SOLVERS Home: Initial Conditions (Transient Heat)

Description

Two options are available to define the initial conditions for the Transient Heat solver:

Applied Nodal Temperature; and
From File.

Applied Nodal Temperature

If set, the initial nodal temperature for the transient heat analysis is defined by nodal temperature attributes in the Load Case for Node Temperature setting specified in the SOLVERS Home: Case Dependence section.

From File

Initial Conditions File

Selects a previously generated results file (the initial file) to be used as the initial conditions for the transient heat analysis. Any result case from the initial file can be used as the initial case.

There are a number of uses for this feature, including the following:

To extend a previous transient heat analysis by appending new result cases to the same result file.
This requires that the name of the result file specified in SOLVERS: Files be the same as the name of the initial file. If the result case used as the initial case is the last one in the initial file, the additional result cases are appended to the initial file. If the result case used as the initial case is not the last case in the initial file, all result cases after the initial case will be deleted and the new additional result cases will follow the initial case in the initial file.
To extend a previous transient heat analysis by saving the new result cases to a new result file.
This is similar to the previous use except that the new result cases are not appended to the initial file but saved to a new file. This requires that the name of the new result file specified in SOLVERS: Files be different from the name of the initial file. The new result cases are saved to the specified result file overwriting that file (there is no option to append to that file when it is a different name from the initial file).
To start a transient heat analysis using a steady state heat analysis as the initial conditions.
The results in the selected result case of the initial file are used as the initial temperature distribution for the transient solution. This is taken to be the temperature distribution at time zero. The results of the transient heat analysis are stored in the file specified in SOLVERS: Files, overwriting that file.

Override applied temperature attributes

This option is applicable when a steady heat or transient heat solution is used as the initial conditions for a transient heat analysis.

If set, node temperature attributes are ignored, starting with the current time step, and the temperature at all nodes is initialised according to the selected result case in the initial conditions file. All nodes are now active degrees of freedom in the analysis, allowing their temperature to change with each time step. The Load Case for Node Temperature setting specified in the SOLVERS Home: Case Dependence section is effectively ignored.

If not set, nodes without temperature attributes will be assigned initial temperature values from the selected result case in the initial conditions file, starting with the current time step. Nodes with temperature attributes will continue to use the assigned attributes according to the Load Case for Node Temperature setting specified in the SOLVERS Home: Case Dependence section, and therefore the temperature at these nodes continues to be controlled by the attribute.

Time Steps

This option is applicable only when a transient heat solution is used as the initial condition file.

Append remaining time

Time steps defined in the time table (SOLVERS: Time Steps) that represent a time earlier than the time instance of the result case used as the initial case are skipped. Time steps that represent a time after the time instance of the initial case are added. For example, if the initial case represents time=25 s, and the table defines 50 steps of 1 s, at the completion of the analysis the result file will contain result cases up to an including time=50 s. In the case where the maximum time in the time table represents a time less than or equal to the time instance of the initial case, no further result steps will be produced.
Append all time steps

Time steps defined in the time table (SOLVERS: Time Steps) are added to the time instance of the result case used as the initial case. For example, if the initial case represents time=25 s, and the table defines 50 steps of 1 s, at the completion of the analysis the result file will contain result cases up to and including time=75 s.