Steady and Pulsating Flow Past a Heated Rectangular Cylinder(s) in a Channel

Abstract

In the present study, the effect of laminar steady (Re=100, Pr=0.74) and pulsating flow (4 Hz and amplitude 0.4) is numerically studied over a centrally located heated rectangular cylinder of varying aspect ratio (W/H=1 to 8) in a confined channel using finite volume method. To study the influence of channel walls at a fix distance, eccentric placement of the highest aspect ratio cylinder(s) with two gap ratios (B/H) of 5 and 0.5 is done. Isotherms and streamlines of the flow are presented along with lift and drag coefficients. Further, FFT spectral analysis is performed to evaluate the vortex shedding frequency of the flow upon interaction with the cylinder(s). For single cylinder at the center position in the channel, natural vortex shedding and "lock-on" shedding occurs for lower aspect ratio cylinder under steady and pulsating flow, respectively. An increase in aspect ratio has a suppressi ng effect on the vortex shedding with a substantial decrease in the heat transfer over the cylinder. Placing two cylinders (W/H=8) at a geometrically symmetrical eccentric location of B/H=5shows an extra peak at half of the flow inlet frequency in FFT spectral curve that possibly confirms the "lock-on" shedding with increased heat transfer over the cylinder.

Imaging modalities to diagnose carotid artery stenosis: progress and prospect

“…Deriving the geometry features from the CTA and blood flow parameters from MRI [91], a patient-specific carotid hemodynamic can be studied using computational fluid dynamics (CFD) [92]. In the past, it is shown that CFD-based flow analysis can facilitate an accurate and early prediction of the plaque prone to rupture [93].…”

Study on Heat Transfer in Self-Excited Oscillation with Backflow Vortex Disturbance Effect

“…The study showed that the pulsation frequency, pulsation amplitude, and Reynolds number were the most direct parameters to characterize pulsation flow and heat transfer. Saxena and Ng [21] studied numerically the effect of both laminar steady and pulsating flow over a centrally located heated rectangular cylinder of varying aspect ratios, in a confined channel. The results showed that an increase in aspect ratio had a suppressing effect on the vortex shedding, with a substantial decrease in the heat transfer over the cylinder.…”

Carotid artery stenosis (CAS) disease detection by passive and active medical infrared (IR) thermal imaging

“…Given the group D3 has a wide range of stenosis degree cases (from 50% to near occlusion) and presence of multiple location stenosis in the CCA, ICA, and ECA region, it resulted in a high 95% CI velocity value. With the reduction in the diameter, from group C to D3, the blood flow velocity tends to increase, which is accompanied by the formation of recirculation zone past the stenosis and reduction in the adequate blood volumetric flow [124,222,223]. This affects the surrounding tissue heat transfer, which is expected to result in variational temperature features on the outer skin surface [178,182].…”

“…Deriving the geometry features from the CTA and blood flow parameters from MRI [123], a patient-specific carotid hemodynamic can be studied using computational fluid dynamics (CFD) [124]. In the past, it is shown that CFD-based flow analysis can facilitate an accurate and early prediction of the plaque prone to rupture [125].…”

“…With constant thermal properties, the 3D carotid artery blood flow was assumed to be Newtonian and incompressible [186]. The fluid flow and heat transfer were modelled by the Navier-Stokes and energy equations [124],…”