grid refinement
 

I have a quadratic grid mapped onto a circle in 2d in a so that it appears radial (if that makes sense) and I am trying to refine it to capture a shock wave. However when I refine it fluent adds one "rim" to the area and several "spokes". I would like to know if there is any way I can add several "rims" to get a sharper shock without ending up with loads of unneccessary nodes along the shock chewing up processor power? I realise I haven't explained well but if anyone has a clue what I'm on about I'd appreciate the input