(* suppose a finite element run generated a solution u[x,y] with the \ command listed below*)
ufun = NDSolveValue[{op ==
Subscript[\[CapitalGamma], N1] + Subscript[\[CapitalGamma], N2] +
Subscript[\[CapitalGamma], N3], Subscript[\[CapitalGamma], D]},
u, {x, y} \[Element] mesh];
(* and suppose at constant value y=ycon, the command below \ sucessfully plots the solution u[x,ycon] vs x *)
Plot[Re[ufun[x, ycon]], {x, xlow, xhigh}, PlotLabel -> "ycon=0 Real u vs x " ]
(* QUESTION:
HOW TO EXPORT THE u[x,ycon] vs x PLOTTED CURVE AS A SIMPLE Nx2 two \ column data FILE *)