I have used the (amazing) work done by @xzczd
In this question: How to solve a system of PDEs with zip condition?
in order to solve a similar problem. I ran into a problem to define S(0)=0 (same as in the attacked question). when i plot S(t) Vs time i see that in both my case and the example mentioned S(0) starts at x=1. Is there a way to change it to S(0)=0? Thanks, Ofek.
NDSolvehas automatically chosen $S(0)=1$. Now the code has been revised. Thanks for pointing out. – xzczd Oct 26 '18 at 11:34