| Abstract: | The viscous forces acting on a DNA macromolecule in a fiber are calculated. The DNA polymer is modeled as an infinite rod of elliptical cross section with a grooved surface. The viscous solvent is hydrodynamic water. Appropriate boundary conditions for determining the viscous forces on the acoustic vibrational modes are discussed. The viscous forces acting on each mode are then calculated as functions of both frequency and amount of water in the fiber. The mass loading of the DNA due to water in the grooves is shown to reduce the longitudinal acoustic velocity, which agrees with recent experimental results. The longitudinal modes are determined to be underdamped and correspondingly sharp over a range of frequencies and humidities appropriate to experimental conditions. The torsional and transverse acoustic modes are still strongly overdamped. |
