Settling Characteristics of Calcareous Sand

This paper provides quantitative comparisons and relationships for the fall velocities and drag coefficients of 998 calcareous sand grains collected on Oahu, Hawaii. Laboratory analyses of the grains provide the three orthogonal dimensions, fall velocity, and density, from which the nominal diameter, drag coefficient, Reynolds number, and shape factor are evaluated for each grain. The fall velocity and drag coefficient expressed, respectively, as functions of nominal diameter and Reynolds number show strong correlation over a wide range of Corey shape factors. The present relationships are validated with published data based on quartz grains. Analysis of the data by flow regime shows that particle shape has a stronger influence on the settling characteristics when turbulent boundary layers develop around the grains.