“Nanotechnology and Nanomaterials”

Heat transfer in complex flows of microfluids and nanofluids through minichannels of different shapes

V. Cherevko, N. Kizilova 
1Department of Aplied Mathematics, Kharkov National University. Svobody sq., 4, 61022 Kharkiv, Ukraine. 
E-mail: n.kizilova@gmail.com

The micro/nanofluids are suspensions of the micro/nano particles with diameters 10-500 in a base fluid. Due to high surface to volume ratio of the micro/nano particles, such fluids possess unique mechanical, thermal, acoustic, electric, and magnetic properties [1]. They are attractive candidates as circulating fluids in the fuel cells, microheaters/coolers, engines and microelectromechanical systems. A systematic study of the complex flows of immiscible micro/nano fluids in the pipes and channels of different cross sections revealed the flow resistivity can be significantly decreased and the volumetric flow rate increased by a proper choice of the fluid parameters and relative volumes [2]. Here a review of theoretical models of the heat conduction by steady flows of the micro/nano fluids in the circular, elliptic, triangle and rectangle tubes and annulus is presented together with corresponding experimental data. 
The incompressible Navier-Stokes and heat balance equations  

have been solved numerically with the second order velocity slip and temperature jump boundary conditions at the solid walls [1]. 
Numerical simulations have been carried out at wide ranges of the material parameters. The conditions for improvement of the performance of the flow systems for heat conduction and energy dissipation are obtained in the each geometry considered.
  
1.	Karniadakis G.E., Beskok A., Aluru N. Microflows and nanoflows: Funda-mentals and simulation. // Interdisc. Appl. Math. Series, - 2005. – 29. - P.51-77.
2.	Cherevko V., Kizilova N. Complex flows of immiscible microfluids and nanofluids with velocity slip boundary conditions. In: Nanophysics, Nanomaterials, Interface Studies, and Applications, Springer Proceedings in Physics , vol. 183, O. Fesenko, L. Yatsenko (eds.). – 2017. – P. 207–230.