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The ceramics sector is crucial to the global economy. This research is devoted to studying the drying process of ceramic parts with arbitrary shapes based on Fick's second law of diffusion and energy conservation. Herein, the mathematical procedure to obtain the exact solutions of the model equations using the Galerkin-based integral method is provided. In the mathematical modeling are considered constant properties and equilibrium conditions at the surface of the material. Emphasis is given to clay ceramic flat plate. Analytical results of the average moisture content, local temperature, and moisture content and temperature fields within the ceramic parts are presented, followed by an in-depth discussion. [ABSTRACT FROM AUTHOR]

Compared to conventional reinforced concrete (RC) flat-plate systems, post-tensioned (PT) flat-plate systems lack experimental studies on shear strength, and there are no studies that have been analyzed and collected with clear criteria (for example, calculation of effective depth, unbalanced moment, and measured shear strength) about experiments conducted so far. As a result, the current ACI 318-19, Section 22.6.5, for prestressed members has many restrictions based on the lack of experimental data on the nominal shear-strength equation. In this study, to reevaluate the nominal shear strength of the PT flat-plate system more reasonably and provide a reference for future studies, a total of 120 experimental data on the shear strength of the PT flat-plate system without shear reinforcement that have been conducted so far were recalculated and recompiled with clear criteria (the experimental data consists of 74 interior connections, 41 edge connections, and five corner connections). In addition, the factors affecting the shear strength and the validity of restrictions in the nominal shear-strength equation of ACI 318-19 were analyzed. The factors affecting the shear strength include: 1) method of loading; 2) presence of nonprestressed reinforcement; and 3) reinforcement ratio along the lateral load direction. The restrictions in the nominal shear-strength equation of ACI 318-19 include: 1) fc' = 4900 psi (34 MPa); 2) fpc = 125 psi (0.9 MPa) (in each direction); 3) fpc = 500 psi (3.5 MPa) (average in the two directions); and 4) it is applicable only for interior connections. [ABSTRACT FROM AUTHOR]

The significance of hybrid nanofluid flow over a flat plate lies in its ability to enhance heat transfer, improve energy efficiency, enable temperature control, and provide surface protection. For instance, hybrid nanofluids can provide a protective coating on the surface of a flat plate due to the presence of nanoparticles. This coating can offer improved corrosion resistance, erosion resistance, and anti-fouling properties. Consequently, it can extend the lifespan of the flat plate and reduce maintenance requirements. In this study, we examined how several characteristics, such as variable viscosity, chemical reaction, thermal radiation and shape factor of nanoparticles, affect the flow of a hybrid nanofluid (H 2 O + MWCNT + CuO) through a flat plate. The equations required to represent the problem have been turned into a system of nonlinear ordinary differential equations, and this system has been unraveled by means of the bvp4c solver. Outcomes are provided for three instances related to shape factor i.e. Platelet, Cylinder and Spherical. Using Multiple Linear Regression (MLR), we investigated how physical parameters of concern together with friction factor, are affected by a variety of parameters. It is remarked that the fluid's velocity lessens as the variable viscosity parameter enhances. It is discovered that the temperature profile increases with the rise in exponential heat source parameter (Q e). It is discovered that when 0. 1 ≤ Q e ≤ 2. 5 , the Nusselt number declines by 0.03588 (Platelet shape), 0.03562 (Cylinder shape), and 0.03489 (Spherical shape). It has been noted that magnetic field parameter (Mg) reduces the coefficient of skin friction. At 0 ≤ Mg ≤ 3 , the skin friction coefficient is seen to drop at a rate of 1.15018 (Platelet shape), 1.14871 (Cylinder shape), and 1.14476 (Spherical shape). There is an enhancement in the Sherwood number with the rise in Schmidt number (St) and chemical reaction parameter (Cr). At 0. 1 ≤ Cr ≤ 1. 3 , the Sherwood number is seen to rise at a rate of 0.248303 (Platelet shape), 0.248344 (Cylinder shape), and 0.248447 (Spherical shape). Furthermore, it is detected that the fluid's temperature rises as the thermal radiation parameter enhances and the entropy generation increases as the variable viscosity parameter increases. [ABSTRACT FROM AUTHOR]

