In this thesis, the effects of varying amplitude-to-period ratio (A/P=0.15, 0.2 and 0.4) on turbulent flow and heat transfer in a wavy-channel at a fixed nominal Reynolds number Reb,nom=5600 have been studied by means of direct numerical simulation (DNS). The results of these flows are further compared with those of a plane-channel flow at a similar Reynolds number. The impact of the wavy wall on the turbulent transport of momentum and thermal energy has been thoroughly investigated through the analyses of the first- through fourth-order statistical moments of the velocity and temperature fields, joint probability density function (JPDF) of the velocity and temperature fluctuations, budget balance of both the turbulence kinetic energy (TKE) and turbulence scalar energy (TSE) transport equations, swirling strength iso-surfaces, 2-D spatial two-point cross- and auto-correlation coefficients of the velocity and temperature fluctuations, and pre-multiplied energy spectra of the velocity fluctuations. A separation region is observed in the wave troughs, resulting in a mean flow recirculation bubble where the convective heat transfer is greatly impacted. It is also observed that the wavy wall induces a strong shear layer at the wave peak that envelope the recirculation bubble and further enhances the transport of turbulence kinetic and scalar energy between the high-momentum hot outer flow and low-momentum cold near-wall flow. Furthermore, it is interesting to observe that as the wave steepness increases, the characteristic length scales of turbulence structures become increasingly shortened in the streamwise direction while aligning more prominently in the vertical direction. Analysis of key performance parameters such as the Nusselt number and total drag coefficient reveal that the thermohydraulic efficiency decreases as the value of A/P increases.