How to get specific guidance from busy advisor?
Your advisor will not solve your problem - at least it is very unlikely! Digging very deep in the specifics of such a simulation is something a person in such a position just don't have the time to - and sometimes even not the detailed knowledge, e.g. regarding frameworks used, implementation details etc.! 

One question you should adress is: Will (s)he accept negative results? If you can describe all steps you did, explain why things did not work as planned, do you still have a chance for a good grade? If "yes", then really everything is fine, you "just" have to work hard and document all your attempts.

If "no", you should try to get help from a graduate student or post-doc working in a similar field. But still keep your advisor updated about everything you do.