Global Variable

Introduction

Text.

Property Grid

General

Initial Value

Data Source

Definition

None

Fluid

Definition

Reduction

Definition

Minimum

Maximum

Sum

Mean

StdDev

RelStdDev (10%)

Interval Option

Definition

Every Time Step

Custom Interval

Global Variable UDF

depends on UDF expression | This UDF defines the custom field variable to be calculated as part of the global variable reduction. One output must be defined within the UDF: a floating-point variable named value. The values calculated by this UDF are fed into the reduction operation. This can be either a voxel-based or a particle-based local UDF, depending on the data source.

Particles

Definition

Data Source Particle Name

TBA

Massless Tracers

Inertial Particles

Reduction

TBA

Minimum

Maximum

Sum

Mean

StdDev

RelStdDev (10%)

Interval Option

TBA

Every Time Step

Custom Interval

Global Variable UDF

depends on UDF expression | This UDF defines the custom field variable to be calculated as part of the global variable reduction. One output must be defined within the UDF: a floating-point variable named value. The values calculated by this UDF are fed into the reduction operation. This can be either a voxel-based or a particle-based local UDF, depending on the data source.

Probe

TBA

Data Source Probe Name

Interval Option

TBA

Every Time Step

Custom Interval

Global Variable UDF

depends on UDF expression | This UDF defines the custom field variable to be calculated as part of the global variable reduction. One output must be defined within the UDF: a floating-point variable named value. The values calculated by this UDF are fed into the reduction operation. This can be either a voxel-based or a particle-based local UDF, depending on the data source.

Interfaces

TBA

Reduction

TBA

Minimum

Maximum

Sum

Mean

StdDev

RelStdDev (10%)

Interval Option

TBA

Every Time Step

Custom Interval

Global Variable UDF

depends on UDF expression | This UDF defines the custom field variable to be calculated as part of the global variable reduction. One output must be defined within the UDF: a floating-point variable named value. The values calculated by this UDF are fed into the reduction operation. This can be either a voxel-based or a particle-based local UDF, depending on the data source.

Time

TBA

Global Variable Time UDF

user-defined units | This UDF defines how the global variable changes over time. This option is relevant when the Data Source is set to Time. This is a System UDF.

Download Sample File: Global Variable Time

Stats Value

TBA

Stats Selection

Static Body

TBA

Data Source Static Body Name

Static Body

Reduction

TBA

Minimum

Maximum

Sum

Mean

StdDev

RelStdDev (10%)

Interval Option

TBA

Every Time Step

Custom Interval

Global Variable UDF

depends on UDF expression | This UDF defines the custom field variable to be calculated as part of the global variable reduction. One output must be defined within the UDF: a floating-point variable named value. The values calculated by this UDF are fed into the reduction operation. This can be either a voxel-based or a particle-based local UDF, depending on the data source.

Property Link

TBA

Property Link

Property Value

Signal

Signal Enabled

Signals will write the global variable at the specified interval.

Off

On

Text.

Signal Start Time

s | Text.

Signal End Time Option

Options.

End of Simulation

Specified

Text.

Signal End Time

s | Text.

Signal Sampling Interval

s | Text.

Display Name, Unit

Display Name Override

Display Unit Override

Legacy Text:

Each global variable is a single value that is globally available in all user defined functions. The value may be computed by the following methods:

  1. No Calculator – The value is set by one of the UDFs

  2. Fluid – The value is computed from a reduction on the Fluid cells

  3. Particles – The value is computed from a reduction on the particles set

  4. Probe – The value is set by a probe value

  5. Interfaces – Like the Fluid, but the reduction is limited to those cells that contain the free surface

  6. StatsSelection – Select a value from the statistics to use the statistics at runtime

Reductions

A reduction is an operation that takes in many values and computes a single value. These are the available reductions:

  1. Minimum

  2. Maximum

  3. Mean

  4. Sum

  5. Standard Deviation

  6. Relative Standard Deviation

Evaluation Region

By default, global variables are reduced over the entire domain. By appending children geometry objects, you can limit the region of evaluation. So for example, if you add a Box geometry as a child to the global variable, the global variable will only operate on the internal cells within the box.

Examples

Set value to maximum fluid velocity. At runtime this UDF is evaluated over the fluid cells. The value is set to the fluid velocity magnitude. The maximum is then taken of all the values, returning the maximum velocity magnitude into the global variable value. This global variable can then be used by any other UDF.

  • Set the Data Source = Fluid

  • Set the Reduction = Maximum

  • Set the code expression to:

    value = v;