Construction of drag coefficient models of flake particles with different sectional shapes

The driving force for the settling motion of particles is the difference between the trailing force of the fluid and the effective force of gravity. The drag coefficient is an important parameter for predicting the drag force on an object in a fluid. Although the drag coefficients of spherical and regular non-spherical particles have been studied more, there are fewer studies on flake particles with different cross-sectional shapes. In this study, we analyzed the effects of thickness-to-diameter ratio and circularity on settling velocity by using a self-designed monitoring system, constructed a new model Z=0.7815λ2+0.0176c2+0.1 for describing the shape of flake particles, and obtained a new drag coefficient model Cd=0.0451Z−2.6438Re(−0.9236Z0.1102+1)+A containing Z and the Reynolds number Re, with an average relative error of 8.97%. Based on this model, the settling end velocity of flake particles with different cross-sectional shapes was predicted using MATLAB, with an average relative error of 5.52%, which is a good prediction. This study provides a theoretical basis for the settling behavior of flake particles.