This expression works, by pushing Y value of Anchor Point of a layer “away” by specified radius size.
You have to parent your layer to a master Null Control layer. This way, you can keep X at 0. Then “push out” Y value. It will help, if you center your Anchor Point in the middle of your layer. And center align your layer with Composition Center. Then parent it to master Null, which it has to be in Comp Center, too.
With those steps, this set up will work, as layers will “push away” from Null based on radius specified with a slider.