title: Thermal diffusion by Brownian-motion-induced fluid stress.
abstract: 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 emerging. Here we investigate the dynamics of DNA and spherical particles subjected to a thermal gradient using a combination of Brownian dynamics and the lattice Boltzmann method. We observe that the DNA molecules will migrate to colder regions of the channel, an observation also made in experiments. In fact, the thermal diffusion coefficient found agrees quantitatively with the experimentally measured value. We also observe that the thermal diffusion coefficient decreases as the radius of the studied spherical particles increases. Furthermore, we observe that the thermal-fluctuation-fluid-momentum-flux coupling induces a gradient in the stress which leads to thermal migration in both systems.
authors.affiliation: Institute of Physics, Academia Sinica, Taipei, Taiwan.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Kreft
authors.forename: Yeng-Long
authors.initials: YL
authors.lastname: Chen
mesh_terms: D000818:Animals; D001703:Biophysics / Q000379:methods*; D004247:DNA / Q000032:analysis; D004058:Diffusion; D004463:Ecology / Q000379:methods; D004641:Emigration and Immigration; D006358:Hot Temperature; D008962:Models, Theoretical; D011157:Population Dynamics; D055672:Static Electricity; D013696:Temperature; D013816:Thermodynamics
chemical_list: D004247:DNA