function [ux,uy] = path_lines_vel(x,y,t)

%---
% evaluate the velocity
%---

 Omega=1.0;
 G = 0.5;
 alpha=0.0;

 ux = G*x-Omega*y+0.5*alpha*x*exp(-t);
 uy = Omega*x-G*y+0.5*alpha*y*exp(t);

%---
% done
%---

return