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This study investigated the grouted sleeve splices and corrugated duct splices between shear walls and footing. In this regard, three shear walls were experimentally tested. One wall was cast monolithically with the foundation (RCWS), whereas two walls were precast. One wall was connected to the foundation using splice sleeves (PGWS), and another with corrugated duct splices (PCWS). All the walls were tested under reverse cyclic loading and a constant axial load. It was observed that the performance of specimen PGWS was controlled by rocking, and a premature connection loss was observed at one of the grouted sleeve splices. The hysteretic performance of specimen PCWS was close to that of specimen RCWS, whereas extensive pinching was observed in the hysteretic response of specimen PGWS. The peak load, ductility, secant stiffness, and energy dissipation of specimens RCWS and PCWS were in good agreement, whereas the energy dissipated by specimen PGWS was considerably lower than the corresponding values of specimens RCWS and PCWS. Nonlinear fiber-based modeling in OpenSees was performed using SFI-MVLEM elements. The predicted hysteretic response of the OpenSees model was in close agreement with the experimental response. [ABSTRACT FROM AUTHOR]

This study investigated the grouted sleeve splices and corrugated duct splices between shear walls and footing. In this regard, three shear walls were experimentally tested. One wall was cast monolithically with the foundation (RCWS), whereas two walls were precast. One wall was connected to the foundation using splice sleeves (PGWS), and another with corrugated duct splices (PCWS). All the walls were tested under reverse cyclic loading and a constant axial load. It was observed that the performance of specimen PGWS was controlled by rocking, and a premature connection loss was observed at one of the grouted sleeve splices. The hysteretic performance of specimen PCWS was close to that of specimen RCWS, whereas extensive pinching was observed in the hysteretic response of specimen PGWS. The peak load, ductility, secant stiffness, and energy dissipation of specimens RCWS and PCWS were in good agreement, whereas the energy dissipated by specimen PGWS was considerably lower than the corresponding values of specimens RCWS and PCWS. Nonlinear fiber-based modeling in OpenSees was performed using SFI-MVLEM elements. The predicted hysteretic response of the OpenSees model was in close agreement with the experimental response.

Abstract Structures of flow in a corrugated duct were experimentally examined employing the technique of Particle Image Velocimetry (PIV). The aspect ratio of the corrugated channel was selected as 0.3. Understanding the influences of phase shift, φ on the flow behavior and augmentation of heat transfer is one of the main objectives of this experimental work. Therefore, two different phase shifts such as φ = 0o and 90o and two different Reynolds Numbers, Re of 2 × 103 and 6 × 103 have been investigated for the available corrugated channel. In order to obtain the physics of the flow characteristics of the corrugated channel, the Turbulence Kinetic Energy, TKE, vorticity, and time-average velocity contours were calculated for both Reynold numbers, Re and phase shifts, φ. The experimental results revealed that transporting energy and increasing of momentum transfer by corrugated channel caused a better augmentation of the heat transfer rate for both phase shıft angles than the smooth channel. It appears that the turbulence generated by the sharp corner of the corrugated channels is the most influential factor in increasıng the entrainment between wake and core flows. [ABSTRACT FROM AUTHOR]

A forced convection flow and heat transfer of a water-based nanofluid with SiO2 particles with different volume fractions and nanoparticle diameters in corrugated ducts with different shapes are numerically studied. The three-dimensional governing equations are numerically solved in the domain by the control volume approach based on the SIMPLE technique. The effects of the nanoparticle diameter and shape on heat transfer is considered in the Reynolds number range 3000 ⩽ Re ⩽ 5000, and a uniform wall temperature is applied on the walls. The corrugated duct shape is optimized by the maximum performance evaluation criterion. [ABSTRACT FROM AUTHOR]

In this paper, flow and heat transfer characteristics of SiO2-water nanofluid flow over a corrugated backward-facing step are numerically investigated. The numerical study is performed by solving governing equations (continuity, momentum, and energy) with finite volume method. The duct inlet and step heights are 4.8 mm. The expansion ratio is 2. The upstream wall, Lu, and downstream wall, Ld, lengths are 48 cm and 96 cm, respectively. The downstream wall of the duct is subjected to a constant and uniform heat flux of 2000 W/m². The ranges of the volume fraction of nanoparticles and Reynolds number are 0%-3.0% and 135-240, respectively. The effects of the volume fraction of nanoparticles on the average Nusselt number, average Darcy friction factor, and velocity distribution are investigated under laminar forced convective nanofluid flow condition. It is revealed that the nanoparticle volume fraction substantially influences the heat transfer and flow characteristics. The volume fraction of 3.0% shows the highest heat transfer performance. [ABSTRACT FROM AUTHOR]

