Modelling ripple morphodynamics driven by colloidal deposition

Abstract

Fluid dynamics between a particle-laden flow and an evolving boundary are found in various contexts. We numerically simulated the morphodynamics of silica particle deposition from flowing water within geothermal heat exchangers using the arbitrary LagrangianEulerian method. The silica particles were of colloidal size, with submicron diameters, which were primarily transported through the water via Brownian motion. First, we validated the Euler-Euler approach for modelling the transport and deposition of these colloidal particles within a fluid by comparing our simulation results with existing experiments of colloidal polystyrene deposition. Then we combined this multiphase model with a dynamic mesh model to track the gradually accumulated silica along the pipe walls of a heat exchanger. Surface roughness was modelled by prescribing sinusoidally-shaped protrusions on the wall boundary. The silica bed height grew quickest at the peaks of the ripples and the spacing between the protrusions remained relatively constant. The rough surface experienced a 20 % reduction in silica deposition when compared to a smooth surface. We also discuss the challenges of mesh deforming simulations with an emphasis on the mesh quality as the geometry changes over time.

Theoretical and experimental perspectives in utilizing nanobubbles as inhibitors of corrosion and scale in geothermal power plant

“…The rate of nucleation of the calcium carbonate scale increases by an increase in surface roughness [148]. Additionally, geothermal fluid is known to precipitate scale when subjected to high shear stress [149]. The shear stress is linked to the slip length on the nanometer scale.…”

Viscous transport in eroding porous media

“…Flow in porous media is further complicated when boundaries evolve dynamically in response to the fluid flow. This coupling between geometry and flow occurs, for example, in applications involving melting (Beckermann & Viskanta 1988;Rycroft & Bazant 2016;Jambon-Puillet, Shahidzadeh & Bonn 2018;Favier, Purseed & Duchemin 2019;Morrow et al 2019), dissolution (Kang et al 2002;Huang, Moore & Ristroph 2015;Moore 2017;Wykes, Huang & Ristroph 2018), deposition (Johnson & Elimelech 1995;Hewett & Sellier 2018), biofilm growth (Tang, Valocchi & Werth 2015) and crack formation (Cho et al 2019). We focus on erosion, a fluid-mechanical process that is prevalent in many geophysical, hydrological and industrial applications (Berhanu et al 2012;Ristroph et al 2012;Hewett & Sellier 2017;Lachaussée et al 2018;López, Stickland & Dempster 2018;Allen 2019;Amin et al 2019).…”

“…Flow in porous media is further complicated when boundaries evolve dynamically in response to the fluid flow. This coupling between geometry and flow occurs, for example, in applications involving melting (Beckermann & Viskanta 1988;Rycroft & Bazant 2016;Jambon-Puillet et al 2018;Favier et al 2019;Morrow et al 2019), dissolution (Kang et al 2002;Huang et al 2015;Moore 2017;Wykes et al 2018), deposition (Johnson & Elimelech 1995;Hewett & Sellier 2018), biofilm growth (Tang et al 2015), and crack Figure 1: 50 bodies eroding in a Hagen-Poiseuille flow. The six snapshots are equispaced in time, and the color is the magnitude of the fluid velocity in a logarithmic scale.…”