Paul Jarvis

Career

  • 2008-2012: BA, MSci Natural Sciences, University of Cambridge
  • 2012-2016: Ph.D Geology, University of Bristol
  • 2016-present: Postdoctoral research assistant, University of Cambridge 

Research

Currently working in Dr Nathalie Vriend's granular flow group at DAMTP, I am interested in fluid dynamical problems with applications to geological and geophysical flows. The main focus of my present research is the formation and continued development of sand ripples and dunes. 

Sedimentary bedforms form in environments where a fluid flows over an erodible deposit. Natural examples can be subaerial (desert dunes, snow drifts, remombilised volcanic ash deposits) or subaqueous (river ripples, coastal dunes) and display a vast array of different structures and geometries (transverse ripples, barchan dunes, star dunes, sand bars). Such structures are also important industrially, such as during the transport of multiphase flows.

My current project is an experimental investigation into the formation and evolution of transverse ripples and dunes within an annular flume. The flume contains a sediment bed (either sand or ballotini) overlain by water, and is sat on a rotating table. Submerged in the water are a series of fixed paddles. As the flume rotates past the paddles, a shear flow is created in the fluid. This exerts a shear stress on the sediment bed, destabilising the  surface, leading to the formation of ripples. As these ripples grow, they interact and coalesce to form larger dunes. 

We are attempting to quantify the temporal evolution of the sediment surface. In particular we are interested in the wavelength of the initial disturbances, a quantity for which opposing theoretical predictions exist in the literature. We are also interested in the dynamics of the interaction between a pair of ripples/dunes, and are attempting to quantitatively determine the conditions for which coalescence will occur.