Slurry Transport, a Study in Continuity, Fully Stratified Flow
Type:
Presented during:
WODCON XXII - Enhance the Harmony between Dredging and Ecology
Authors:
S.A. Miedema
Abstract
"In the past years a new slurry transport model has been developed, based on an extensive literature survey, 5 different flow regimes and a constant spatial volumetric concentration (in time and space). This model is named the Delft Head Loss&Limit Deposit Velocity Framework or DHLLDV. Since the previous WODCON in 2016 in Miami, DHLLDV has been modified and extended. The paper will describe the most important addition to DHLLDV. The most important addition is the criterion determining which of two models should be used, the heterogeneous flow regime model or the sliding flow regime model. The large particle model results in fully stratified flow for which Wilson determined a simple criterion, the particle diameter should be larger than 0.015 times the pipe diameter. Evidence for this criterion could not be found. Based on an old Bagnold criterion for the occurrence of suspension, a new criterion for fully stratified flow has been derived. Fully stratified flow is also named Sliding Flow in the DHLLDV Framework. Experimental data validating the transition between the two models is shown, also showing data for the heterogeneous flow regime and the homogeneous flow regime. The data matches the new development very well and proves the Wilson criterion is correct, but now with a physical basis. It is remarkable that this criterion does not seem to depend on the particle density or submerged density and hardly on the line speed."
Keywords: Slurry transport, Fully stratified flow, Concentration distribution, Sliding flow.