Debris blockage of isothermal flow through fuel rod assembly explored by PIV

Particle Image Velocimetry (PIV) experiment on flow through a model of a nuclear fuel rod assembly of hexagonal symmetry. See the file "poster-CANUT-blokace.pdf" for general overview.
Working fluid: atmospheric air (pressure 96859 - 98359 Pa, temperature 23.4 - 25.0 °C, humidity 34.9 - 41.6 %).
Wind tunnel: test section of size 305 × 202 × 3000 mm, the rest is described here: doi 10.1063/1.5138636.
Geometry:
Spacer grid: file "Plastev-v4.scad" contains the spacer grid definition. The parameter LICH at line 1 switches the nodes of circle or star shape. In the test section, there are 4 grids of alternating LICH in distances of 75 cm. The diameter of rods is 42.2 mm (parameter DD on the line 3).
Plug for blocking: file "Plug.scad". This plug fits to both node types.
PIV data: file "Data-Blocked-U10ms.zip" contains the calculated velocity vectors. It is ordered into folders with name e.g. "10ms-BC1-z01", where 10ms means the effective air velocity U = 10 m/s, BC1 means blocking at the first grid at the node of the Circular shape (other is denoted S - star shape), z01 means the distance of measuring plane from the last grid in multiplies of the grid periodicity M = 59 mm. The individual csv files contain header and then since line 10 the actual data, first 2 columns are indices on the PIV lattice, then are their coordinates in mm, then there are 3 columns of the velocity components U, V and W in m/s.