Papers presented to the 11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 20-23 July 2015.
A hybrid solver dynamically coupling kinetic solutions
computed in local rarefied areas and Navier–Stokes solutions in
the rest of the flow is used for the analysis of heat transfer in a
rough microchannel. Roughness geometry is modeled as a
series of triangular obstructions and a relative roughness up to
5% of the channel height is considered. Wide range of the
Knudsen numbers (from 0.01 up to 0.1) is considered, at low
Mach number (nearly incompressible flow). The competition
between roughness, rarefaction and heat transfer effects is
discussed in terms of averaged Nusselt and Poiseuille numbers
and mass flow rate. Discrepancy between the full Navier–
Stokes and hybrid solutions is investigated, assessing the range
of applicability of the first order slip boundary condition for
rough geometries with and without heat transfer.