Transverse vibration creates strong vorticity to the plane perpendicular to flow direction which leads to the radial mixing of fluid and, therefore, the results of heat transfer are significantly improved. Comparative studies of effects on heat transfer were investigated through a well-valid CFD model. Water and water-based nanofluid were selected as working substances, flowing through a pipe subjected to superimposed vibration applied to the wall. To capture the vibration effect in all aspects; simulations were performed for various parameters such as Reynolds number, solid particle diameter, volume fraction of nanofluid, vibration frequency, and amplitude. Temperature, solid particle diameter and volume fractiondependent viscosity have been considered; whereas, the thermal conductivity of nanofluid has been defined to the function of temperature, particle diameter and Brownian motion. Due to transverse vibrations, the thermal boundary layer is rapidly ruined. It increases the temperature in the axial direction for low Reynolds number flow that results in high heat transfer. As the Reynolds number increases, vibration effect is reduced for pure liquid, while there is noticeable increase for nanofluid. The rate of increment of heat transfer by varying volume fraction and particle diameter shows the usual feature as nanofluid under steady-state flow, but when subjected to vibration is much higher than pure liquid. As the frequency increases, the vibration effects are significantly reduced, and in amplitude they are profounder than frequency. The largest increase of about 540% was observed under the condition of vibrational flow compared to a steady-state flow.

A valid CFD model is employed to show the impact on heat transfer of one-dimensional laminar non-isoviscous flow through pipe subjected to forced transverse vibration. Through transverse vibration, which produces the chaotic fluid motion and swirling effects, adequate radial mixing across the tube can be achieved which leads to the great addition in heat transfer. Thermal boundary layer developed more quickly and thus, temperature profile developed wilder than steady flow under the effect of vibration in both radial and axial direction, considerably for low Reynolds Number; as Reynolds number increases that effectively reduced. In this study, these impacts are quantitatively exhibited for Newtonian and shear-thinning liquid at various Reynolds numbers; and found that application of superimposed vibrational flow limited to considerably for small: Reynolds number and flow behavior index of shear thinning fluids.

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Nanofluids has significant effect on heat transfer enhancement for comparatively high Reynolds number than to low Reynolds number flow. Whereas, vibration effects reduces in significance as Reynolds number increases. This study combined these two method of heat transfer enhancement i.e. use of nanofluid flow through pipe under vibration. A grid independent CFD model used for the study was validated in various aspects such as it was validated for variation of local Nusselt number, isothermal vibrational flow and non-isoviscous viscosity model so that one could believe the results obtained from the model. A valid CFD simulations has been done to investigate the effect on heat transfer to fluid flowing from pipe subjected to a constant heat flux. Al2O3-water based nanofluid was used as Newtonian fluid as it exhibits Newtonian behavior at low concentration (∅ < 2%). In order to make it non-Newtonian in nature, mixture of Al2O3 nanoparticles and 0.5 wt% aqueous CMC solution was used. Temperature dependent viscosity and thermal conductivity relations were considered for nanofluid so that it can be effectively model as single phase fluid including factors like liquid layering, Brownian motion etc. Simulations were done for different Reynolds number, volume fraction and solid particle diameter and results were presented in the form of ratio of heat transfer coefficient of vibration flow to steady-state flow. At low Reynolds number flow, a significant increment was observed for non-Newtonian nanofluid and its effect increases for volume fraction and solid particle than that of Newtonian nanofluid for the range of simulation parameters used.