Transient thermal analysis

In contrast to stationary temperature field simulation, transient temperature field simulation also records the temporal changes in the state variables. In addition to thermal conductivity, density and specific heat capacity are also included in the calculation.

If the time or speed of a temperature change and the resulting temperature fields are relevant for the component evaluation, a transient analysis must be performed.

Computation time / model size

As in structural mechanics, transient analysis in the time domain is much more time-consuming than static or stationary analysis in temperature field simulation.

Since a temperature change can be microscopically observed very quickly, the step size for the simulation depends strongly on the task. If the temperature curve in thin layers is of interest, for example as in the case of a piston in an internal combustion engine, much shorter time steps and smaller elements must be used. According to the calculation goal, this results in very different requirements for the mesh resolution and computation time.

If the structure under consideration is subjected to a sudden load change, an exponential approach to the final stationary state results at every point. As the temperature changes become smaller and smaller over time, the step size can be increased accordingly as the simulation progresses.

Relevance

The temperature fields obtained often serve as a model description for a subsequent structural simulation. This refers both to the local, temperature-dependent material properties and to the resulting thermal expansion.

Transient temperature field simulation is of great relevance in many areas. For example, the observation of thermomechanical fatigue processes would not be possible without precise knowledge of the local and temporal temperature curve. Even in simpler applications, it is often without alternatives.