Effect of side ratio on fluid flow and heat transfer from rectangular cylinders using the PANS method

Study of active flow control for a simplified vehicle model using the PANS method

Large Eddy Simulations (LES) were carried out to investigate the aerodynamic characteristics of a rectangular cylinder with side ratio B/D=5 at Reynolds number Re=22,000 (based on cylinder thickness). Particular attention was devoted to the effects of velocity shear in the oncoming flow. Time-averaged and unsteady flow patterns around the cylinder were studied to enhance understanding of the effects of velocity shear. The simulation results showed that the Strouhal number has no significant variation with oncoming velocity shear, while the peak fluctuation frequency of the drag coefficient becomes identical to that of the lift coefficient with increase in velocity shear. The intermittently-reattached flow that features the aerodynamics of the 5:1 rectangular cylinder in non-shear flow becomes more stably reattached on the high-velocity side, and more stably separated on the low-velocity side. Both the mean and fluctuating drag coefficients increase slightly with increase in velocity shear. The mean and fluctuating lift and moment coefficients increase almost linearly with velocity shear. Lift force acts from the high-velocity side to the low-velocity side, which is similar to that of a circular cylinder but opposite to that of a square cylinder under the same oncoming shear flow.

Prediction of unsteady flow around square and rectangular section cylinders using a discrete vortex method

Vortex shedding and heat transfer dependence on effective Reynolds number for mixed convection around a cylinder in cross flow

The flow of liquid metals around a near-wall cylinder and the enhancement of heat transfer in a duct under a magnetic field and high heat flux are investigated in this work using numerical simulations. The analysis of the heat transfer mechanism reveals three categories of dominant factors affecting mixed convection: vortex shedding, thermal buoyancy, and their coupled effects. A strong magnetic field can suppress flow instability, leading to three types of flow patterns: non-vortex shedding mode, regime I, and regime II. The position of the cylinder relative to the hot wall nonlinearly influences heat transfer efficiency and the global Nusselt number. When the cylinder is positioned closer to the hot wall, the distribution of the vortex to the wall shear layer effectively enhances heat exchange between the thermal boundary layer and the core flow region. Excessive proximity of the cylinder to the hot wall causes vortex asymmetry, which results in reverse Kármán vortex street formation and decreases heat transfer capability. An equation is provided to describe how cylinder position variations affect the thermal boundary layer thickness.

On the onset of vortex shedding from 2D confined rectangular cylinders having different aspect ratios: Application to promote mixing fluids

Acoustic streaming outside spherical particles and parameter analysis of heat transfer enhancement

In this study, a longitudinal pitch effect on in-line tube bank heat transfer has been analyzed numerically. To verify the accuracy of the solver model and boundary conditions, global Nusselt number(Nu) and pressure drop across the 2 row tube bank are compared with the existing experimental correlations under 500 ~ 2,000 Reynolds number(Re) range. By changing transverse pitch(<TEX>$S_T$</TEX>) or longitudinal pitch(<TEX>$S_L$</TEX>) separately in tube bank, we're trying to identify the each effect on heat transfer. We found that the effect of transverse pitch can be accounted for Reynolds number evaluated with maximum velocity(<TEX>$V_{max}$</TEX>) at the smallest flow area similar to most existing correlations. Variation of the longitudinal pitch(<TEX>$S_L$</TEX>) has a greater impact on the heat transfer compared to the transverse pitch(<TEX>$S_T$</TEX>). Overall Nusselt number increases with larger longitudinal pitch(<TEX>$S_L$</TEX>), however individual Nusselt number of the tube row has significant difference after the first row.

Rectangular Cylinder with a rectangular cross section is also used as a building, the architectural features of the building, the internal flow geometry, and beam. In addition, flow around Rectangular Cylinder can produce local instability and can lead to global instability. Diffuser can work for both conditions by reducing the drag force and increase down force. Diffuser is designed to change the fluid kinetic energy into potential energy in the form of pressure. The increase in pressure that occurs in the diffuser will generate a positive pressure gradient or also called adverse pressure gradient (APG). In this case Rectangular Cylinder that use Diffuser And Without Diffuser at Re 1 x 106 obtained graphs of: (a) Drag Coefficient (Cd) (b) Lift Coefficient (Cl) and (c) Velocity contour in the area of mid span numerically using the software Fluent 6.3.26 with k ε- turbulence models that Standard are two-dimensional (2D). On the Cylinder Rectangular diffuser values obtained using 1:36 Cd and Cl -0.81 and Rectangular Cylinder without diffuser obtained value Cd Cl 0:47 and 1:53, clearly visible on the use Rectangular Cylinder diffuser turns diffuser provides greater Cd and Cl negative or increase down force. The treatment is to eliminate the other side upper corner on the front of a quarter circle with r = 0.1, this produces a different contour velocity when compared experiment this treatment capable of eliminating reattached flow on the upper side area.

Vortex-induced vibrations of a rectangular cylinder

Effects of streamwise aspect ratio on the spatio-temporal characteristics of flow around rectangular cylinders

Numerical simulation of unsteady low-Reynolds number flow around rectangular cylinders at incidence

Aerodynamic interaction between galloping instability and vortices in corner-cut rectangular cylinders

Mathematical model of acrosswind dynamic loads on rectangular tall buildings

An experimental study of heat transfer has been conducted in a channel flow with rectangular cylinder having the various width-to-height ratio, b/h, of 0.5, 1, 2 and 3. The measurement of heat flux fluctuation at the channel wall and flow visualization of smoke-wire method with high speed video recordings were synchronized in order to investigate the relation between heat transfer enhancement and shedding vortices from the cylinder. It is clarified that heat transfer is augmented by the wall-ward flow which is induced by the clockwise and counter-clockwise vortices shed alternately from the cylinder.