Recently Next Limit Technologies released a version of RealFlow that works within Cinema 4D. RealFlow C4D gives you all the benefits of RF directly in Cinema 4D. This means that you no longer have to bounce around back and forth between both applications to create amazing fluid simulations.
If you want to have a look at how RealFlow C4D has to offer, and how it works, here, Brandon Clements offers up a little insight into creating a simulation. Brandon walks through creating caramel drizzle over top of chocolate using RealFlow C4D, and Octane Renderer 3 for rendering.
RF for C4D offers another great option for creating fluids. There is also Turbulence FD from Jawset, which some say has the advantage with GPU acceleration. Whichever you think is best, it’s interesting to see Cinema 4D have this kind of integration, making complex FX workflows much easier.