Heat transfer enhancement in a straight channel via a rotationally oscillating adiabatic cylinder

Abstract

Lock-in regime Time periodic flow and heat transfer a b s t r a c t Heat convection from the uniformly heated walls of a straight channel in presence of a rotationally oscillating cylinder (ROC) is simulated at Re ¼ 100. Heat transfer enhancement due to vortex shedding from the ROC is investigated. Systematic studies are performed to explore the rotation angle and frequency influences on heat transfer by varying the latter in range of the lock-in regime and the former from 0 to 2p/3. All simulation results are based on the numerical solutions of two-dimensional, unsteady, incompressible NaviereStokes and energy equations using an h/p type finite element algorithm. Considering time periodicity of the resulting flow and temperature fields, time averaged wall Nusselt number is reported to quantify the heat transfer enhancement for Pr ¼ 0.1, 1.0, 5.0 and 10.0 fluids. Performance analyses of the ROC device based on its total power consumption and heat transfer enhancement are also presented.

Convective heat transfer enhancement in a parallel plate channel by means of rotating or oscillating blade in the angular direction

“…In case 2, the force convection heat transfer from a stationary circular cylinder inside the channel was computed. As shown in Figure 5, the time averaged Nusselt numbers were compared with those of Beskok et al [11] and demonstrated good conformity.…”

“…In accordance to their results, transversely oscillating cylinder with 75% of the natural vortex shedding frequency had the best performance. Beskok et al [11] investigated the effect of oscillation angle and frequency of circular cylinder on heat transfer enhancement in a channel with heated walls at Re=100. They found that heat transfer enhancement could be achieved by increasing oscillation angle with a frequency equal to 0.8 of the cylinder natural frequency.…”

Combining an obstacle and electrically driven vortices to enhance heat transfer in a quasi-two-dimensional MHD duct flow

“…Hussam, Thompson & Sheard (2012b) reported that the optimum perturbations leading to Kármán vortex shedding are localized in the near-wake region around the cylinder, which can be excited by a cylinder oscillation. Studies have examined cylinder rotation about its own axis (Beskok et al 2012;Hussam, Thompson & Sheard 2012a), or oscillated in either a transverse direction (Yang 2003;Fu & Tong 2004;Celik, Raisee & Beskok 2010) or in line with the incident flow (Griffin & Ramberg 1976). The resulting vorticity field in all cases are similar, despite the different oscillation mechanisms (Beskok et al 2012).…”

“…Studies have examined cylinder rotation about its own axis (Beskok et al 2012;Hussam, Thompson & Sheard 2012a), or oscillated in either a transverse direction (Yang 2003;Fu & Tong 2004;Celik, Raisee & Beskok 2010) or in line with the incident flow (Griffin & Ramberg 1976). The resulting vorticity field in all cases are similar, despite the different oscillation mechanisms (Beskok et al 2012). It has been found that increasing oscillation amplitude leads to a higher convective heat transfer from a hot wall (Yang 2003;Beskok et al 2012), though the gains become more modest at larger amplitudes (Hussam et al 2012a).…”

Effect of cylinder proximity to the wall on channel flow heat transfer enhancement

“…Also, by increasing the non-dimensional rotational speed of the cylinder, both the Nusselt number and the drag coefficient decrease rapidly. In our last work [19], heat transfer enhancement in a channel via a rotationally oscillating cylinder was investigated. It was found that the maximum heat transfer was achieved when the oscillating frequency is 80% of the natural frequency of vortex shedding in presence of a stationary cylinder.…”