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The laminar natural convection in supercritical fluid along vertical flat plate with uniform heat flux was simulated in the present work. The governing equations of partial differential equations were solved numerically using the finite difference method. The thermo-physical properties calculation was based on a Van der Waals equation of state. The velocity and temperature profiles were solved with a FORTRAN code. HydrofluorocarbonsR134a, R1234yf and R404a were used as working fluids. Thermal expansively at a reduced pressure and reduced temperature near critical point (Pr and Tr = 1.05, 1.1) showed sharp variation. The local Nusselt number as a function of the local Rayleigh number was plotted. The curve trend illustrates that the Nusselt number decreases as the reduced pressure and reduced temperature increases. The corresponding curves of supercritical conditions depict the same shape of the corresponding line of classic correlation.The velocity and temperature developing along the vertical plate was plotted and contour lines explained the fluid behavior above supercritical conditions.

Sometimes, due to design mistakes or a change in the construction function results in heavier or additional loads, a flat slab may be failed by punching shear which is considered as a brittle failure. A lot of research work has been carried with the objectives of strengthening existing flat slabs against punching shear. Nevertheless, very few experimental tests have been conducted for the investigation of the behavior of repaired flat slabs damaged due to punching shear. An experimental investigation with the objective of retrofitting flat slabs damaged due to punching shear using prestressed vertical bolts is presented in this paper. The parameters examined in this study are vertical prestressed bolts with different ratios within the slab thickness, slab thickness and central column size. Through the experimental tests the load carrying capacity, deformation characteristics and the cracking behavior have been investigated. A comparison between the behavior of retrofitted slabs and their references showed that the proposed system of repair is effective and could be used in practice. A comparison between the experimental results and calculated punching failure load based on the formulas adopted by different codes, showed a reasonable agreement.

The falling and settling of solid particles in gases and liquids is a natural phenomenon happens in many industrial processes. This phenomenon has altered pure forced convection to a combination of heat conduction and heat convection in a flow over a plate. In this paper, the coupling of conduction (inside the plate) and forced convection of a non-homogeneous nanofluid flow (over a flat plate) is investigated, which is classified in conjugate heat transfer problems. Two-component four-equation non-homogeneous equilibrium model for convective transport in nanofluids (mixture of water with particles

This work concerns with experimental and numerical study for the cooling characteristics of a target plate under the effect of air impingement from orifice of different sizes D of (5,10,15 and 20 mm). A centrifugal blower was used for air impinging with jet velocity in the range (18-40 m/s). Tested Reynolds number Re is in the range of (7100-44400) with orifice to plate spacing ratio H/D of (2,4,6,8). Numerical analysis using CFD commercial code Fluent version 14.5 with K-ε RNG turbulence model has been used to simulate the flow and heat transfer in impingement jet. Both numerical and experimental results are analyzed to determine the effect of using different orifice sizes on heat transfer rates and flow structure on the target plate. A correlation is obtained for the stagnation Nusselt number as a function of Re and H/D. Optimum heat removal rate are found to occur at H/D=6. According to the experimental results which indicates that orifice diameter and jet velocity are the most effective variables which characterize the heat removal rate, a control system is designed and constructed to vary the orifice diameter in order to control the air flow rate and the plate temperature. Fixing the optimum H/D and for the used blower characteristics the control system is tested and the results show a good response for the control system for different operation conditions so that the cooling rates are increased for the heated plate.

At specific velocities, intense tonal sound can be radiated from the flow around cascaded flat plates. This sound arises from the coupled phenomena of vortex shedding and acoustic resonance. To suppress such noise, we actively control the vortex shedding and acoustic radiation by oscillating the edges of every second plate in the cascade. The objective of this investigation was to clarify the effects and mechanism of noise reduction under this control. To understand how the amplitude and frequency of the oscillations influence the controlled flow and acoustic fields around the flat-plate cascade, we conducted direct aeroacoustic simulations using the volume penalization method. The sound pressure level at the resonance frequency was decreased by oscillating the plates at a dimensionless amplitude of 0.15. The pressure reduction failed at oscillation frequencies close to the resonance frequency, because the acoustic resonance occurs at the oscillation frequency. In the audible range of oscillation frequencies (0–20 kHz), the audible overall sound pressure level was not able to be reduced. In contrast, at oscillation frequencies beyond the audible range, both the tonal sound pressure level at the resonance frequency and the audible overall level were decreased. Consequently, the noise radiated from a cascade of plates can be reduced by forced oscillations at a frequency above the audible range. Moreover, we offset the phase of the oscillations between two plates and observed the effect on the acoustic field. At a one-quarter phase offset, the sound pressure level at the oscillation frequency exhibited a vertical asymmetrical directivity. [ABSTRACT FROM AUTHOR]

