Milad Shakeri Bonab - Department of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran
Abolfazl Anarjani Khosroshahi - Department of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran
Mehdi Ashjaee - Department of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran
Seyed Farshid Chini - Department of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran

The effect of utilizing superhydrophobic walls on improving the convective heat transfer in a rectangular heatsink has been studied numerically in this paper. The vertical walls were kept at isothermal hot-and-cold temperatures and horizontal walls were insulated. The boundary condition on the walls was: no-slip for regular, and slip (with slip length of 500 µm) for superhydrophobic walls. By changing the heatsink aspect ratio (AR, height/width) from 0.1 to 10, it was observed that regardless of the wall slip, the optimum AR is 1, i.e. square enclosure. For a square heatsink, using the nanofluid with  = 3% could enhance the heat transfer (quantified by Nusselt number) by up to 9.8%. For the same enclosure filled with pure water, applying superhydrophobic horizontal walls could increase the heat transfer by 4.45%. The joint effect of using superhydrophobic walls and nano-particles enhanced the heat transfer by up to 14.75%. The results of this paper may open a new avenue for high performance cooling systems.

Natural convection, Heatsink, Local Cooling, nanofluid, Superhydrophobic, Slip Length