  Mitigation of hot spots in MEMS employing in situ microchannel systems
requires a comprehensive picture of the maldistribution of the working fluid
and uniformity of cooling within the same. In this article, detailed
simulations employing parallel micro channel systems with specialized
manifold-channel configurations i.e. U, I and Z have been performed. Eulerian
Lagrangian Discrete Phase Model and Effective Property Model with water and
alumina water nanofluid as working fluids have been employed. The distributions
of the dispersed particulate phase and continuous phase have been observed to
be, in general, different from the flow distribution and this has been found to
be strongly dependent on the flow configuration. Particle maldistribution has
been conclusively shown to be influenced by various migration and diffusive
phenomena like Stokesian drag, Brownian motion, thermophoretic drift, etc. To
understand the uniformity of cooling within the device, which is of importance
in real time scenario, an appropriate figure of merit has been proposed. It has
been observed that uniformity of cooling improved using nanofluid as working
fluid as well as enhanced relative cooling in hot zones, providing evidence of
the smart nature of such dispersions. To further quantify this smart effect,
real time mimicking hot-spot scenarios have been computationally probed with
nanofluid as the coolant. A silicon-based microchip emitting non-uniform heat
flux (gathered from real-time monitoring of an Intel Core i7 4770 3.40 GHz quad
core processor) under various processor load conditions has been studied and
evidence of enhanced cooling of hot spots has been obtained from DPM analysis.

Fluid Dynamics;Mesoscale and Nanoscale Physics