Seeing in the dark: the fluid dynamics of sediment-rich flows


Most fluid flows are highly turbulent and contain two or more gas, fluid, or solid phases. Examples include geophysical (e.g. turbidity currents (see Figure 1), pyroclastic density currents, rivers) and industrial (e.g., food processing, water treatment and metallurgical slurries) flows. However, although they control the large-scale morphological development of the natural world, the dispersal of pollutants and the efficiency of industrial processes, monitoring such opaque, turbid, flows has been hindered by the inability of light nor sound to penetrate them. Full quantification of the processes driving particle motion- entrainment, transport and deposition- in multiphase fluid flows therefore remains the “holy grail” of process sedimentology.


This project aims to optimise the parameters of, and develop multifrequency inversion (e.g., see Rice et al., 2014; Azpiroz-Zabala et al., 2017; Simmons et al., 2020) and ultrasound imaging velocimetry (e.g., Dash et al., 2022) algorithms for, a tomographic (3D) ultrasound system, which for the first time will enable volumetric measurements of flow velocities, particle sizes and concentrations in sediment-laden, turbulent flows.

Figure 1. Streamwise velocity vectors of a near-transparent gravity current computed with Particle Tracking Velocimetry (red vectors = upstream directed, blue vectors = downstream directed) (video courtesy Marshall et al., 2023). Until now, it was not possible to collect these data in turbid, opaque, flows.


Experiments will be conducted on well-studied test cases (e.g. settling column, unidirectional flows in a pipe flow loop; Rice et al., 2014; Bux et al., 2019) to verify and validate the new instrument. We will then use it to quantify velocities, concentrations and bedform development within cohesive sediment-laden open-channel flows.

Expected Outcomes

The new instrument will help unpick the intricate relationships between fluid flow and sediment movement. It will also enable major improvements in understanding sediment transport processes and drive improvements in monitoring environmental and industrial flows. These advances have implications from river and coastal dynamics to palaeoenvironmental analysis.

Find out more

To watch a recent webinar with an introduction to the Panorama DTP and the research scholarships on offer at the University of Hull, click here. You can listen to a description of this project from lead supervisor Dr Rob Thomas at 5 minutes 12 seconds.


Azpiroz-Zabala, M., Cartigny, M.J.B., Talling, P.J., Parsons, D.R., Sumner, E.J., Clare, M.A., Simmons, S.M., Cooper, C., and Pope, E.L., 2017. Newly recognized turbidity current structure can explain prolonged flushing of submarine canyons. Science Advances 3(10), e1700200. DOI: 10.1126/sciadv.1700200

Bux, J., Peakall, J., Rice, H.P., Manga, M.S., Biggs, S., and Hunter, T.N., 2019. Measurement and density normalisation of acoustic attenuation and backscattering constants of arbitrary suspensions within the Rayleigh scattering regime. Applied Acoustics 146, 9-22. DOI: 10.1016/j.apacoust.2018.10.022

Dash, A., Hogendoorn, W., Oldenziel, G., and Poelma, C., 2022. Ultrasound imaging velocimetry in particle-laden flows: counteracting attenuation with correlation averaging. Experiments in Fluids 63, 56. DOI: 10.1007/s00348-022-03404-x

Marshall, C.R., Dorrell, R.M., Keevil, G.M., Peakall, J., and Tobias, S.M., 2023. On the role of transverse motion in pseudo-steady gravity currents. Exp Fluids 64, 63. DOI: 10.1007/s00348-023-03599-7

Rice, H.P., Fairweather, M., Hunter, T.N., Mahmoud, B., Biggs, S., and Peakall, J., 2014. Measuring particle concentration in multiphase pipe flow using acoustic backscatter: Generalization of the dual-frequency inversion method. Journal of the Acoustical Society of America 136, 156-169.

Simmons, S.M., Azpiroz-Zabala, M., Cartigny, M.J.B., Clare, M.A., Cooper, C., Parsons, D.R., Pope, E.L., Sumner, E.J., Talling, P.J., 2020. Novel Acoustic Method Provides First Detailed Measurements of Sediment Concentration Structure Within Submarine Turbidity Currents. Journal of Geophysical Research: Oceans 125(5), e2019JC015904. DOI: 10.1029/2019JC015904