The ability to influence macroscopic flow behaviour by manipulating
interfaces holds promise for significant impact in future engineering
technologies. For example, surface features of micron-size resolution
and hydrodynamic coatings are sought for turbulent drag reduction, in
much the same way as secretions of tono-filaments and lipid droplets
reduce drag on a dolphin skin; morphing surface textures are envisaged
for ``fly- by-feel'' technologies that mimic the ability of insects to
optimise lift; and use of electric fields is explored for manipulating
the interfacial behaviour of droplets in electro-sprays.
The key to achieving these challenging goals is to recognise that the
dependency between the micro- and the macro-scale is bi-lateral: while
the microscopic interface region can significantly alter the
macroscopic flow, the outer state co-equally affects the microscale
dynamics, thus establishing a feedback loop. A faithful representation
of the dynamics must therefore span 7-8 orders of magnitude in spatial
extent and 9-10 orders of magnitude in time. As a result, this level
of multi-scale modelling has remained beyond the most advanced
engineering simulation capabilities.
In this dCSE project we have developed the software infrastructure
for coupled continuum-molecular systems. The Molecular Dynamics (MD)
simulations track the motion of individual discrete atoms based on their mutual
interactions inside a confined domain. On the other hand, the continuum
software uses Direct Numerical Simulations (DNS) to solve the non-linear,
partial differential equations for the fluid velocity at all points within a
large computational domain.
Coupling between discrete and continuous simulations is a very active
research field, dating back to a seminal paper by O'Connell and Thompson
. There have been a number of key papers over
the last eighteen years, including, [2,3,4,5,6,7,8,9]. As
the number of researchers utilising coupled techniques continues to
grow, so does the need for an efficient, scalable and robust ways to
implement the coupled methodology.
To this end, the coupling of an MD algorithm ( ) and a DNS solver ( ) within a single, coupled framework has been achieved in the first phase of the dCSE proposal. This will form the basis of a multi- purpose computational coupling utility which will be made available to the HECToR community.
Lucian Anton 2012-05-31