The buckling capacity of uniformly compressed flat plates has been investigated in this study. Material properties were characterized based on parameterization of the stress-strain curves using a simple and novel mathematical expression. Idealized stress-strain relationships were developed using the proposed material model and extensive parametric numerical analyses were conducted to investigate the effect of the material stress-strain properties on the buckling capacity of flat plates. For stress-strain curves with a yield plateau, the results of the parametric study showed a minimal influence of the material properties on the buckling capacity of the plates whereas a significant effect of the strain-hardening properties was observed in plates with round-house curves. Ultimately, the proposed stress-strain model was shown to be remarkably useful for capturing the relevant intricacies associated with material nonlinearity when predicting the buckling capacity and post-buckling behavior of uniformly-compressed flat plates. [ABSTRACT FROM AUTHOR]

The thermal performance of a solar air heater is presented with addition fins. In this work, we developed an experimental study on the thermal performance of a solar collector air with and without semi-cylindrical baffle. In trying to change the mass flow rates times for both configurations corresponding to tilt angle β = 37 °, it represented the optimum tilt angle of the city of Biskra. The essential parameters are measurements of the outlet, an inlet and an ambient temperature and covering according to the influence of the wind velocity. Experiments on a solar collector designed for this purpose, have determined the thermal efficiency of solar collector with and without semi-cylindrical baffle to different flow intervals to actually follow the evolution of the outlet temperature of the air. The results provide the best thermal efficiency for a solar collector flat plate with semi-cylindrical baffle is increased by 19% that of without baffle. [ABSTRACT FROM AUTHOR]

This article investigates the dynamic stall of a pitching flat plate in order to facilitate lift control in applications such as flapping wings and micro-aerial vehicles. Constant-pitch-rate rotation, similar to ramp-and-hold, of a flat plate was investigated in an open-jet wind tunnel using embedded surface pressure sensors to assess vortex formation and its impact on aerodynamic characteristics. Three leading edge and trailing edge geometries were investigated, with all demonstrating minor effects on the overall aerodynamic performance for the angles of attack presented. For all leading and trailing edge combinations, increasing the rotation rate increased the magnitude of the localised low pressure on the upper surface the flat plate resulting in increased lift. Separation of the leading-edge vortex was characterised by the motion of a half-saddle flow feature on the upper surface of the flat plate, which in turn was linked to the rotation rate. A critical angle of attack was found whereby further increases in the angle of attack provided no benefit to overall force generation. The surface pressures shown in the current investigation can be utilised for the development of adaptive boundary layer control devices to either limit or promote the dynamic stall process on a flat plates. This study confirms that vortex lift, which is critical for flight of micro-aerial vehicles and flapping wing devices, is limited by the maximum angle of attack and rotation rate. This is significant for high-lift devices where limited power is available for lift generation. [ABSTRACT FROM AUTHOR]

The prospect of harvesting energy from flow-induced vibration using an elastic square cylinder with a detached flat plate is experimentally investigated. The feasibility of flow-induced vibration to supply an adequate base excitation for micro-scale electrical power generation is assessed through a series of wind tunnel tests. The current test model of a single square cylinder is verified through a comparable pattern of vibration amplitude response with previous experimental study and two-dimensional numerical simulations based on the unsteady Reynolds averaged Navier–Stokes (URANS). In addition, a downstream flat plate is included in the wake of the square cylinder to study the effects of wake interference upon flow-induced vibration. A downstream flat plate is introduced as the passive vibration control to enhance the magnitude of flow-induced vibration and simultaneously increases the prospect of harvesting energy from the airflow. The study is conducted by varying the gap separation between the square cylinder and flat plate for 0.1≤ G/D ≤3. The highest peak amplitude is observed for the gap G/D = 1.2 with yrms/D = 0.46 at UR = 17, which is expected to harvest ten times more energy than the single square cylinder. The high amplitude vibration response is sustained within a relatively broader range of lock-in synchronization. Meanwhile, for G/D = 2 the vibration is suppressed, which leads to a lower magnitude of harvested energy. Contrarily, the amplitude response pattern for G/D = 3 is in agreement with the single square cylinder. Hence, the flat plate has no significance to the wake interference of the square cylinder when the gap separation is beyond 3D. [ABSTRACT FROM AUTHOR]

