if you didn't found anything
I recommend you the fallowing papers:
http://liu.diva-portal.org/smash/get/diva2:324983/FULLTEXT01
Here they are showing some kernel functions
also a paper with a different (hack) approach that is easier to implement...
Hi, I've started to write a simulator for SPH, and I'm fallowing a paper on SPH simulation,
The problem is that in that paper they show the formulas for computing force but they don't tell you on what vector do you need to apply this force.
So here are the formulas for pressure, viscosity...