Initial conditions in Transient thermal: overview

Transient application: reminder

A transient application is a physical application characterized by:

  • properties that vary in function of time: variable sources, variable material characteristics…
  • a time equation (differential equation of the 1st order) : d/dt ≠ 0 (transient regime or variable regime).

The resolution consists of a sequence of resolutions in time. The solutions are not independent from each other: each solution is linked to the previous one by the temporal equation.

General case

In the most general case, the state variable (the temperature) is initialized at a predefined initial value Tinit (pour t = 0). The1st time step (t = t1) corresponds to the first Flux solving, as shown in the table below.
  Initial instant 1 st time step
Flux Solver t = 0 t = t1  
Temperature T0 = Tinit T1 = Tcomputed  
Note: The value of the initial temperature is defined at the level of the solving options.

Particular case

It is possible to start a new transient thermal computation by using as initial state the result of a Steady State Thermal application or of a Transient Thermal application.

This permits, for instance, to resume a computation after the modification of the values of a physical quantity (convection coefficient...)