Physics MSc/phd vs. Maths phd

[sam_p_r]

I'm doing my undergraduate course in physics and getting good grades and enjoying it, especially the theoretical side. I'm definitely going to do postgraduate study, but I'm tempted switch to maths to do applied mathematics (fluid dynamics, chaotic systems etc.).

Does anyone know much about job opportunities in the fluid dynamics area, and if its possible to go back into physics after doing a maths phd? It seems to me that there's not much difference between physics and maths in the 'chaos theory area anyway.

any info would be appreciated