(73c) &Lambda DNA Thermal Migration in a Microchannel

The Ludwig-Soret effect, the migration of a species due to a temperature gradient, has been extensively studied without a complete picture of its cause. Many particle and polymer solutions have been used to study the phenomena; here we investigate the dynamics of DNA confined to a microchannel and subjected to a thermal gradient using a combination of Brownian dyanmics and the lattice Boltzmann method. We observe that the DNA molecules will migrate to colder regions of the channel, an observation also made in the experiments of Duhr, et al. In fact, the thermal diffusion coefficient found for a range of temperature gradients agrees nearly quantitatively with the experimental value. Furthermore, we use the simulation to understand how the interaction of the DNA with the solvent leads to thermal migration via the thermal fluctuations-fluid momentum flux coupling.