To create composite behaviour in precast concrete panel construction, grouted dowel connections are widely used owing to their simplicity and ability to divert damage from panels during excessive deformation. Yet, current design codes treat this connection as a bar-in-concrete idealization, disregarding the sleeve confinement and composite behaviour of the assembly. Moreover, the performance of this connection under cyclic excitation is yet to be explored. In this study, full-scale grouted dowel connection specimens mimicking actual field conditions were tested to failure under quasi-static loading. Experimental findings revealed that, regardless of the strain level, grouted connections consistently failed in a pull-through mode by shearing of grout between the lugs of the bar. For all dowel embedment lengths, the load capacity of connections depended primarily on the connection seams of the sleeve, and not on the hoop strain level developed in it. Measurement of the hoop strain values allowed calibrating the Frictional Model, which yielded satisfactory predictions of the experimental results. An empirical model was developed using the experimental results to capture the grout damage due to cyclic excitation, thus providing a rational and accurate design tool for grouted dowel connections in composite panel precast concrete wall construction. [ABSTRACT FROM AUTHOR]

Heat transfer enhancement in channel flow is investigated in the present study by using corrugated duct in lieu of smooth duct. In this regard, periodic different cavities are applied on the duct walls using the same aspect ratios. The values of the Reynolds numbers are in the range of 10,000 ≤ Re ≤ 20,000. The effects of the alumina-water nanofluid flow on the corrugated ducts are alternatively investigated by using the constant nanoparticle size for further improvement of the thermal characteristics. Computations are performed by means of finite volume approach on three different corrugated shapes. The effects of various parameters on the heat and fluid flow are also studied. The obtained results have revealed that the application of corrugated duct increases the rate of turbulent intensity on the central axis of the duct. In addition, it is found that the rate of heat transfer changes as a result of corrugated shape and Reynolds number. Furthermore, it is demonstrated that the application of the alumina-water flow in such ducts enhances the rate of the heat transfer and thermal performance when compared with the water flow. It is hoped that the obtained results will arouse interest towards thermal design. [ABSTRACT FROM AUTHOR]

The present study aimed at investigating the flow structure and heat transfer mechanism through the corrugated channel experimentally and numerically. Particle imaging velocimetry (PIV), which can give detailed information about the wake and shear flow regions, was used for the experiments. The experimental and numerical works were performed considering Reynolds numbers in the range of 6 × 103 ≤ Re ≤ 12 × 103 and 3 × 103 ≤ Re ≤ 2 × 104, respectively. In the numerical part, aspect ratios (R/h p) of examined grooves have been chosen as 0.1, 0.2, and 0.3, and for the experiment, only one aspect ratio was chosen which was 0.3. The experimental studies were conducted regarding different Reynolds numbers as well as the distributions of instantaneous and time-averaged velocity contours, Turbulence Kinetic Energy, Reynolds shear stress, and vorticity. The standard SST k-ω turbulent method was employed for the case of numerical study to predict the thermal performance (η) along with Nusselt numbers (Nu) the friction factors (f) and local field synergy angles (α, β) were calculated. As a result, the Nusselt number (Nu) values of the corrugated channels were higher than the parallel plate, and the increment in the Nusselt number initially increased and later decreased with Reynolds numbers for all aspect ratios considered. [ABSTRACT FROM AUTHOR]

Abstract: The present study investigates the flow and heat/mass transfer characteristics of wavy duct for the primary surface heat exchanger application. Local heat/mass transfer coefficients on the corrugated duct side walls are measured using a naphthalene sublimation technique. The flow visualization technique and a numerical analysis using a commercial code, FLUENT, are used to understand the overall flow structures inside the duct. The corrugation angle of the wavy duct is 145° and the duct aspect ratio is 7.3. The Reynolds numbers, based on the duct hydraulic diameter, vary from 100 to 5000. The results show that complex secondary flows and transfer processes exist inside the wavy duct resulting in non-uniform distributions of the heat/mass transfer coefficients on the duct side walls. At low Reynolds numbers (Re ⩽1000), relatively high heat/mass transfer regions like cell shapes appear on both pressure- and suction-side walls due to the secondary vortex flows called Taylor–Görtler vortices perpendicular to the main flow direction. However, at high Reynolds numbers (Re >1000), these secondary flow cells disappear and boundary layer type flow develop on pressure-side wall. On the suction-side wall, high heat/mass transfer region appears by the flow reattachment. The average heat/mass transfer coefficients are higher than those of the smooth circular duct and pressure drop increases due to the secondary flows inside wavy duct. [Copyright &y& Elsevier]