Given a vector field and I'd like to detect if there are streamlines in closed patterns. For example, if the input is a vector field like this:

```
image = ColorConvert[Rasterize[\[Infinity], ImageSize -> 40],"Grayscale"]
{dx, dy} = Table[ImageAdjust@GaussianFilter[image, {6, 2}, \[Delta]],
  {\[Delta], {{1, 0}, {0, 1}}}];
data = Reverse /@ Transpose[2 ImageData /@ {dx, dy} - 1, {3, 2, 1}];
ListVectorPlot[data, VectorPoints -> 30]

```

[![enter image description here](https://i.stack.imgur.com/CD2O6.png)](https://i.stack.imgur.com/CD2O6.png)

then I'd like to find these three streamline curves that I've drawn in red:

[![enter image description here](https://i.stack.imgur.com/8V7lt.png)](https://i.stack.imgur.com/8V7lt.png)

Detecting closed currents in a vector field seems very doable. I'm not sure if I should use autocorrelation.

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