Problem on simulating (polimi) soot model

From your log file it is evident that the local ODE solver is not able to solve correctly the chemistry. A possible explanation is related to the different names of species when you move from the GRI mech to the POLIMI mech. Let me better explain this point. The POLIMI mechanism is larger tha the GRI, so in principle you expect that all the species available in the GRI are also present in the POLIMI. This is reasonable to imagine, but not necessarily true. Moreover, the same species can have different names in the 2 mechanisms. In both cases (a species in GRI in not present in POLIMI and/or different names) there is a numerical problem: when you move the solution from GRI to POLIMI you loose the mass associated with the missing species. If the mass loss is relatively small. laminarSMOKE can manage, by replacing the missed mass with nitrogen. However, if the lost amount is large, numerical issues arise. Thus, the first option is to check if this is the case, i.e. if there are no issues in transferring the solution from GRI to POLIMI and to be sure that the same species have the same names.
A second option, which is convenient to use more in general when you change the kinetic mechanism, is the follwoing: instead of start solving the whole system of equations (momentum, temperature and species), it is better to proceed gradually, by freezing first the momentum and the temperature equation (i.e solving only for species), then enabling the temperature, and then the momentum too.