A critical review on pulsating flow in conventional fluids and nanofluids: Thermo-hydraulic characteristics

Abstract

In this review, an overview of pulsating flows with and without heat transfer is done. In addition to conventional fluids, the effects of using nanofluids are investigated. Using nanofluids instead of conventional fluids and application of pulsating flows instead of steady flows are two efficient approaches in increasing heat transfer. The impact of parameters such as nanofluid volume fraction, nanofluid type, pulsating frequency and amplitude, and Reynolds number on thermal and hydraulic attributes of pulsating flows are reviewed. The studies performed reveal a promising view to reach superior thermohydraulic characteristics by combining pulsating flows and nanofluids. With increasing the Reynolds number, the axial velocity increases, and thus, nanofluid mixing intensifies. This augments the mixing of hot fluid adjacent to walls and inlet cold fluid, and therefore, the rate of heat transfer improves. The researchers have used nanofluids in the form of metal oxide nanoparticles/water more than other nanofluids in this area. According to the fact that agglomeration of the nanoparticles has often been a serious problem in using nanofluids, employing pulsation in flows can significantly reduce occurrence of this problem and improve the stability of nanofluids. The existing challenges are introduced and future research requirements are recognized and projected.