Transient Analysis Tab (Automatic)

Solvers

Notes

Stress analysis
Piezoelectric Analysis
Thermal Analysis

Acoustic Analysis

Fluid Analysis

Specify [Finish Time] or [Maximum Number of Calculation Steps] before analyzing.

Solvers each set its proper timestep automatically.

The calculation continues until the finish time is reached; however, the calculation is aborted when the maximum number of calculation steps is reached.

• If the calculation is aborted at the maximum step, the restart-enabled solver can restart from the step.

• The automatic timestep setting is specified in detail with [Detailed Automatic Timestep Setting].

Each solver determines its timestep as follows.

Thermal Analysis:

If [Adjust referring to time-dependent condition] is selected in [Detailed Automatic Timestep Setting], the timestep is calculated based on the time dependency (Weight Function) of the heat source or the frequency of the voltage waveform in the electric-thermal analysis.

When the waveform is input, the timestep is defined as one cycle divided by 12. To change the number of divisions, select [Change the number of divisions per cycle].

If [Adjust referring to time-dependent condition] is not selected in [Detailed Automatic Timestep Setting], the timestep is calculated based on the body size and the thermal diffusivity inside the body.

[Transient Analysis Using Resonant Mode] not selected in the stress and piezoelectric analyses:

If [Adjust referring to time-dependent condition] is selected in [Detailed Automatic Timestep Setting], the timestep is calculated based on the weight function of displacement or voltage.

If [Adjust referring to time-dependent condition] is not selected in [Detailed Automatic Timestep Setting], the timestep is calculated based on the body size or the elastic wave speed inside the body.

In [Detailed Automatic Timestep Setting] with [If non-convergence, set a finer timestep] selected, if a calculation does not converge, set the timestep finer and redo the calculation.

[Transient Analysis Using Resonant Mode] selected in the piezoelectric analysis:

[Adjust referring to time-dependent condition] will be automatically selected in [Detailed Automatic Timestep Setting].

The timestep is calculated based on the results of resonant frequencies in the resonant analysis or the time dependency (Weight Function) of voltage or displacement .

One cycle is calculated based on the maximum resonant frequency. The timestep is defined as one cycle divided by 10. To change the number of divisions, select [Change the number of divisions per cycle].

Explicit method is used in the acoustic analysis:

[Adjust referring to Courant number] will be automatically selected in [Detailed Automatic Timestep Setting].

The timestep not incurring numerical instability is calculated based on the Courant number (CFL number) that is determined by the mesh size and sound speed.

Implicit method is used in the acoustic analysis:

[Adjust referring to time-dependent condition] will be automatically selected in [Detailed Automatic Timestep Setting].

The timestep is calculated based on the frequency of the input waveform of the speed boundary condition or other conditions.

When the waveform is input, the timestep is defined as one cycle divided by 20. To change the number of divisions, select [Change the number of divisions per cycle].

Fluid Analysis:

If [Adjust referring to time-dependent condition] is selected in [Detailed Automatic Timestep Setting], the timestep is calculated based on the time dependency (Weight Function) of the flow velocity.

If [Adjust referring to Courant number] is selected in [Detailed Automatic Timestep Setting], the timestep is calculated such that the flow travel distance per time meets the requirement associated with the specified Courant number.

In [Detailed Automatic Timestep Setting] with [If non-convergence, set a finer timestep] selected, if a calculation does not converge, set the timestep finer and redo the calculation.

• For the free surface analysis (VOF Method) with the automatic timestep setting, the [Adjust referring to Courant number] option and the Courant number of 1 or less are recommended.
  For other analyses with the [Adjust referring to Courant number] option selected, the Courant number of about 10 is recommended.
  

• For the detail of [If non-convergence, set a finer timestep], refer to the corresponding help menu of the [High-Level Setting Tab].

In some cases, the automatic timestep setting may not be appropriate. If the automatic calculation is not satisfactory, select [Manual] instead of [Automatic] to try the manual entry.

Selecting [Specify the output interval] and specifying the interval can limit the output result and downsize the result file.

If 10 is specified, the result is saved in a file every ten times.

Click the Table button. The Time Table window will appear.

You can see the relationship between time and the weight function that is set on the mechanical tab, thermal tab, electric tab of boundary conditions, or the heat source tab of body attributes.
See [Weight Function Setting] for the table.

Magnetic Transient Analysis (By default)

Specify [Number of Cycles] before analyzing.

* Magnetic-transient analysis is available in an optional package.

The timestep is defined as one cycle divided by 12.

If [Change the number of divisions per cycle] is selected, the default number of divisions can be changed.

Selecting [Specify the output interval] and specifying the interval can limit the output result and downsize the result file.

If 10 is specified, the result is saved in a file every ten times.

Magnetic Transient Analysis
[Rotating Machinery, Constant Rotation Speed]

It is available when [Constant Velocity] is selected for the rotational movement on the [Rotating Machinery] tab in the rotating machinery analysis of the magnetic transient analysis.

* Magnetic-transient analysis is available in an optional package.

Specify [Number of Steps] before analyzing.

The rotating machinery moves rotationally by (Circumferential Division Angle) * (Rotation Quantity per Step) of the [Rotating Machinery] tab per step.
Time per step is obtained by (Circumferential Division Angle)*(Rotational Quantity per Step)/((Number of Rotations)*360/60) [s].

Selecting [Specify the output interval] and specifying the interval can limit the output result and downsize the result file.

If 10 is specified, the result is saved in a file every ten times.

• If [Output motor characteristics file] is selected on the MATLAB/Simulink tab in the magnetic transient analysis, the timestep will be as follow.
  
  The number of steps automatically calculated as below.
  If [Timestep] is not integer, an error occurs, and the calculation will not be performed.
  
  (Number of steps) = 360 / (number of pole pairs) / (mechanical angle per step) / 3
  
  The rotating machinery moves rotationally by (Circumferential Division Angle) * (Rotation Quantity per Step) of the [Rotating Machinery] tab per step.
  Time per step is obtained by (Circumferential Division Angle)*(Rotational Quantity per Step)/((Number of Rotations)*360/60) [s].

Magnetic Transient Analysis (Translational Machinery)

It is available in the translational machinery analysis of the magnetic transient analysis.

* Magnetic-transient analysis is available in an optional package.

Specify [Number of Steps] before analyzing.

The translational machinery moves translationally by (Division Size in Traveling Direction) * (Traveling Quantity per Step) of the [Translational Machinery] tab per step.
Time per step is obtained by (Division Size in Traveling Direction) * (Traveling Quantity per Step)/(Moving Speed) [s].

Selecting [Specify the output interval] and specifying the interval can limit the output result and downsize the result file.

If 10 is specified, the result is saved in a file every ten times.

Electromagnetic Analysis
(Not Coupled with Thermal Analysis)

This is available for the electromagnetic-transient analysis.

*Electromagnetic-transient analysis is available in an optional package.