c=2;l=200; modell={u'[z]==v[z], v'[z]== - c v[z] - u[z] (1 - u[z]), u[0]==0.999, v[0]==-0.001}; loesung=NDSolve[modell,{u,v},{z,0,l}]; uu[z_]:=If[z>0,u[z]/.loesung[[1]],0.999]; abb=Plot3D[uu[x - c t],{x,0,100},{t,0,20}, PlotPoints->30,PlotRange->All, ImageSize->{400,300},AxesLabel->{"x","t","w"}];