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We simulate DNA suspension microchannel flows using the dissipative particle dynamics (DPD) method. Two developments make this simulation more realistic. One is to improve the dynamic characteristics of a DPD system by modifying the weighting function of the dissipative force and increasing its cutoff radius, so that the Schmidt number can be increased to a practical level. Another is to set up a wormlike chain model in the DPD framework, according to the measured extension properties of a DNA molecule in uniform flows. This chain model is then used to study flows of a DNA suspension through microchannels. Interesting results on the conformation evolution of DNA molecules passing through the microchannels, including periodic contraction-diffusion microchannels, are reported.

In this paper, the effects of size of the chains composed of the drop and initial velocity of the drop on the drop terraced spreading are studied. The chain size effects on the base radius of drop are studied at zero initial velocity. A logarithm dependence of the drop base radius on the time is found for 2-atom to 16-atom flexible chain systems with large lattice dimension of solid and a power law t1/2 for small lattice dimension of solid. The longer the chain, the slower is the spreading. With a nonzero initial velocity, the drop base radius increases with increasing initial velocity before the drop splits into smaller separated drops. As the initial velocity increases, the transition from a logarithm to a power law t1/2 relation for the time dependence of the drop base radius is first noted here.