level flight, and so on.

A condition sequence is a time history of conditions. When you define a condition sequence, you assign a time (in seconds) for each condition. Thus, a condition sequence is a discrete representation of a mission or duty cycle with sets of values for the condition parameters defined at time points throughout the mission or duty cycle. For the values of the condition parameters at all other times during the mission or duty cycle, the software linearly interpolates the values at the discrete time points.

For example, suppose you assign 10 seconds to the takeoff condition, 30 seconds to the end of the ascent, and 4500 seconds to the end of level flight. The duration between the takeoff condition and end of the ascent condition is 20 seconds. The duration between the end of the ascent and the end of level flight is 4470 seconds. For the value of the condition parameters at 20 seconds, the software interpolates the values at 10 seconds and 30 seconds. The number of increments within each time interval is determined by how you define the solution.

When you define condition parameters, you do so without regard to any one analysis type. For example, a condition sequence can include any combination of structural, thermal, or flow parameters. You can use this single condition sequence to define multiple solutions, including linear, nonlinear, transient, thermal, and so on in the same Simulation file. Thus, you can use a single set of condition parameters to define the boundary conditions and solution objects for all analyses.

If your company uses a standard format for defining condition sequences (such as a BDD file) or follows standard practices regarding missions and duty cycles, you can import this data to capture these practices in your analyses and ensure consistency across teams and platforms.

Graph of how three condition parameters vary between four conditions in a condition sequence.

Creating condition sequences

To create condition sequences, conditions, and condition parameters, you have the following options:

• Use the Condition Sequences command.

• Import a properly formatted XML or BDD file.BDD files are created by a third-party sequence editor.

You can view the condition sequences that are loaded into the simulation in the Condition Sequence Manager dialog box.

From the Condition Sequence Manager dialog box, you can also:

• Edit and delete condition sequences, conditions, and condition parameters.Note: When you delete a condition sequence that is assigned to a solution, in the Solution dialog box, in the Condition Sequence list, Invalid Condition Sequence appears.

• Copy condition sequences and conditions.

• Export condition sequences to a BDD file or an XML file.

• Identify the solutions where a condition sequence is used.

Creating solutions from a condition sequence

After you import or create a condition sequence, use the New Solution from Condition Sequence command to create a solution. This command:

• Creates steps, subcases, or time steps as appropriate for the selected solution type and the number and sequence of conditions in the condition sequence.

• Specifies the appropriate evaluation time or duration for each step, subcase, or time step.

Updating a solution with changes made to a condition sequence

After you change the conditions in a condition sequence, use the Update from Condition Sequence command to update the solution that was created by that condition sequence.

With the Update from Condition Sequence command you can:

• Add new time points to the condition sequence.

• Change the time values in the condition sequence.

• Remove time points from the condition sequence.

Defining boundary condition magnitude for condition sequence solutions

When you define a condition sequence, the software creates a table field for each condition parameter. Each table field contains the value of the condition parameter at each time point in the condition sequence.

The table fields that the software creates for each condition parameter do not appear under the Fields node in the Simulation Navigator. The software uses the field function to automatically create a locked expression for each table field. These expressions appear in the Expressions dialog box. The software assigns the names you used for the condition parameters as the names for these expressions.

For example, suppose you name a condition parameter pressure1. In the Expressions dialog box, there will be an expression named pressure1 that has a formula of fd(“sys_field(nn)”), where nn is a unique identification number the software assigns to the table field.

Because the expression that the software creates for each condition parameter is locked, you cannot edit them from the Expressions dialog box. To edit these expressions, you must edit the condition parameter values and time values from the Condition Sequence Manager dialog box.

When you define boundary conditions and solution objects for your model, you can specify their magnitude with the expressions the software creates for condition parameters just as you would with any other expression.

Where do I find it?

Importing, editing, or creating a condition sequence:

Application	Pre/Post
Prerequisite	A Simulation file as the work part and displayed part
Command Finder	Condition Sequences

Copying condition sequences

Application	Pre/Post
Prerequisites	A Simulation file as the work and displayed partAn existing condition sequence
Command Finder	Condition Sequences
Location in dialog box	Condition Sequences group→right-click a condition sequence→Copy

Creating a new solution from a condition sequence:

Application	Pre/Post
Prerequisite	A Simulation file as the work part and displayed part
Command Finder	Solution from Condition Sequence
Simulation Navigator	Right-click the Simulation node→New Solution from Condition Sequence

Updating an existing solution with updated condition sequence:

Application	Pre/Post
Prerequisite	A Simulation file as the work part and displayed partA solution that was originally created by the condition sequence.
Simulation Navigator	Right-click the active solution→Update from Condition Sequence

How do I

Export a condition sequence

Import a condition sequence

Create condition parameters

Create conditions

Create a condition sequence

Create a solution from a condition sequence

Update a solution from condition sequence changes

Learn more

Using a condition sequence to define a solution

Exporting and importing condition sequences

Using the Add new Condition Sequences From File command

Define a boundary condition magnitude with condition parameters

Plot a condition sequence

Look up more details

XML file format for condition sequences

Quick links

Command reference

Pre/Post video examples

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Condition parameters, conditions, and condition sequences, Simcenter 3D 2021.1 Series

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