Experiments on the convective heat transfer from a flat plate, vertically mounted and parallel to the flow in a wind tunnel, were carried out via Infra-Red thermography and hot-wire anemometry. The Reynolds number based on the inflow velocity and on the length of the plate was about 5 × 10 5 . A step near the leading edge of the plate was used to promote transition to turbulence, with tripping effects on the heat transfer coefficients shown to be negligible for more than 90% of the plate’s length. Different types of grids, all with same blockage ratio σ g = 28 % , were placed upstream of the plate to investigate their potential to enhance the turbulent heat transfer. These grids were of three classes: regular square-mesh grids (RGs), single-square grids (SSGs) and multi-scale inhomogeneous grids (MIGs). The heat transfer coefficients at the mid-length of the plate were correlated with the mean velocity and the turbulence intensity of the flow at a distance from the plate at which the ratio of the standard deviations of the streamwise and wall-normal velocity fluctuations began to increase. However, the heat transfer was shown to be insensitive to the turbulence intensity of the incoming flow in close proximity of the tripping step. Furthermore, the integral length scale of the streamwise turbulent fluctuations was found not to affect the heat transfer results, both near the tripping step and in the well-developed region on the plate. For the smallest plate-to-grid distance, the strongest heat transfer enhancement (by roughly 30%) with respect to the no-grid case was achieved with one of the SSGs. For the largest plate-to-grid distance, the only grid producing an appreciable increase (by approximately 10%) of the heat transfer was one of the MIGs. The present results demonstrate that MIG design can be optimised to maximise the overall heat transfer from the plate. A MIG that produces a uniform transverse mean shear, which is approximately preserved over significant downstream distances from the grid and with a velocity decreasing with distance from the plate, allows a sustained heat transfer enhancement, in contrast to all other grid designs tested here. The most efficient configuration for a MIG is one for which the section of the grid that has lower blockage and thicker bars is adjacent to the plate. [ABSTRACT FROM AUTHOR]

This study investigates the heat transfer capability between the near-wall water and a heating flat surface under the low frequency ultrasonic waves. The experiment was conducted at the main stream velocities of 0.12, 0.14, and 0.17 m/s, corresponding with the local Reynolds number between 60,000 and 200,000. The ultrasound, having a frequency of 25, 33, and 40 kHz was released from a 60 W flat transducer in a downward direction to disturb a near-wall flow over the flat surface having a constant heat flux of 1875 W/m 2 . The temperature decrease due to the disturbance of ultrasound, detected by 7 thin-leaf thermocouples, led to the increase in the Nusselt number by up to 10%, 16.5%, and 20.8%, at the wave frequency of 25, 33, and 40 kHz, respectively. The use of the thermochromic liquid crystals on the heating surface, disturbed by the 40 kHz wave, revealed that the bound of the wave incident region was shaped like a spiky structure that alternately occurs following with time. This incident region moved further downstream when the mainstream velocity increased and caused a retardation of the near wall flow, leading to a worse heat transfer in the upstream region. Therefore, the inclination of the acoustic beam, occurring as a variation of mainstream velocity, must be considered in order to use the ultrasound to enhance the heat transfer. Finally, the predictive formulas for the local Nusselt number under the 25–40 kHz waves are also provided and the mechanism of heat transfer is discussed. [ABSTRACT FROM AUTHOR]

In recent years, marine transportation as well as land and air transportation has become in the centre of attention. There has been an attempt to reduce the drag exerted on vessels by various methods, such as rough surfaces and base bleed. Study of the high-speed seawater animals like sharks and dolphins has triggered the use of riblets on the hull of marine vessels. The use of riblet is easy among various methods of skin friction drag reduction. For this reason, there is an interest for construction and optimization of riblet as an efficient and economical way. In this research, the shark's skin was modeled for the first time in ANSYS CFX using Computational Fluid Dynamics, through analyzing the effects of riblet on a submerged flat plate. Different types of riblet based on height and space between micro channels were studied, and then a comparison between a riblet-covered plate and a smooth plate in various velocities were performed. It was found that by selecting the most appropriate type of riblet, 11 % drag reduction can be attained. Then, by comparing different types of riblets, the best type for drag reduction was selected. Furthermore, the obtained results were compared with the available experimental data. [ABSTRACT FROM AUTHOR]

