A modeling tool for Laser-Induced Incandescence (LII)

Max Hofmann, Boris F. Kock and Christof Schulz

IVG, Institut für Verbrennung und Gasdynamik, University of Duisburg-Essen

This is the web interface for LIISim, a software to simulate LII signals as well as for fitting experimental LII signal traces in order to determine particle sizes. The energy and mass balance is solved for the heating of nanosized particles by a pulsed laser and subsequent cooling by heat conduction, evaporation and radiation. Different particle parameters can be individually set. The model is set up for soot only, though a modification to general particle materials will be possible in future.

The user can choose between monodispere and polydisperse particles. Different models for the heat conduction sub model can be chosen, i.e. the free molecular regime, the continuum regime and the transition regime. This enables the modeling of LII signals for low, atmospheric and high pressure. In the transition regime, the choice can be made between the heat conduction model of McCoy and Cha and the Fuchs model.

The energy and mass balance can be solved for single particles or for aggregates. The theory for aggregates includes the shielding effect of particles inside an aggregate, resulting in an effective particle diameter of the aggregate for heat conduction.

The data file of the simulation or the fit procedure can be downloaded. For the simulation, the time histories of the LII signal, the particle temperature, the particle diameter as well as the contributions of the different heat loss mechanisms are listed. For the fit procedure, the time histories of the experimental signal and the best fit as well as information on the fitting results are listed. The use of LIISim is free!

Click here for simulating LII signals:

Click here for fitting individual LII signal traces:


A description of the underlying equations of the different sub-models is given here:

If you use LIISim, please cite:

M. Hofmann, B. Kock, C. Schulz, "A web-based interface for modeling laser-induced incandescence (LIISim)", Proceedings of the European Combustion Meeting (Kreta, April 11-13, 2007),

For further information please contact Max Hofmann or Christof Schulz.

Please visit also the website of the LII community at

We would like to acknowledge: This material is based upon work supported by the Deutsche Forschungsgesellschaft (DFG). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the DFG. The authors would like to thank Wolfgang Bessler for his support in web interface programming.

This is LIISim Version 1.5 by Max Hofmann
Webinterface Version 1.5 by Max Hofmann
Last update: April 4, 2007