A comprehensive analysis is made of the flow and heat transfer characteristics of mixed convection
in a channel with rectangular blocks attached on one channel wall. The flow geometry models the
cooling process of integrated chips of high-power densities mounted on a multi-layered printed circuit
board system. Extensive numerical solutions are acquired to the governing Navier-Stokes equations under
the Boussine~-fluid assumption. The fiuite thickness of the board is fuily accounted for; the conjugate
nature of the heat transfer within a single module is described. in an effort to move closer to realism, the
thermally-periodic boundary condition is imposed on the two successive plates. Details of the ffow and
thermal fields, for Reynolds numbers ranging from 100 to 1500 and Grashof numbers in the range of 0 to
2 x lo”, are presented for two representative cases, i.e. a horizontally-oriented channel and a verticallyoriented
channel. The behavior of the local Nusselt number along the block surfaces is portrayed. The
distributions of the temperature and of the heat transfer rate on the surface of the base plate are illustrated.
The trend of the maximum chip temperature vs Re is depicted. In light of the conjugate heat transfer
analyses of the present study, it is asserted that such oversimplified assumptions as the isothe~al or
adiabatic surface wall conditions may not be entirely appropriate for simulating the cooling of modem
electronic devices.