Simplified Physically Based Model for Estimating Effective Floc Density

• Published in: Journal of hydraulic engineering (New York, N.Y.) Vol. 137; no. 8; pp. 843 - 846
• Main Authors: Nguyen, Hoang-Ha, Chua, Lloyd H. C
• Format: Journal Article
• Language: English
• Published: Reston, VA American Society of Civil Engineers 01.08.2011
• Subjects: Applied sciences; Buildings. Public works; Calibration; Computation methods. Tables. Charts; Density; Dimensional analysis; Empirical analysis; Estimating; Exact sciences and technology; Hydraulic constructions; Hydraulic engineering; Mathematical analysis; Mathematical models; Structural analysis. Stresses; TECHNICAL NOTES; Particle size; Sediment; Hydraulics; Fractals; Sediments; Density; Modeling; Velocity; Particles; Settling velocity; Fractal dimension; Dimensional analysis; Flocculation; Cohesive sediment; Decantation
• ISSN: 0733-9429; 1943-7900
• DOI: 10.1061/(ASCE)HY.1943-7900.0000355

This paper applies dimensional analysis to propose an alternative model for estimating the effective density of flocs (Δρf). The model takes into account the effective density of the primary particles, in addition to the sizes of the floc and primary particles, and does not consider the concept of self-similarity. The model contains three dimensionless products and two empirical parameters (αf and βf), which were calibrated by using data available in the literature. Values of αf=0.7 and βf=0.8 were obtained. The average value of the primary particle size (Dp) for the data used in the analysis, inferred from the new model, was found to vary from 0.05 μm to 100 μm with a mean value of 2.5 μm. Good comparisons were obtained in comparing the estimated floc-settling velocity on the basis of the proposed model for effective floc density with the measured value.