The influence of relative fluid depth on initial bedform dynamics in closed, horizontal pipe flow

Abstract

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Highlights  Particle bed depth in horizontal pipe flow measured with acoustic backscatter.  Evolution of bedforms over time observed and categorized into five types.  Bedform type influenced by initial flow rate, relative fluid depth.  Observed bedform evolution supports distinct ripple and dune modes.  Universal scalings for pipe, channel and environmental flows proposed.

Extending estimation of the critical deposition velocity in solid–liquid pipe flow to ideal and non-ideal particles at low and intermediate solid volume fractions

“…The plastic species are, however, rough and non-spherical as described in Sec. 3.3 and (Rice et al, 2017) and m/ Farr is lower in those cases. The ratio m/ Farr is lower still for barium sulphate: its broad size distribution (as characterised by a high value of S) would yield a high packing fraction if the particles were ideal hard spheres.…”

“…and Mastersizer 3000 laser diffraction sizers and the densities with a Micromeritics AccuPyc 1300 pycnometer. In addition, the Corey shape factor, Fs (Corey, 1949;Dietrich, 1982) and Powers roundness factor, P (Powers, 1953;Syvitski, 2007) have been measured previously for the large plastic species (Rice et al, 2017) with a Retsch Camsizer XT optical sizing instrument and were found to be Fs = 0.842 (where 0 corresponds to a rod and 1 to a sphere) and P = 2.49 (i.e., sub-angular, where 0 corresponds to very angular and 6 to well rounded). b Updated using data at higher or corrected following review of Rice et al (2015).…”

“…Solid-liquid slurry flows can be categorized into fully suspended and homogeneous (or pseudohomogeneous); heterogeneous, in which a solids concentration gradient exists; flow with moving bed (or saltation flow or two-layer flow flow with a stationary bed sometimes three-layer flow) (Peysson et al, 2009;Rice et al, 2017); and plug flow, in which the solid span the conduit and move en masse (Crowe, 2006;Doron and Barnea, 1995;Wasp et al, 1977). Each of these flow regimes, which are illustrated in idealised form elsewhere (Doron and Barnea, 1996;Rice et al, 2015), can be distinguished by a critical velocity or flow rate, which are essential flow parameters for operators working with high-value or hazardous substances in the food, nuclear and minerals processing industries, for example (Bux et al, 2017;Poloski et al, 2010;Thomas, 1961Thomas, , 1962 because of the associated pumping and energy requirements, the possibility of blockages and, in the case of stationary deposits of chemically or radiologically active materials, the increased risk of corrosion, heat deposition and elevated radiation dose to operators.…”

Particle behavior in a turbulent pipe flow with a flat bed

“…A linear variation between nodes is assumed, so that the value of variables at the cell faces are averages of the values at the appropriate adjacent nodes, leading to space discretisation corresponding to a central difference scheme. Fourth-order pressure smoothing based on the method of Rhie and Chow (1983) is used to prevent oscillations in the pressure field. Time advancement uses an implicit Gear method for all transport terms, with the procedure second-order accurate in space and time.…”

“…two-way coupling between the fluid flow and the particles, such that the fluid influences the particles and the particles influence the fluid, and collisions between particles) between the particles and the fluid flow will occur, with associated particle agglomeration. Additionally, bedforms in pipe flows can be categorised into five types (Rice et al, 2017): plane flat beds that do not vary with time; bedforms of regular period (time independent); time-dependent bedforms of increasing period; time dependent bedforms with unstable/cyclic period; and beds with no particle motion on the surface of the bed. Particle deposition, bed formation and evolution are therefore complex processes the prediction of which would entail high computational costs, particularly since the use of boundary resolving approaches for the particles would be required.…”