Motion blur for fluid sim particles (Cycles)? I've got a fluid sim with pretty convincing motion blur by enabling vectors in the fluid domain and using a vector blur node in the compositor. this works nicely. 

I also have a fluid sim object of type Particle. Under its particle settings I chose Rendered and assigned a Metaball object as the dupli object. It renders OK.
However, I can't get motion blur working for the particles. 
I also tried enabling motion blur under the Cycles Render properties. 
My guess would be that for every frame, the baked fluid particles are loaded without reference to their positions in the previous frame. Thus, to Blender they appear to be perfectly stationary

Is there a way to make it work, or what would be the best workaround? (eg. rendering the particles to a separate layer and blurring that layer

Another possible workaround might simply to render a video. we are talking about fast moving tiny droplets, the video codec might blur them, though probably in an ugly way
This is currently not supported (as of v2.82 / 2020)

See https://developer.blender.org/T19527