Multiscale simulation of dilute DNA in a roll-knife coating flow

Abstract

SynopsisThe dynamics of dilute solutions of DNA flowing in a scaled down roll-knife coating flow are investigated on multiple scales. The flow is generated between a rotating roll and a stationary glass knife, and extension of fluorescently stained DNA molecules is measured at the minimum gap at low roll speeds. The macroscopic flow is computed by solving the continuum equations of motion with the finite element method; the microscale behavior of DNA molecules is predicted by Brownian dynamics combined with successive fine-graining. The simulations predict that the DNA should stretch almost to full extension near the roll surface in the region of minimum gap; this does not agree with experimental measurements. The assumption that the flow is nearly homogeneous on the length scale of the polymer molecules, commonly used in processing flows as well as Brownian dynamics simulations of simple flows, fails near free surfaces, and is the likely cause of the discrepancy. Evidence from the literature suggests that similar nonlocal effects may be present in coating and ink-jet printing flows of high molecular weight polymer solutions.

Simulation of single DNA molecule stretching and immobilization in a de-wetting two-phase flow over micropillar-patterned surface

“…The integration of BD simulation with flow/electrical field computation has been carried out to study DNA dynamics in hydrodynamic and electrokinetic flows. 3,5,7,[29][30][31][32] However, previous studies only focused on 2-D and static/steady-state fields. In this study, we develop a BD-CFD simulation technique for DNA in complex transient physical systems.…”