ASCE has honored Adel Emadzadeh and Yee-Meng Chiew, Ph.D., M.ASCE, with the 2021 Karl Emil Hilgard Hydraulic Prize for the paper “Settling Velocity of Porous Spherical Particles,” published in the January 2020 issue of Journal of Hydraulic Engineering

The paper presents very detailed experimental observations of the flow surrounding porous particles, with the aim of defining the settling velocity for this type of particle. To that end, the authors use the modern techniques of Particle Tracking Velocimetry (PTV) and Particle Image Velocimetry (PIV). Although this is a classic problem of fluid mechanics, there is a need for these kinds of detailed studies that can allow the hydraulic engineering community to verify/reformulate old conceptions.

New tools are allowing for novel insights. Experiments were developed with particles constituted by different materials, with diverse porosity, moving in water/glycerol mixtures at several Reynolds numbers. Emadzadeh and Chiew present detailed observations of mean flow as well as turbulence statistics. They obtain useful conclusions regarding the impact of porosity and other variables on the flow separation, settling velocity, and turbulence statistics. In this way, they provide valuable information that has tremendous applications for the fields of sediment transport, sewage treatment, contaminant transport, adsorption of metals, etc.

This study was communicated at a time in which novel works attempt to uncover the multiple phenomena behind the simple notion of settling velocity. The work was unanimously praised by the two reviewers, who gave the paper the same grade, and by the associate editor, who agreed with the reviewers. In turn, the then–editor in chief stated that the paper reported “a well-thought-out study.”  

The Karl Emil Hilgard Hydraulic Prize is presented to the author or authors of the paper that is judged to be of superior merit in dealing with a problem of flowing water, either in theory or in practice.