Without any broad announcement (yet, probably), NVIDIA has released a Unreal Engine 4 custom source code branch with the integration of the completely new GPU fluid solver called Cataclysm.
Update: as confirmed by the developers, Cataclysm solver is based on DX Compute shaders, not CUDA
The Cataclysm uses a custom FLIP based GPU solver combined with Unreal Engine 4’s GPU Particles with Distance Field Collisions. Cataclysm can simulate up to two million liquid particles within the UE4 engine in real time.
A FLIP (Fluid-Implicit Particle) solver is a hybrid grid and particle technique for simulating fluids. All Information for the fluid simulation is carried on particles, but the solution the the physical simulation of the liquid is carried out on a grid. Once the grid solve is complete, the particles gather back up the information they need from the grid move forward in time to the next frame.
To get access to the UE4 source code branch with Cataclysm integration few steps are required:
1) Create UE developer account and link it with your GitHub account as described here
1.1) It may also be required to link your NVIDIA GameWorks developer account to GitHub as well (guide)
2) Get the CataclysmDemo branch from NVIDIA repository at github.com/NvPhysX/UnrealEngine