PhD projectExploiting wavy relief formation in fluidised suspensions to measure constitutive properties

Supervisor: Dr A. Juel (anne.juel@manchester.ac.uk)

For more information: http://www.ma.man.ac.uk/~ajuel

Whereas models describing fluid flows are well-established, albeit difficult to solve, granular flows lack a continuum description. This project proposes to exploit the analogy between a granular and a fluid instability to measure constitutive properties of the dense granular suspension.

When a layer of heavy grains immersed in water is oscillated rapidly in the horizontal direction, the layer of grains fluidizes into a wavy relief above a critical value of the forcing. This “interfacial” instability has a close fluid analog that we have researched extensively1,2 and is a very robust phenomenon. In the first part of the project, we propose to characterise the onset of this fluidization instability and the evolution of the granular layer prior to fluidization by analogy with the fluid system. Preliminary results suggest that the wavelengths of the reliefs follow similar variations with the excitation parameter. However, the wavelength varies with grain type, and in a second part, our study will aim to extract detailed information about the friction properties of the suspensions by investigating the instability onset in a range of grains immersed in fluids of different viscosities. Another important property of grains is their roughness, and the sensitivity of the onset parameter to grain roughness will be assessed as there is cuurently no reliable method of measuring particle roughness effects in suspensions. The project is primarily experimental but will involve collaborations with modellers.

1 Jalikop, S.V. & Juel A (2008) Capillary-gravity waves in oscillating two-layer flows. Submitted to J. Fluid Mech.

2 Talib,E., Jalikop, S.V. & Juel A (2007) The influence of viscosity on the onset of the frozen wave: theory and experiment. J. Fluid Mech. 584, 45-68.