This paper presents the investigation of modal parameters using the different approaches. The object of the examination is the simple structure such as flat rectangle plate is. Before starting the measurement, there have been calculated natural frequencies of the plate by analytical approach. Subsequently, the experiment part is performed. The appropriate measuring apparatus has to be applicated for the experimental analysis. First, there are evaluated modal parameters of the specimen, the so-called "frequency sweep" is used as the input signal for excitation. After that, the experimental harmonic analysis is performed according the obtained eigen frequencies from the modal analysis. In the final stage, the data from simulations and experimental measurement are compared. [ABSTRACT FROM AUTHOR]

Film cooling effectiveness on flat plates with double rows of holes has been studied experimentally and numerically in this paper. This configuration is widely used to simulate the multi-row film cooling on turbine vane. Film cooling effectiveness of double rows of holes and each single row was used to study the accuracy of superposition predictions. Method of stable infrared measurement technique was used to measure the surface temperature on the flat plate. This paper analyzed the factors that affect the film cooling effectiveness including hole shape, hole arrangement, row-to-row spacing and blowing ratio. Numerical simulations were performed to analyze the flow structure and film cooling mechanisms between each film cooling row. Results show that the blowing ratio within the range of 0.5 to 2 has a significant influence on the accuracy of superposition predictions. At low blowing ratios, results obtained by superposition method agree well with the experimental data. While at high blowing ratios, the accuracy of superposition prediction decreases. Another significant factor is hole arrangement. Results obtained by superposition prediction are nearly the same as experimental values of staggered arrangement structures. For in-line configurations, the superposition values of film cooling effectiveness are much higher than experimental data. For different hole shapes, the accuracy of superposition predictions on converging-expanding holes is better than cylinder holes and compound angle holes. For two different hole spacing structures in this paper, predictions show good agreement with the experiment results. [ABSTRACT FROM AUTHOR]

Summary: This paper presents theoretical studies on load‐bearing capacity of reinforced concrete flat‐plate framed structures. The existing methods for determining load‐bearing capacity of simply supported slabs are first reviewed, and their limitations are presented. An energy‐based refined method is then proposed to enhance the accuracy of the existing methods by considering the contributions to internal energy dissipation due to the extension of reinforcing bars along yield lines, the additional resultant bending moment from membrane forces, and the sectional bending moment along yield lines of slabs. The refined method for simply supported slabs is extended for fixed supported slabs, and thus, the load‐bearing capacity of reinforced concrete flat‐plate structures subject to a middle column loss is analytically determined. The performance of the proposed method is validated against test results and also verified against finite element analyses. Parametric studies are conducted to investigate the effect of reinforcement ratio, slab thickness and aspect ratio on the stiffness, and yield‐line resistance of structures. It is found that for the fixed supported slabs, it is reasonable to assume negative yield lines along the slab edges to consider the effect of obvious concrete crushing along the edge. Square slabs have higher ultimate loads than rectangular slabs, due to a longer horizontal yield line in the middle in the rectangular slab, which has detrimental effect on the sectional ultimate bending moment. The numerical results show that the reinforcement ratio has little effect on the initial bending stiffness and yield‐line resistance of slabs for a given slab thickness and aspect ratio. The initial stiffness and yield‐line resistance increase as the slab thickness increases. For the same reinforcement ratio and slab thickness, a larger aspect ratio leads to a lower initial bending stiffness, yield‐line resistance, and stiffness in tensile membrane action stage, due to a longer yield line along which tensile membrane forces have a detrimental effect on the sectional bending moment. [ABSTRACT FROM AUTHOR]

