Anisotropy occurs throughout the physical world and is perhaps most commonly encountered in material science, where a material's physical properties may depend on specific directions. For instance, the absorbance, conductivity, strength, etc. are often different along different directions in a substance.
These properties can be manufactured to be anisotropic, as in the case of liquid crystal materials which are used in visual display applications where, due to their anisotropic interaction with light, it is possible to alter the transmittance of light through a display device.
Anisotropy also often occurs in nature in a number of ways. For instance seismic anisotropy is the variation of wavespeed with direction due to the long range order of small scale features such as crystals, cracks and pores. The alignment of these features can create a directional dependence of the elastic properties of rock which is then observed through the anisotropy of seismic wave propagation and other extremely important properties (i.e. strength, crack propagation, porosity, electrical anisotropy, and electrical conductivity). This type of anisotropy can occur when the natural formation processes occur in an anisotropic way (i.e. through layering in sedimentary material or through extensional flows which solidify).
Such geological anisotropic properties then influence secondary phenomena such as the flow of fluids within porous rocks. Indeed the hydraulic conductivity of aquifers is often anisotropic for this reason. The presence of anisotropy in a system therefore has important consequences for the human interaction with such systems. For instance the anisotropy of crack propagation is crucial when analysing failure risks and directional factors must be considered when investigating the risks of pollution when the pollutant is spreading through anisotropic permeable rock.
Geology is not the only area of the natural world where anisotropy occurs: other examples include “active fluid” systems. In such systems there are active organisms which are influenced by the flow of fluid around them but, crucially, also influence the flow. When the organisms are anisotropic (as is often the case) a model of such a system must include these inherent asymmetries. Models of bacteria and even larger organisms such as fish have started to be developed over the last few years in order to examine the order, self‐organisation and pattern formation within these systems.
This project aims to use methods from material science, fluid dynamics and the mathematical modelling of anisotropy to investigate anisotropy in the natural environment.
Funding
The initial stage of this project consists of a one-year sabbatical period for Prof. Nigel Mottram, funded through a "Discipline Hopping" grant, by the Medical Research Council (supported by EPSRC, BBSRC and NERC).
This first phase will involve investigations into various instances of anisotropy in the natural environment (see pages on this web-site), including collaborations with members of theScottish Association of Marine Science at the Scottish Marine Institute in Dunstaffnage, near Oban.
Associated funding has also been provided by the University Strathclyde, through a "Bridging the Gap" project, and the Carnegie Trust for the Universities of Scotland.
