Dear Dipen,
Thank you for the print screen. Apparently, the problem is generated by the instability of the model. I observed that you have many warnings which indicate strong oscillation in the model. My opinion is that the eror "Floating point division by zero" is just a consequence of the instabilities.
Recommendations:
1. Analyse the results file (it should cover 67% of simulation period) and try to identify the problems here;
1. Check out the geometry of the cross sections and the junctions between branches;
2. Try smaller time steps for simulation: 1 min, 30 sec, even 5 sec;
Best regrds,
Aurelian