wall heat flux. The Reynolds number was confined within the range
of 100e1500, and the amplitude of the surface was between 0 and
0.5. Their results showed that the shear stress and the Nusselt
number increase by increasing the Reynolds number and highest
magnitude occurs in the entrance area.
Castell~oes et al. [3] reported convective heat transfer enhancement
in low Reynolds number flows with wavy walls. They proposed
a hybrid numerical-analytical solution methodology for
energy equation. They achieved an illustrative sinusoidal corrugation
shape, and discussed on the influence of Reynolds number and
corrugation geometric parameters.
Metwally et al. [4] studied enhanced heat transfer due to
curvature-induced lateral vortices in laminar flow in sinusoidal
channels. They represented that increasing the Reynolds number
results in the increasing of both Nusselt number and skin friction.
Also, they found that in the non-circulating regime, the geometry of
the channel didn't have a significant effect on the heat transfer
enhancement. But in the circulating regime, flow separation and
reattachment grow with Reynolds number and aspect ratio.
Some researchers applied the single-phase or two-phase model
approach for the simulation of nanofluids. Manavi et al. [5] investigated
the turbulent forced convection of Al2O3-water nanofluid in
a wavy channel using two phase mixture model. The conducted
simulations revealed that by increasing the volume fraction of
nanoparticles, Reynolds number and amplitude of wall waves, the
rate of heat transfer is increased. Moreover, the results indicated
that the mixture model yields higher Nusselt numbers as compared
to the single phase model.
Heidary and Kermani [6] investigated the effect of nanoparticles
on laminar forced convection in sinusoidal-wall channel.
For simulation of nanofluids, they used single phase model and
found that adding nano-particles to pure fluid makes significant
increase in heat transfer. They used copper-water nanofluids with
volume fraction between 0 and 20% and Reynolds number in the
range of 5e1500.
Ahmed et al. [7] numerically investigated the heat transfer
enhancement in a wavy channel using nanofluid. They employed
single phase approach and their governing parameters were Reynolds
number and volume fraction in the range of 100e800 and
0e5%, respectively. It was observed that the enhancement of heat
transfer mainly depends on the nanoparticles volume fraction, the
amplitude of the wavy wall, and Reynolds number rather than the