The concept of an evacuated flat plate (EFP) collector was proposed over 40 years ago but, despite its professed advantages, very few manufacturers have developed commercial versions. This situation suggests both technical difficulties in manufacturing a competitively-priced sealed for life panel and a lack of awareness of the benefits of such panels. This paper demonstrates an evacuated flat plate simulation that closely models experimental efficiency measurements. Having established the validity of the model, it compares published data for a commercial EFP collector with predictions for an optimal design to investigate whether any further efficiency improvement might be possible. The optimised design is then evaluated against alternative solar energy devices by modelling a number of possible applications. These comparisons should inform choices about solar options for delivering heat: EFP collectors are well-suited to some of these applications. Evacuated flat plate collectors are a possible alternative to concentrating collectors for Organic Rankine Cycle power generation. The annual output for all the modelled collectors was found to be a quadratic function of delivery temperature: this enabled a novel optimisation of ORC source temperature. Predictions for concentrating and non-concentrating ORC plant are compared with a PV/thermal alternative. The ORC output is significantly less than a PV panel would achieve; applications needing both heat and power are better served by PVT panels. This is an original and novel result. [ABSTRACT FROM AUTHOR]

The concept of an evacuated flat plate collector was proposed over 40 years ago but, despite its professed advantages, very few manufacturers have developed commercial versions. This paper demonstrates the reduction in heat loss coefficient and increase in efficiency resulting from evacuating a flat plate collector: it is hoped that these results will stimulate interest in the concept. Evacuated tubes are now mass-produced in large numbers; evacuated flat plate collectors could in principle replace these tubes if the technical difficulties in creating extended metal-glass seals can be overcome. The experimental experiences described here should indicate targets for future research. Two different designs of evacuated flat plate solar thermal collector, each with a 0.5 × 0.5 m flooded panel black chrome plated absorber, were tested under a solar simulator. The cover glasses were supported by an array of 6 mm diameter pillars. Inlet and outlet temperatures were monitored via PT100 RTDs and glass temperatures were measured using thermocouples. Inlet temperature was controlled by a fluid circulator connected to a header tank with a Coriolis mass flow meter to measure fluid flow rate. Testing was conducted indoors with and without the use of a fan to cool the top cover glass. The test conditions spanned the range 200 < G < 1000 W/m 2 , 0 ⩽ T M ⩽ 52 ° C . Evacuating the enclosure reduced the measured heat loss coefficient by 3.7 W/m 2  K: this was a close match to predictions and corresponds to an increase in aperture efficiency from 0.3 to 0.6 at T M / G = 0.06 m 2 K / W . The poor efficiency under non-evacuated conditions was due to the black chrome absorber coating being less selective than commercial panel coatings. The solder seals were developed from experience with vacuum glazing but the increased gap led to reliability issues. A vacuum pump maintained the enclosures under a high vacuum (<0.1 Pa) during testing. The enclosure based on a thin rear metal tray proved to be more effectively sealed than the more rigid enclosure with glass on both sides: the latter developed leaks as the front to rear temperature difference increased. The biggest challenge in the manufacture of evacuated flat plate collectors is to ensure a long-term hermetic seal such that no pumping is required. [ABSTRACT FROM AUTHOR]

In view of the characteristic of Photovoltaic (PV) conversion, an experimental study has been conducted to investigate the natural convection heat transfer from a flat plate. In order to simulate the real PV cells, three electrical heating circuits were employed to achieve a linear nonuniform heat flux boundary condition. The major parameters, such as the gradient parameter of heat flux k, tilt angle θ and heat flux q were introduced to analyze their influence on heat transfer ability. Both the local temperature distribution and the overall trend of Nusselt number have been presented. Comparing with the uniform thermal boundary condition, the results show that the local convection heat transfer coefficient is fluctuated at the positions where heat flux has changed. When gradient parameter of heat flux increases, the difference of local convection heat transfer coefficient at the top of the plate between tilt angle θ = 0° and 90° becomes smaller. Moreover, it is observed that the gradient parameter of heat flux has a promotion effect on average convection Nusselt number at larger tilt angle, but the effect becomes complex as tilt angle is smaller. Finally, a correlation combining all significant factors has been put forward to estimate the natural convection heat transfer. [ABSTRACT FROM AUTHOR]

