Investigation of fibre-like shaped particles in a turbulent jet-in-crossflow channel flow configuration

• Successful application of image shadowgraphy in a wall-bounded water jet-in-crossflow channel configuration. • Measurements for vertical profiles of fluid (tracer particle) and fibre velocities, as well as fibre orientation and concentration within vertical planes were obtained. • In the near-wall region, the orientation PDFs showed three slightly higher probabilities for orientation angles of 30°, 70° and 150°. • Fibre orientation after wall rebound showed the highest probability for a fibre orientation angle of 30°. • Comprehensive modelling of elongated particle dynamics for the purpose of predicting dispersion in the studied configuration. Detailed experimental and numerical investigation of fibre-like particle dispersion in a horizontal jet-in-crossflow water channel is presented. Rigid glass fibres (mean diameter of approximately 40 μm, modal aspect ratio around 4) were injected through a small jet into a developed turbulent channel flow at various Reynolds numbers. Planar shadow imaging combined with Particle Tracking Velocimetry (PTV) enabled simultaneous measurement of tracer-based flow field, and fibre velocities and orientations. The study covered three cross-flow velocities, capturing different jet penetration behaviours and fibre-wall interactions. Complementary Euler/Lagrange simulations were performed for one representative case to reproduce and better understand the flow field and fibre dispersion. The modelling framework, which includes non-spherical particle transport and a modified wall collision model, enabled analysis of sub-model contributions and comparison with experimental data. The measurements revealed strong dependence of jet penetration and fibre dispersion on the cross-flow velocity, with substantial changes in fibre trajectory and lateral dispersion observed at higher velocities. Fibre velocities at the jet edges exceeded local fluid velocities due to vortical structures, and the orientation statistics showed broad angular distributions, with some preferential alignment dependent on wall proximity and jet dynamics. Numerical calculations agreed well with flow profiles and fibre velocities near the jet-wall interaction region, but underpredicted dispersion and orientation further downstream. These discrepancies highlight the need to refine wall interaction modelling and account for fibre polydispersity and turbulence effects. The dataset and modelling approach together provide a valuable benchmark for validating fibre transport simulations in jet-in-crossflow wall-bounded liquid flows. Three typical image series for fibres colliding with the bottom wall of the channel