two phase analysis of a bubble of air in water

Hi,

I have created a model (see attached) with an air bubble size 8mm in diameter inside a cube of water 17.5mm in size. this analysis converges.

When I create the same analysis but in um (meaning air bubble 8um in diameter in a cube of water size 17.5um) it doesn't converge.

Can someone guide me what parameters must I tweak to make this analysis to converge?