Details of Award
NERC Reference : NE/C514823/1
Turbulence modulation in high concentration suspension flows: implications for natural gravity currents.
Grant Award
- Principal Investigator:
- Professor JL Best, University of Leeds, School of Earth and Environment
- Co-Investigator:
- Professor W McCaffrey, University of Leeds, School of Earth and Environment
- Grant held at:
- University of Leeds, School of Earth and Environment
- Science Area:
- Marine
- Freshwater
- Earth
- Overall Classification:
- Earth
- ENRIs:
- Natural Resource Management
- Environmental Risks and Hazards
- Science Topics:
- Earth Resources
- Volcanic Processes
- Sediment/Sedimentary Processes
- Geohazards
- Abstract:
- Sediment is carried in many types of natural flow, often at very low concentrations. Examples of this might include the majority of streams and rivers, dust storms, and tidal currents. In other flows, however, sediment can be carried in very high concentrations, and the flows may be dangerous, because they are of high energy and move very rapidly. Examples of these type of flows would include some rivers in flood, some types of flows from volcanoes (pyroclastic flows), snow avalanches and turbidity currents in lakes and the deep sea. In fact the last three types of flow, pyroclastic flows, snow avalanches and turbidity currents are very similar - they are 'particulate gravity currents' which are a fluid-like mixture of a carrier fluid (such as hot volcanic gas, air or water) and sediment, which move due to the effect of gravity on the sediment particles 'suspended' within the flows. Particles within rivers and particulate gravity currents may be suspended by many different mechanisms. We are mostly interested in two of these: fluid turbulence and particle-particle interactions. In turbulent flows, although the average direction of movement is downstream, rapid, random movements are superimposed on top of this average velocity. These turbulent movements are responsible for entraining sediment particles into the flow, and for keeping them there. As more sediment is transported (i.e. as the particle concentration increases), grains may collide against one another, and rebound apart. This also helps to keep them in suspension. At the moment, we do not really understand how the turbulence structure of the flows (that is, the energy used in turbulence, the distance over which the turbulent motions occur, and their speed) changes as particle concentration increases. It is, however, very important for us to understand this, as it is possible that these flows could become either more or less turbulent as concentration increases, and therefore become either more of less 'efficient' at carrying the sediment. If flows are more 'efficient' at carrying sediment, they may travel further and faster. If the are less 'efficient', they may slow down more quickly, deposit their sediment and eventually stop. So by understanding the effect of changes in sediment concentration, we hope to make better predictions of how these flows will behave. We can either do this directly, or by using the new information to make better computer models that predict flow behaviour. There are many applications of being able to predict flow behaviour. For example, if we can better predict the distances that avalanches and pyroclastic flows can travel over, we can thus make better more accurate predictions of where danger areas are. Also, oceanic turbidity currents commonly deposit sediments that, much later over millions of years, become oil or gas reservoirs, and so being able to predict accurately where these sediments are may help us better explore for, and manage, hydrocarbon reserves.
- NERC Reference:
- NE/C514823/1
- Grant Stage:
- Completed
- Scheme:
- Small Grants Pre FEC
- Grant Status:
- Closed
- Programme:
- Small Grants
This grant award has a total value of £30,447
FDAB - Financial Details (Award breakdown by headings)
| Total - Staff | Total - T&S | Total - Other Costs | Total - Indirect Costs |
|---|---|---|---|
| £2,462 | £1,031 | £25,823 | £1,132 |
If you need further help, please read the user guide.