Accession Number:

ADA523702

Title:

Computations of Chaotic Flows in Micromixers

Descriptive Note:

Journal article

Corporate Author:

NAVAL RESEARCH LAB WASHINGTON DC LAB FOR COMPUTATIONAL PHYSICS AND FLUID DYNAMICS

Report Date:

2005-01-01

Pagination or Media Count:

4.0

Abstract:

Microfluidic devices are important components of chemical and biological sensors proposed for many Naval and civilian applications. The problem of controlling fluid mixing in microdevices is often critical to their successful operation. This is especially true for cases involving chemical reaction, in which the reactants and products must be delivered to selected target locations within a specified concentration range. Flows in these devices are laminar low Reynolds number, and mixing is controlled by the relatively slow process of molecular diffusion. An important practical issue is how to modify the flow to speed up the mixing process. One method used to enhance mixing is surface patterning, in which structures are placed along one or more surfaces of a channel. Stroock et al. have shown that repeating sequencies of bas-relief herring-bone-shaped structures on the floor of a microchannel create flow patterns that increase the interface area between the fluids to be mixed. The geometrical arrangement of obstacles stretches and folds the fluid, so that surface area between fluids is increased and mixing is enhanced. This phenomenon is called chaotic advection. We are working on a joint computational and experimental effort to design and build microreactors with enhanced and controlled mixing and surface delivery capabilities. In the work described here, we have used numerical simulations to study chaotic advection and focus on the Stroock et al. mixer. The numerical model solves the three-dimensional incompressible Navier-Stokes equations coupled with an equation that describes the advection of a passive scalar, such as a marker dye.

Subject Categories:

  • Fluid Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE