Particles bed morphology under an oscillating stiff and flexible plates

Anna Prati,Luigi La Ragione,James T Jenkins,Michele Larcher,M.A Aguirre,L.A Pugnaloni,R Soto,S Luding

doi:10.1051/epjconf/202124909003

Anna Prati, Luigi La Ragione + Show 6 more

Open Access

https://doi.org/10.1051/epjconf/202124909003

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Abstract

We analyse the different morphologies induced by an oscillating plate above an erodible bed. We present some data describing how the shape and the stiffness of the plate affects the main features of the generated heap. We investigate several configurations with different geometries, frequencies and the amplitudes. Some preliminary results are available, in which the role of the flexibility of the plate is taken in account. Unlike the rigid plate in which a proper oscillation induces the formation of one heap, the morphology of the bed is now characterized by more than one heap due to a different pressure profile induced by a flexible plate.

Highlights

La Ragione et al [1] have brought attention to a mechanism of failure for a fluid-saturated bed in an oscillated flow. They show that an oscillating plate in the water above a fluid-saturated particle bed induces pressure gradients that provoke particle motion and a formation of a heap
We focus on the role of the stiffness of the plate and how this affects the morphology of the bed after failure occurs
As the plate oscillates with a given frequency f and amplitude A, a vertical pore pressure gradient is induced in the bed, so when it is larger than the buoyant specific weight of the particles, a vertical motion occurs

Summary

Introduction

La Ragione et al [1] have brought attention to a mechanism of failure for a fluid-saturated bed in an oscillated flow. Data for the present work have been collected using two different laser sheets, high speed cameras and a hydrophone to measure the pressure above the bed. As the plate oscillates with a given frequency f and amplitude A, a vertical pore pressure gradient is induced in the bed, so when it is larger than the buoyant specific weight of the particles, a vertical motion occurs. This motion is different when the plate moves upwards or downwards, creating an irreversible feature in the bed, with a formation of a heap, that is evidence. All the plates used for this work are pictured in

The flexion data

The heap profiles

The pressure data