We are missing a bit of context here, but as I understand, It is a way to insist there are some forces "actives", not just any type of force.
I suppose several types of forces were mentioned earlier in the text/speech, then "active" ones and it's a way to insist on those latter ones being present in this flux perpétuel.
One could have also said :
- (...), il y bien des forces "actives" .
- (...), il y a effectivement des forces "actives".
I must say it's a "spoken style" sentence, and depending on the intonation of speaker, it could also imply there are a lot of active forces.
Compared to the original sentence, a non-pleonastic variant looks like a plain boring description to me (physics school book's style) :
Au sein de ce flux perpétuel, il y a des forces "actives".