Laminar boundary layer flow over an infinite-span, finite-length flat plate is investigated in the regime of strong interaction with a hypersonic gas flow. Under the assumption that an additional condition dependent on the transverse coordinate can be imposed on the trailing edge of the plate the flow functions are expanded in power series in the vicinity of the leading edge. It is shown that these expansions include an indefinite function dependent on the transverse coordinate. The corresponding boundary value problems are formulated and solved and the eigenvalues are determined. It is established that in this case the two-dimensional boundary layer can rearrange itself into a three-dimensional boundary layer. [ABSTRACT FROM AUTHOR]

In this study, the effect of pressure gradient have been included for heat transfer in the boundary layer flow of Maxwell fluid over a flat plate.The solution of the problem is obtained with an application of algorithms of Adams Method (AM) and Gear Method (GM) with Homotopy Perturbation Method (HPM) as an approximation technique. This technique shows the outcomes of pressure gradient (m), Deborah number (α) and Prandtl number (Pr) in the boundary layer flow on temperature and velocity profiles, also the momentum and thermal boundary layer thickness and discussed. To obtain this objective, the momentum and energy equations of Maxwell are solved. The outcomes of HPM in the absence of relaxation time (λ) or Deborah number (α) and pressure gradient (m) (i.e. λ = α = m = 0) at Prandtl number Pr = 1 are in closed relation with the numerical results having the value of n∞1 is around 5. Also it is found that the system is convergent, as a whole momentum and thermal boundary layer thicknesses becomes thinner and thinner. Importantly, some cooling effects of the Maxwell fluid over a flat plate for energy profile have been observed. [ABSTRACT FROM AUTHOR]

Reinforced concrete flat plates consist of slabs supported directly on columns. The absence of beams makes these systems attractive due to advantages such as economical formwork, shorter construction time, less total building height with more clear space and architectural flexibility. Punching shear failure is usually the governing failure mode of flat plate structures. Punching failure is brittle in nature which induces more vulnerability to this type of structure. To analyze the flat plate behavior under punching shear, twelve finite element models of flat plate on a column with different parameters have been developed and verified with experimental results. The maximum range of variation of punching stress, obtained numerically, is within 10% of the experimental results. Additional finite element models have been developed to analyze the influence of integrity reinforcement, clear cover and column reinforcement. Variation of clear cover influences the punching capacity of flat plate. Proposed finite element model can be a substitute to mechanical model to understand the influence of clear cover. Variation of slab thickness along with column reinforcement has noteworthy impact on punching capacity. From the study it has been noted that integrity reinforcement can increase the punching capacity as much as 19 percent in terms of force and 101 percent in terms of deformation. [ABSTRACT FROM AUTHOR]

The post-tensioned (PT) flat plate slab system is commonly used in practice, and this simple and fast construction method is also considered to be a very efficient method because it can provide excellent deflection and crack control performance under a service load condition and consequently can be advantageous when applying to long-span structures. However, a detailed design guideline for evaluating the lateral behavior of the PT flat plate slab system is not available in current design codes. Thus, typical design methods used for conventional reinforced concrete (RC) flat plate slab structures have inevitably been adopted in practice for the lateral load design of PT flat plate structures. In the authors' previous studies, the unified equivalent frame method (UEFM) was proposed, which considers the combined effect of gravity and lateral loads for the lateral behavior analysis of RC flat plate slab structures. The aim of this study is to extend the concept of the UEFM to the lateral analysis of PT flat plate slab structures. In addition, the stiffness reduction factors of torsional members on interior and exterior equivalent frames were newly introduced considering the effect of post-tensioning. Test results of various PT flat plate slabcolumn connection specimens were collected from literature, and compared to the analysis results estimated by the extended UEFM. [ABSTRACT FROM AUTHOR]

Effusion cooling can be one of the attractive methods of cooling in a current high-efficiency gas turbine which has a very hot gas temperature above 1600 °C. For higher effectiveness of the air cooling for a gas turbine vane and blade, the air-cooled flow through effusionholes should not overshoot into the mainstream flow but still remain within the mainstream boundary layer. The present study is intended to examine flow structure of a microscale effusion cooling for gas turbine applications through flow visualization which is highly effective to obtain better understanding of the flow physics. The air flow through effusion-holes can be visualized with an oil atomized droplets, a laser-sheet and a high-speed CCD imaging system. The qualitatively visualized results show their flow patterns and characteristics with different effusion hole size and blowing ratio for effusion cooling. A series of vortical structure can be observed within the boundary layer along the microscale effusion flat plate which provided that the effusion cooling can be a plausible candidate up to the effusion-hole size of 0.7 mm. [ABSTRACT FROM AUTHOR]

