Low Peclet number mass and momentum transport in microcavities

For the informed design of microfluidic devices, it is important to understand transport phenomena at the microscale. This letter outlines an analytically driven approach to the design of rectangular microcavities extending perpendicular to a perfusion microchannel for applications that may include microfluidic cell culture devices. We present equations to estimate the transition from advection- to diffusion-dominant transport inside cavities as a function of the geometry and flow conditions. We also estimate the time required for molecules, such as nutrients or drugs, to travel from the microchannel to a given length into the cavity. These analytical predictions can facilitate the rational design of microfluidic devices to optimize and maintain long-term, low Peclet number environments with minimal fluid shear stress. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4794058]