Heat transfer in rough microchannels under rarefied flow conditions

Abstract

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.

Experimental investigation on convective heat transfer of Shear-thinning fluids by elastic turbulence in a serpentine channel

“…A few concepts have been proposed to induce turbulent-like flow in laminar flow regime including mechanical and structural methods [5][6][7][8][9] , which have limited success. Viscoelastic fluids, especially shear-thinning fluids and Boger fluids, have been recently found to be able to induce turbulence at the microscale due to the coiling and stretching of polymers inside, which is called elastic turbulence [10] .…”

Compressible Fanno flows in micro-channels: An enhanced quasi-2D numerical model for turbulent flows

“…Different types of slip boundary conditions were discussed and compared in [13], while in [14] the temperature jump boundary condition was investigated for the case of turbulent flow. Other works focus on friction factor [15] and heat transfer characteristics [16,17] in the slip flow regime.…”