Flat plates were designed and built in the early twentieth century without sensitivity to earthquake demands. The test reported was made to study the lateral stiffness, strength, and drift limit in one direction of a three-story, two-bay, full-scale reinforced concrete flat-plate building proportioned to resist gravity loading only. The focus of the experiment was on three issues: 1) the vulnerability of the slab-column connections; 2) lateral stiffness and drift capacity of the flat plate; and 3) implications of the observed response for earthquake resistance of similar structures of which response is not influenced by nonstructural elements. Measured drifts at the three levels of loading were estimated to within ±15% using four types of linear analyses, all based on simple estimates of stiffness reduction. Results of the investigation indicate similar structures could survive strong ground motions with peak ground velocities reaching 600 mm/s (24 in./s). [ABSTRACT FROM AUTHOR]

• The flow field structure and heat flux distribution around an isolated cylinder and tandem cylinders at different angles of attack (AoA) and inflow conditions are investigated in a Mach 6 low-noise wind tunnel. • Downstream of the recirculation region, the heat flux distribution of the isolated cylinder model forms a parallel stripe structure, while in the tandem cylinder model, it resembles a "Λ-shaped" distribution. • With the decrease in AoA , the "Λ-shaped" heat flux structure in the wake of the downstream tandem cylinders gradually disappears, and the stripe structure near the second cylinder is in a "shuttle-shaped" distribution. • With the increase in the spacing between the two tandem cylinders, the spanwise width of the "shuttle-shaped" distribution increases. • The low-heat flux area behind the second cylinder initially increases with an increase in the spacing, but when the spacing is too large, a high-heat flux stripe begins to appear in the centre of the low-heat flux region. • Placing a third cylinder on the wake centreline of the tandem cylinder has a slight impact on the flow, but its effect is enhanced when the third cylinder is located outside the recirculation region of the tandem cylinder. The flow field structure and heat flux distribution around an isolated cylinder and tandem cylinders on a flat plate at different angles of attack (AoA) and inflow conditions are investigated in a Mach 6 low-noise wind tunnel, using nano-tracer-based planar laser scattering (NPLS) techniques and the temperature sensitive paint (TSP) technique. The results reveal that, first, at AoA = 10°, the downstream cylinder will cause a horseshoe vortex formed by the upstream cylinder, which originally propagates parallel to the downstream, to expand to both sides. Subsequently, when the number of cylinders increases, the spanwise width of the affected area is increased further. In addition, a low-heat flux region caused by the recirculation region appears behind the cylinder; downstream of the low-heat flux region, the heat flux distribution of the isolated cylinder model forms a parallel stripe structure, while in the tandem cylinder model, it resembles a "Λ-shaped" distribution. A second key finding is that, with the decrease in AoA , the region of influence of the cylinder decreases. Moreover, the "Λ-shaped" heat flux structure in the wake of the downstream tandem cylinders gradually disappears, and the stripe structure near the second cylinder is in a "shuttle-shaped" distribution. Notably, with the increase in the spacing between the two tandem cylinders, the spanwise width of the "shuttle-shaped" distribution increases. The low-heat flux area behind the second cylinder initially increases with an increase in the spacing, but when the spacing is too large, a high-heat flux stripe begins to appear in the centre of the low-heat flux region. In addition, placing a third cylinder on the wake centreline of the tandem cylinder has a slight impact on the flow, but its effect is enhanced when the third cylinder is located outside the recirculation region of the tandem cylinder. [ABSTRACT FROM AUTHOR]

