Project files (Files only work properly in 2.91): / 44944126
In this video, I'll go over one way to seamlessly loop a smoke simulation in Blender 2.9. I'll use OpenVDB to create the effect, meaning that there's no need to render it out and loop it in post. Keep in mind, though, that this is a more technically involved method. So, although it allows for more control and versatility, it's tougher to work with, much slower to render, and more likely to lead to technical issues and bugs. Some of these hurdles will also be addressed in this video.
This video took me a bit longer to make than I anticipated, so I'm sorry about that! This time, I decided to avoid making a more comprehensive tutorial, as Mantaflow is still going through some notable bug fixes and changes. Instead, I opted for something more "futureproof". OpenVDB allows for much easier control over the simulation. Before, I had to use collection instances to be able to duplicate smoke simulations across a scene, with no control over their timing and with max tolerance for bugs and crashes. There are still plenty of big problems with the implementation of OpenVDB in Blender (different attributes for a base smoke simulation than for one with "Noise" enabled, for instance), but, it's still a major upgrade.
My current PC specs (I recommend better than these):
16 Gb of RAM
Processor: Intel® Core™ i7-3770 @ 3.40 GHz
Graphics card: Nvidia GeForce GTX 650 Ti
Keep in mind that parts of this video are sped up, so this is not a good reference for the performance of my computer.