Comparing the transitional behaviour of kaolinite and bentonite suspension flows

Abstract

Past research has demonstrated the dramatic effects that variations in suspended clay can have on the properties of flow by producing a range of transitional flows between turbulent and laminar states, depending on clay concentration and fluid shear. Past studies have been restricted to kaolinite flows, a clay mineral that has relatively weak cohesive properties. This paper extends these studies to suspension flows of bentonite, a clay mineral that attains higher viscosities at far lower volumetric concentrations within a flow. The results show that the types of transitional flow behaviour recognized in past studies can also be found in bentonite suspension flows, but at lower suspended sediment concentrations, thus demonstrating an even more dramatic effect on flow properties, and potentially on sediment transport and resulting bed morphology, than kaolinite flows. The paper proposes new stability diagrams for the phase space of bentonite flows and compares these to past work on kaolinite suspension flows. These new data suggest that the transitional-flow Reynolds number can be used to delineate the types of transitional flow across different clay types and assess modern and ancient clay-suspension flows.

Response of unconfined turbidity current to deep‐water fold and thrust belt topography: Orthogonal incidence on solitary and segmented folds

“…18E) invoked as key supporting evidence (Pickering & Hiscott, 1985;Haughton, 1994Haughton, , 2000Kneller & McCaffrey, 1999;McCaffrey & Kneller, 2001;Grecula et al, 2003;Salles et al, 2014;Patacci et al, 2015;Marini et al, 2016;Tinterri et al, 2016). However, this concept may require some caution, because flow reversals can occur without containment, while thick mud caps may reflect either en masse deposition from a trailing flow of fluidal mud or hemipelagic fallout between consecutive turbidity currents Baas et al, 2009Baas et al, , 2016Leszczy nski et al, 2015). As shown by Ge et al (2017) and the present study, a reverse underflow can be generated on a counter-slope of a few degrees under the load of a decelerated and critically thickened parental current.…”

Flow dynamics at the origin of thin clayey sand lacustrine turbidites: Examples from Lake Hazar, Turkey

“…There are some rare recent studies such as Baas et al . () who compared the behaviour of bentonite to kaolinite in a new set of experiments on suspended flows. This type of investigation should be multiplied and expanded to improve current understanding of the behaviour of clay‐rich turbidity currents in real settings.…”

“…Interaction between water chemistry and clay type has not been investigated in detail for fast-moving turbidity currents where turbulence and sedimentwater mixing are suspected to have a great impact. There are some rare recent studies such as Baas et al (2016) who compared the behaviour of bentonite to kaolinite in a new set of experiments on suspended flows. This type of investigation should be multiplied and expanded to improve current understanding of the behaviour of clay-rich turbidity currents in real settings.…”

An integrated process‐based model of flutes and tool marks in deep‐water environments: Implications for palaeohydraulics, the Bouma sequence and hybrid event beds

“…Recent years have witnessed a step‐change in our understanding of flows that are transitional in their behaviour between turbulent and laminar states, due to the addition of mud in suspension (Wang & Plate, ; Baas & Best, , , ; Baas et al., , , ,b). As an increasing quantity of clay is added to a flow, the particles begin to form flocs and longer chains because of electrostatic bonding, and eventually gel, which may significantly influence the rheology of the flow.…”

“…Despite this complexity, experimental studies (Baas & Best, ; Baas et al., , ,b) have shown that, as clays are added to a flow through direct substrate entrainment or abrasion of muddy clasts, a series of predictable and consistent changes occur that modify the mean velocity profile and turbulence structure of the flow (Fig. ).…”