The thermal flow characteristics of a ferrofluid under magnetic field effects in a microchannel were investigated with different patterned blocks of rectangular and triangular configurations, which were mounted on the top and bottom wall surfaces alternately. Also, the effects of external magnetic fields of different orientations on the thermal behaviors of the ferrofluid in the modeled microchannel were numerically investigated. The results showed that the external magnetic field critically affected the heat transfer performances of the ferrofluid because the generated pressure gradients of the ferrofluid flow changed with strength and orientation of the external magnetic field. Using these phenomena, we could control the heat transfer processes of the ferrofluid flow in the modeled microchannel. (C) 2014 Elsevier Ltd. All rights reserved.