Verification of the heat transfer and friction factor of the AR=2
smooth channel without baffle is performed by comparing with the
previous values under a similar operating condition as shown in
Fig. 2a and b, respectively. The current numerical smooth channel
result is found to be in excellent agreement with exact solution values
obtained from the open literature [21] for both the Nusselt number
and the friction factor, less than±0.25% deviation. The exact solutions
of the Nusselt number and the friction factor for laminar flows over
AR=2 smooth channels with constant wall temperature are as
follows [21]: