This work investigates the turbulent flow and particles deposition in Wavy duct flows. The v2f turbulence model was used for simulating the turbulent flow through the Wavy Channel. The instantaneous turbulence fluctuating velocities were simulated using the Kraichnan Gaussian random field model. For tracking particles in the fluid flow, the particle equation of motion was solved numerically. The drag, Saffman lift, Brownian, and gravity forces acting on a suspended particle were included in the particle equation of motion. The effects of duct wave amplitude and wave length on deposition of particles of different sizes were studied. A range of waves with different amplitudes and wave lengths were simulated. The particle tracking approach was validated for turbulent flow in a flat horizontal Channel where good agreement with previous studies was found. The presented results showed that the duct Wavy walls significantly increase the particle deposition rate.

Two different Channel entrance designs, code named Valley First (VF) and Peak First (PF), were experimentally visualized by means of smoke-wire visualization technique to observe their effects towards the stream wise counter-rotating vortices generated. The spanwise wavelength of the vortices was pre-set by modifying the leading edge. The investigation was carried out on the laminar boundary-layer flow in a rectangular Channel with one-sided Wavy surface that has amplitude a and wavelength l of 7.5 mm and 76 mm, respectively. The vortices in the Channel with VF design preserve farther downstream than those on the PF design, which might be caused by the large favorable pressure gradient between the entrance flat plate and the first peak location. The counter-rotating vortices could still be observed at non-dimensionalized stream wise distance c (=x/l) =2.47 for Reynolds number Re (=UH/ν) =9900 in Channel with VF design.For lower Re, the vortices could preserve further downstream. In contrast, in Channel with PF design, the structures were only visible clearly up to approximately c=1.32 for Re=4700 and c=0.39 for Re=5200.

In this research, the heat transfer behavior of a Wavy mini-Channel heat exchanger was studied. Using the experimental data of heat transfer, the convective heat transfer coefficients were estimated. Among numerous trials, the Nusselt number (Nu) best correlation is a linear function of Reynolds number (Re) independent of Prandtl number (Pr), and similar correlations for hot and cold sides were obtained. The coefficient range is 0. 01 to 0. 03 for different fluids. The previous experimental works verify this conclusion. Also, in the case of non-Newtonian fluids and nanofluids, the definition of Re is related to its rheological behavior. However, if the velocity profile is specified, it can be used to derive the relation between the Fanning friction factor (Cf) and Re. Here, a suitable velocity profile for Wavy configuration is used, and the experimental values of Re are estimated by the experimental pressure drop data. It is shown that the application of the derived relation between Cf and Re is preferred compared to the assumption of a circular pipe that is convenient for fluid mechanics studies. In addition, it is proved that if experiments with different fluids or relative waviness are done at similar flow rates, the U versus the Re plot can be used to compare heat exchanger performance.

In the present study, two cases of a microChannel heat sink are studied: i) with 50 Wavy Channels, and ii) with the addition of Wavy tubes. Also, the effect of nanofluid Ag/water-ethylene glycol 50% is investigated. ANSYS Fluent software was used to solve the equations expressed in the problem geometry. To solve the momentum equation, the second-order UPWIND method is used. Also, the SIMPLEC algorithm with a staggered pressure grid is employed to couple velocity and pressure fields. The results show that the addition of a microtube significantly increases the overall thermal coefficient of the system because despite the microtube and having two different geometries in a heatsink at the same time, the heat exchange between the body and the fluid increases so that in a flow without a microtube with Reynolds number 300, the average surface temperature is 315 , but the addition of a microtube reduces this temperature to 309 , which is equal to 6 degrees. Also, as the Reynolds number (Re) increases, the effect of increasing the concentration of nanoparticles enhances. The results demonstrate that the thermal entropy generation ( ) decreases at high values of Re. In addition, the decrease in frictional entropy generation ( ) due to the increase in nanoparticles is directly related to their concentration and independent of Re. So that the Percentage of decrease in friction entropy due to an increase in nanoparticle concentration relative to the pure fluid is equal to 1% for a concentration of 0.1% and 9% for a concentration of 1%. It is revealed that total entropy generation ( ) and  do not exhibit the same behavior.