Length and Width of recirculation

Hi Dear All,
Can any one know how to calculate the width and length of recirculation region for flows around a circular cylinder.
I find some procedure but i don’t know it’s correct or not.

1.Using Matlab’s interp2 routine (with the option ‘cubic’) to get the computed data to a finer grid.
2.And then using Matlab’s contour routine to get points along the zero contour line.
3.Then from the vector of data that returns, need to measure the data.

Is this procedure is correct for getting such things. If any one some procedure how to get the wake and length of recirculation regions for flows around a circular cylinder will be highly appreciated.
Thanks and Good luck to every one.