I was recently investigating how to reduce that blockiness you get around smoke emitters. I did several tests with it and was so amazed about the results that it frankly makes me feel stupid for not realizing there was something wrong earlier.
Previously high resolution flow voxels were generated based on the low resolution ones. So if you had 32 simulation base resolution and 4 division high resolution, it still used smoke flow generated from those 32 resolution voxels. Now I introduced a new sampling method called "Full Sample" that generates full resolution flow for for high resolution domain as well.
You can enable "Full Sample" in smoke high resolution panel. That menu also includes old "Nearest" and "Linear" interpolation settings for smoke flow in order to keep old files compatible. Full sample is default in new simulations though.
Here is a comparison between old and new high resolution smoke:
Left suzanne is the low resolution version (32 res). Then the old (4 division) high resolution flow. Last one is the new "full sample" version using otherwise same settings.
Another comparison with a complex mesh flow:
Again, left is the old 32 res 4 high division simulation. Right image is same setup with full sample flow.
One problem especially with fire simulations has been that the fluid motion usually looks good with fairly low resolutions. However it has been necessary to increase the resolution anyway, in order to get rid of those blocks. Not anymore. It's also much easier to create thinner layer of smoke around the emitter. Not to mention higher detail when using textures as flow masks. :)
I made couple of new fire demos inspired by the possibilities of block-free smoke flows: