| EPSRC Reference: |
EP/P000029/1 |
| Title: |
Experimental study of atmospheric stratification in environmental flows (StratEnFlo) |
| Principal Investigator: |
Carpentieri, Dr M |
| Other Investigators: |
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| Project Partners: |
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| Department: |
Mechanical Engineering Sciences |
| Organisation: |
University of Surrey |
| Scheme: |
First Grant - Revised 2009 |
| Starts: |
01 November 2016 |
Ends: |
31 October 2018 |
Value (£): |
94,631
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| EPSRC Research Topic Classifications: |
| Aerodynamics |
Urban & Land Management |
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Summary on Grant Application Form |
Poor urban air quality and the threat of terrorist attacks by spreading hazardous substances in cities are a real concern for everyone. In order to prevent health hazards and to plan emergency procedures effectively, we need to be able to predict and simulate how gases and particles spread. A number of mathematical models currently exist that are able to simulate flow and dispersion with reasonable speed and accuracy at the required small scales, however there are still huge gaps in our knowledge and these models do not work well in all conditions. One of the main problems that current models display is in the way they treat atmospheric stratification. The proposed research will tackle this problem and will establish the role of thermal stratification in flow and dispersion in urban areas.
Stratification is common in environmental flows. This is due, for example, to variations in temperature and humidity with height in the atmosphere, or to variations in temperatures and salinity in the oceans. Neutral atmospheric stratification is characterised by an adiabatic profile of potential temperature, meaning that vertical motions of fluid particles are neither amplified nor damped. On the other hand, vertical movements are enhanced in unstable stratification, while stable flows are characterised by attenuated vertical motion.
Although stratification plays a very important role in atmospheric flow and dispersion, the vast majority of studies focus only on neutral flows, mainly because they are simpler to treat either experimentally or numerically. The proposed research aims to start bridging this gap using one of the very few facilities in Europe, or for that matter the world, that is capable of simulating non-neutral atmospheric boundary layer flows.
In meteorology and in mesoscale air quality models, stratification is an important feature, with parametrisations that are usually accurate enough to capture the main behaviour of the flow in different conditions of stability. At smaller scales, however, these relatively simple parametrisations are inadequate. While other small scale features, such as local geometry, may also become more important in determining flow conditions at such scales, stratification plays a significant role.
The prevalence of non-neutral atmospheric stratification (either stable or unstable) is well known, and a number of studies have highlighted the important effects this has on flow and dispersion. Systematic laboratory studies, however, are very rare, due to the complexity of the physical system to be studied and the very few facilities in the world capable of simulating a deep, non-neutral boundary layer. Because of this lack of experimental data-sets, most current mathematical parametrisations that account for this very important effect were developed using data from neutral test cases, sparse and rather uncertain field measurements, and some theoretical reasoning. The capabilities of the EnFlo laboratory offer a unique opportunity to bridge this gap in current models.
The main purpose of the proposed research is to establish the role of thermal stratification, both external and local, on flow and dispersion within an array of building-like obstacles. Experimental methodologies to simulate these issues will also be refined and further developed, as no established procedures and strategies currently exist. The principal outcome of the work will be a better understanding of the physics of this kind of atmospheric flow, focussing mainly in flow and pollutant dispersion within the urban canopy (particularly below roof level). A systematic experimental database on flow and dispersion in non-neutral flows will be produced. The data-set will help develop parametrisations and mathematical models able to predict atmospheric flow and dispersion at small scales more reliably, for example in urban areas or in wind farms.
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Key Findings |
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This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk
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Potential use in non-academic contexts |
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This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk
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Impacts |
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| Description |
This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk |
| Summary |
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| Date Materialised |
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Sectors submitted by the Researcher |
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This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk
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| Project URL: |
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| Further Information: |
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| Organisation Website: |
http://www.surrey.ac.uk |