Contour plot problem

I am making a contour plot of the flow arount a oval. Each time I run it however, the plot contains 2 vertical lines that created discontinuities in the streamlines. Does anyone know how to get these to go away.

      [x,y]=meshgrid(-3:0.01:3);
      U = 10;
      msource = 1;
      a = .5;
      psi = U.*y+msource.*atan(y./(x))-msource.*atan(y./(x-2));
      figure
      contour(x,y,psi,50)

Answer 1

[Fangjun Jiang]

It is not a vertical line. If you change the meshgrid, you'll see.

[x,y]=meshgrid(-3:0.1:3)