Nucleation simulations using the fluid dynamics software FLUENT with the fine particle model FPM.

This work is an assessment of the capabilities of the FLUENT-FPM software package to simulate actual nucleation experiments. In the first step, we verified the FPM condensation routine with the NEWALC code. Next, homogeneous nucleation of n-butanol, n-pentanol, and n-hexanol in a laminar flow diffusion chamber (LFDC) was simulated and the results were compared to experimental data and an earlier model, which was described by Lihavainen and Viisanen (2001) and will be called femtube2 in the following. Models based on classical nucleation theory typically give too small nucleation rates for alcohol vapors. Also, the FPM underestimates particle production by several orders of magnitude, the factor being a constant for each nucleation isotherm (i.e., at constant nucleation temperature). However, experimental observations beyond exact particle concentrations can be reproduced. We found a behavior similar to the experiment for the dependence of the concentration of nucleated particles N on the flow rate. After correcting the FPM nucleation rate by a constant factor, experimentally found vapor depletion effects could be simulated. Comparing the FPM and femtube2, we observed that the FPM systematically predicts lower saturation ratio values. Further investigation of vapor depletion showed significant differences between the FPM and the femtube2 model. Furthermore, FPM simulations confirm the earlier found carrier gas effect (Lihavainen and Viisanen, 2001).