A numerical simulation is carried out to study flow-induced vibration of an elliptical cylinder equipped with a wake-mounted flat plate in a laminar flow regime at Re = 100. The objects are constrained to vibrate independently in the cross-flow direction. The Vortex-induced vibration of an upstream cylinder with four different aspect ratios (AR = 0.25, 0.5, 0.75, 1) is investigated in the presence of a plate mounted in different horizontal spacing of G = 0.5–3. Simulations are performed for a fixed mass ratio of 10 and negligible damping ratio across a range of reduced velocities (U r = 2–12). The results demonstrate that the presence of the flat plate can amplify the vibration amplitude of the cylinder by altering the shear layers' structure, particularly at short horizontal distances. Moreover, the phase difference of the objects shows a correlation with both the horizontal distance and the AR. Furthermore, the presence of the plate results in broader lock-in regimes across all aspect ratios by delaying its end to larger reduced velocities. While reducing the AR leads to a higher maximum vibration amplitude of the cylinder, it results to a considerably lower amplitude for the plate due to different wake structures and reduced interaction between the shear layers and the flat plate. • FIV of an elliptical cylinder with a wake-mounted flat plate is studied for different aspect ratios and horizontal spacing. • While lowering the gap amplifies the cylinder's vibration amplitude in all ARs; it is limited to AR = 0.25, 1 for the plate. • Vibration phase difference is correlated with the AR and horizontal spacing simultaneously. • Change in the shear layers structure results in higher vibration amplitude and a broader lock-in regime. • A larger maximum vibration amplitude for the cylinder and a lower one for the plate is found by reducing the AR. [ABSTRACT FROM AUTHOR]

The present study intends to find the optimal configurations of Dielectric-Barrier-Discharge (DBD) plasma actuators to augment the thermo-hydraulic performance in air flow over a flat plate at low Reynolds numbers. A range of parametric studies are conducted to determine the impact of the major contributing variables; Reynolds number, voltage frequency, and the applied voltage of the DBD actuator, on the heat transfer. This study reports that in the presence of plasma actuation, the factor of enhancement ( N u m / N u m 0 ) achieves about 3.76. Results show that reducing the Reynolds number and raising the frequency and applied voltage of the DBD actuator improve the factor of enhancement. Furthermore, the plasma system thermal efficiency (PSTE) to achieve the optimized electric power consumption and heat transfer augmentation is introduced as the rate of increase of enhancement factor to the rate of increase of consumed electric power. The frequency and applied voltage for the DBD actuator are used as the design variables to find the optimum configurations. Optimum electric power consumption and configurations of DBD plasma actuator based on Reynolds number are determined. Results also show that V app = 10.5 kV and f = 5 kHz conditions for DBD plasma actuator is much beneficial than the other configurations in the presence of low Reynolds number external flow. This study's findings will benefit designers in developing high-performance heat transfer. • DBD actuators for forced heat transfer enhancement is numerically investigated. • Optimum configuration of DBD was found to be a decreasing electric power consumption. • Utilizing a DBD actuator results in 276% heat transfer enhancement. • The enhancement factor (η) increases by reducing the Reynolds number. [ABSTRACT FROM AUTHOR]

The present work is a numerical study of thermal performance of modified flat plate solar water collectors. Numerical simulations have been done by solving the governing equations (Continuity, Momentum and Energy) equations in the laminar regime , three dimensions by using the FLUENT software version (14.5). The effect of flow on temperature distribution of flat plate water collectors by inserting (twist strip with twist ratio (3), helical spring surrounding the solid shaft) inside riser pipes is numerically simulated and compared with solar collector without inserting device inside its riser pipes at flow rates of (100)ℓ/h . The numerical simulation results show that the flat plate water, solar collectors with the inserted, twist strip and helical spring that’s surround the solid shaft were higher enhancement of heat transfer than without inserted devices. The useful energy in case of twist strip is (10%) higher than the case of flat plate solar collector without enhancement device. Also, the case of helical spring is increased (6.8 %) than the twist strip, and (16.2%) than collector without enhancement device for the same mass flow rate.

This study presents an experimental investigation on one type of embedded shearhead called ( collar head reinforcement) as shear reinforcement for tow type of reinforced concrete flat plate with presence of opening on punching shear strength. This type of shearhead is one of the structural solution that are used to increase the shear strength of flat slab . In the present research , ten specimens are tested with dimensions (1000x1000x75 mm) which are divided into two groups; the first group is a normal strength concrete with a compressive strength 30MPa; the second group is modified reactive powder concrete with a compressive strength 90MPa. Each group consists of five slabs. By using collar shearhead around the column sides and extended to the opening NSC4, the cracking load can be increased to 100% solid flat slab without collar head. For serviceability of flat plate with opening, the deflection and crack width can be reduced by using collar head around the column sides extended to the opening. The reduction can be continued by increasing the compressive strength of the concrete.