After gaining more experience with ASL I'm convinced that it is the best accelerated open source LBM-solver as of end of 2015. It has following important advantages:
- simple C++ API (and only C++ - no need to know OpenCL or Python)
- multiphysics: many other physical/chemical phenomena beside LBM
- hardware accelerated, can be deployed on CPU/GPU/FPGA/DSP/APU
- mesh-free, immersed boundary technology allows to move from CAD directly to simulation (important for automated design optimization).