This mini app, FFB-MINI, is based on a general purpose thermal flow simulation program FrontFlow/blue (FFB), being developed by Institute of Industrial Science, the University of Tokyo. FFB solves the unsteady incompressible Navier-Stokes equations by finite element method. FFB is MPI parallelized with domain decomposition. Although not using thread based parallelism explicitly, the current version of FFB includes optimizations for the K computer with the automatic thread parallelization functionality.