  We study the three-dimensional clustering of velocity stagnation points, of
nulls of the vorticity and of the Lagrangian acceleration, and of inertial
particles in turbulent flows at fixed Reynolds numbers, but under different
large-scale flow geometries. To this end, we combine direct numerical
simulations of homogeneous and isotropic turbulence and of the Taylor-Green
flow, with particle tracking velocimetry in a von K\'arm\'an experiment. While
flows have different topologies (as nulls cluster differently), particles
behave similarly in all cases, indicating that Taylor-scale neutrally buoyant
particles cluster as inertial particles.
