I've been trying to run the Quick Smoke simulation And below is the result:



The smoke is confined to the cube.

I'm guessing there are parameters that I need to adjust but I have not made any changes to the default settings since installing Blender.

Any ideas how to fix this issue?

Thanks in advance.

Additional information:

When on loop it appears to extend above the cube occasionally and when I was tinkering with Physics/Behaviour/Density it actually flowed like it should for one cycle. This may have been coincidence as I've not been able to replicate it. Is this an indication that my computer is unable to simulate properly?
It seems that my computer wasn't able to handle 20fps and I managed to get the Quick Smoke simulation to run at 10fps &amp; even better at 8fps.

I made this adjustment under Frame Rate 'custom' on the bottom right here: