Options for refractive index and viscosity matching to study variable density flows

Clément, Simon; Guillemain, Anaïs; McCleney, Amy; Bardet, Philippe M.

doi:10.1007/s00348-018-2496-1

Cited by 13 publications

(8 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To enable optical diagnostic deployment, two refractive index matched solutions of different densities are employed; their density difference is 3.00%. Additionally, the dynamic viscosity of the solutions are within 0.7% of each other at 20 • C. Details on the refractive index and dynamic viscosity matching, as well as on the linear stratification formation, are reported in [22].…”

Section: Experimental Methodsmentioning

confidence: 91%

PIV Data Clustering of a Buoyant Jet in a Stratified Environment

Serani

Durante

Diez

et al. 2019

AIAA Scitech 2019 Forum

View full text Add to dashboard Cite

Three spatial clustering approaches of a high-Reynolds number transient buoyant jet in a linearly stratified environment are applied along with proper orthogonal decomposition to identify similar/consistent regions in the domain of interest. The velocity fields analyzed are obtained from an experimental test with large scale, time-resolved, particle image velocimetry (PIV) measurements. Clustering is performed by the k-means method considering: (a) crosssection velocity profiles, (b) point-wise energy spectra, and (c) point-wise Reynolds stress tensor components. Three metrics are used for the assessment of clustering approaches, namely: (a) within-cluster sum of squares, (b) average silhouette, and (c) within-cluster number of POD modes required to resolve prescribed levels of total variance/energy. Results are promising and lay the foundation for an in depth analysis of local features of complex flows as well as the formulation of efficient reduced order models.

show abstract

Section: Experimental Methodsmentioning

confidence: 91%

PIV Data Clustering of a Buoyant Jet in a Stratified Environment

Serani

Durante

Diez

et al. 2019

AIAA Scitech 2019 Forum

View full text Add to dashboard Cite

show abstract

“…stratification but also to allow the fluid to be optically homogeneous. Considerations for choosing combinations of solutes have been explored in detail, including the potential for double diffusion, linearity in the refractive index and density, effects on viscosity and cost (McDougall 1979;Barrett & Van Atta 1991;Daviero, Roberts & Maile 2001;Clément et al 2018). Furthermore, in experiments with PLIF, the choice of the solutes also needs to reflect the Schmidt numbers of the fluorescent dye and the stratifying agent (Troy & Koseff 2005).…”

Section: Discussionmentioning

confidence: 99%

On the interaction between oncoming internal waves and a dense gravity current in a two-layer stratification

2021

View full text Add to dashboard Cite

A series of laboratory experiments was conducted to investigate the dynamics of a dense gravity current flowing down an inclined slope into a two-layer stratification in the presence of oncoming internal interfacial waves. The experiment is set up such that the gravity current propagates towards a wave maker emitting interfacial waves such that the current and waves propagate in opposite directions. The results were compared with the case of gravity current without oncoming waves. The gravity current splits into a portion that inserts itself into the pycnocline as an interflow and another that propagates down the slope as an underflow, with the proportionality depending on the characteristics of the gravity current and the oncoming waves when they are present. The interflow is shown to arise from a combination of detrainment and the preferential insertion of fluid with density greater than the upper layer and less than lower layer along the pycnocline. The mass flux of the interflow is observed to be reduced by the oncoming waves, as waves act to decrease the interflow velocity. The internal waves also increase the path length that the interflow must travel. A combination of reduced velocities and increased path length explains the observed reduction in cumulative flux. The trend of the final cumulative flux is consistent with the mass change observed by comparing density profiles obtained before and after the experiment.

show abstract

“…This technique is possible in a laboratory environment if the fluid temperature is stable (as its refractive index retains a known value). This is called refractive index matching (RIM) and has been used not only to study granular flows but also other fluids (Budwig 1994;Li et al 2005;Wiederseiner et al 2011;Dijksman et al 2012;Bai and Katz 2014;Clément et al 2018;Rousseau and Ancey 2020).…”

Section: Refractive Index Matchingmentioning

confidence: 99%

“…This was rejected due to the fluid's high viscosity ( = 270 cP) and the low density difference between the particles and the fluid, ρ = (𝜚 * − 𝜚 f * )∕𝜚 f * = 0.102 . The second was a combination of an aqueous sodium iodide solution (for studies using this combination, see Narrow et al 2000;Bai and Katz 2014;Clément et al 2018) and borosilicate glass beads, but the interstitial fluid was too dense and the beads showed positive buoyancy. Finally, we retained borosilicate glass for the particles and a mixture of ethanol and benzyl alcohol for the interstitial fluid-a combination recently used by van der Vaart et al (2015) and Rousseau and Ancey (2020).…”

Section: Refractive Index Matchingmentioning

confidence: 99%

A conveyor belt experimental setup to study the internal dynamics of granular avalanches

Trewhela

Ancey

2021

Exp Fluids

View full text Add to dashboard Cite

This paper shows how a conveyor belt setup can be used to study the dynamics of stationary granular flows. To visualise the flow within the granular bulk and, in particular, determine its composition and the velocity field, we used the refractive index matching (RIM) technique combined with particle tracking velocimetry and coarse-graining algorithms. Implementing RIM posed varied technical, design and construction difficulties. To test the experimental setup and go beyond a mere proof of concept, we carried out granular flow experiments involving monodisperse and bidisperse borosilicate glass beads. These flows resulted in stationary avalanches with distinct regions whose structures were classified as: (i) a convective-bulged front, (ii) a compact-layered tail and, between them, (iii) a breaking size-segregation wave structure. We found that the bulk strain rate, represented by its tensor invariants, varied significantly between the identified flow structures, and their values supported the observed avalanche characteristics. The flow velocity fields’ interpolated profiles adjusted well to a Bagnold-like profile, although a considerable basal velocity slip was measured. We calculated a segregation flux using recent developments in particle-size segregation theory. Along with vertical velocity changes and high expansion rates, segregation fluxes were markedly higher at the avalanche’s leading edge, suggesting a connection between flow rheology and grain segregation. The experimental conveyor belt’s results showed the potential for further theoretical developments in rheology and segregation-coupled models. Graphic Abstract

show abstract

Options for refractive index and viscosity matching to study variable density flows

Cited by 13 publications

References 22 publications

PIV Data Clustering of a Buoyant Jet in a Stratified Environment

PIV Data Clustering of a Buoyant Jet in a Stratified Environment

On the interaction between oncoming internal waves and a dense gravity current in a two-layer stratification

A conveyor belt experimental setup to study the internal dynamics of granular avalanches

Contact Info

Product

Resources

About