While studies on vegetated channel flows have been developed in many research centers, studies on jets interacting with vegetation are still rare. This study presents and analyzes turbulent jets issued into an obstructed cross-flow, with emergent vegetation simulated with a regular array of cylinders. The paper presents estimates of the turbulence diffusion coefficients and the main turbulence variables of jets issued into a vegetated channel flow. The experimental results are compared with jets issued into unobstructed cross-flow. In the presence of the cylinder array, the turbulence length-scales in the streamwise and transverse directions were reduced, relative to the unobstructed crossflow. This contributed to a reduction in streamwise turbulent diffusion, relative to the unobstructed conditions. In contrast, the transverse turbulent diffusion was enhanced, despite the reduction in length-scale, due to enhanced turbulent intensity and the transverse deflection of flow around individual cylinders. Importantly, in the obstructed condition, the streamwise and transverse turbulent diffusion coefficients are of the same order of magnitude. See the paper: Mossa, M., Ben Meftah, M., De Serio, F. et al. How vegetation in flows modifies the turbulent mixing and spreading of jets. Sci Rep 7, 6587 (2017). https://doi.org/10.1038/s41598-017-05881-1

A subsequent investigation into jets interacting with an array of rigid stems was conducted by Mossa M., Goldshmid R.H., Liberzon D., et al., titled Quasi-Geostrophic Jet-Like Flow with Obstructions (Journal of Fluid Mechanics, 2021; 921:A12, doi:10.1017/jfm.2021.501). This study delves into the complex dynamics of quasi-geostrophic jet-like flows in the presence of obstructions, emphasizing the interplay between detrainment processes and the Coriolis force. Jet-like flows, prevalent in atmospheric and oceanic systems, are significantly influenced by background rotation and physical barriers, such as vegetation or engineered structures. The research aims to elucidate how these factors affect flow stability, momentum transfer, and turbulent mixing.

Detrainment, defined as the expulsion of fluid from the jet’s turbulent core into the ambient environment, plays a pivotal role in modulating mass and momentum fluxes. The study reveals that detrainment becomes particularly pronounced in the vicinity of obstructions, where localized flow separations and enhanced mixing layers are observed. This process alters the kinetic energy distribution, accelerating the decay of jet velocity and disrupting structural coherence over downstream distances.

The Coriolis force, a product of Earth's rotation, further modulates jet behavior by inducing lateral deflections. This deflection generates curved jet trajectories, with curvature intensity governed by the Rossby number—a dimensionless parameter reflecting the balance between inertial and Coriolis forces. The interaction between Coriolis-induced effects and detrainment fosters intricate flow patterns, including secondary circulation cells and asymmetric velocity distributions across the jet profile.

Theoretical models derived from momentum conservation principles account for the combined influences of drag, detrainment, and rotational dynamics. These analytical frameworks predict the evolution of jet velocity, characteristic length scales, and centerline trajectories. Validation was achieved through controlled experiments conducted on the Coriolis rotating platform at LEGI-Grenoble, allowing for precise flow parameter measurements under varying rotational conditions.

Experimental findings corroborated the theoretical predictions, demonstrating that both detrainment and the Coriolis force significantly govern jet dispersion. Detrainment was observed to intensify near obstructions, leading to rapid momentum loss and broader flow spreading. Concurrently, the Coriolis force induced notable curvature in the jet path, with deflection magnitudes increasing proportionally to rotational strength.

In conclusion, the study underscores the critical roles of detrainment and the Coriolis force in shaping quasi-geostrophic jet-like flows. These insights are vital for the accurate modeling of geophysical and industrial fluid systems, including oceanic currents, atmospheric jets, and environmental engineering applications.