Superhydrophobic surfaces have gained significant attention as a promising approach for drag reduction of submerged objects. Accurate evaluation and prediction of drag reduction induced by these surfaces require expensive experimental measurements, numerical simulations, or the development of reliable models and correlations. In this paper, a model is proposed for calculating the skin friction coefficient and drag reduction of superhydrophobic flat surfaces. Utilizing previous data on the skin friction coefficient of flat surfaces under noslip boundary conditions, a model is developed to estimate the skin friction reduction and skin friction coefficient of these surfaces after applying superhydrophobic coatings. The validity of the model is verified by comparing its results with those of computational fluid dynamics (CFD) simulations of flow over a flat plate at different velocities. The results of the model and simulations indicate that for inlet velocities of 1, 5, and 25 m/s and a slip length of 50 μm, drag reductions of 15%, 41%, and 77%, respectively, are expected. Additionally, the skin friction reduction increases with increasing flow Reynolds number. The developed model is validated for flat surfaces and its ability to accurately estimate the skin friction coefficient and drag force of these surfaces is thoroughly examined. However, further investigations are required to assess the model's validity for curved surfaces and variable slip lengths. [ABSTRACT FROM AUTHOR]

AbstractUnderstanding and controlling the shape factors of nanoparticles in fluid flow problems is crucial for optimizing heat transfer, fluid dynamics, and various applications such as nanofluids, drug delivery systems, catalysis, and nanocomposites. By tailoring the shape of nanoparticles, researchers can manipulate their behavior, dispersion, and interaction with the fluid, thereby optimizing the desired outcomes in various fluid flow problems. The meticulous investigation uncovers the integration of entropy analysis in the investigation of the flow of convective magnetohydrodynamic hybrid nanofluid via a permeable flat surface, by considering the effects of Dufour, viscous dissipation, Soret, and thermal radiation. The governing equations are converted into a set of nonlinear ordinary differential equations using appropriate similarity transformations and then solved using the bvp4c solver, a MATLAB in-built function. We display the outcomes for three different shape factors: platelet, cylinder, and brick. The skin friction coefficient increases at a rate of 1.5089 for the brick shape, 1.5163 for the cylindrical shape, and 1.5212 for the platelet shape when the mixed convection parameter lies between 1 and 5. In this regard, it is important to point out that there is a direct connection between the increase in temperature transmission rate and a decline in the Dufour number (Du). It has been found that when 1≤Du≤2.4, the Nusselt number decreases by 0.4786, 0.4618, and 0.4512 for brick, cylinder, and platelet shapes, respectively. A decline in the Sherwood number is noticed with an upsurge in the Soret number (Sr). There is a noticeable increase of 0.0442 in the Sherwood number for brick shape, 0.0438 for cylinder form, and 0.0435 for platelet form when 1≤Du≤2.4. Furthermore, we have detected that an increase in the radiation parameter amplifies both the Bejan number and the profiles of entropy formation. [ABSTRACT FROM AUTHOR]

Rocket nozzles are often cooled by passing liquid propellants through channels in the nozzle walls. Estimating heat transfer to the wall from the hot gases in the nozzle is essential in deciding on the coolant flow requirements. The present work examines the computational estimation of convection heat transfer to the nozzle walls for compressible turbulent flows. Computations were performed using the rhoPimpleFoam solver in OpenFOAM® with two different turbulence models. We simulate the supersonic flow over a flat plate and validate the heat flux calculation method and turbulence model characteristics. We compare two methods of calculating convection heat transfer in the context of the nozzle flow case presented by Back & Massier. We find that the realizablek-e turbulence model works well in estimating the heat transfer coefficient. [ABSTRACT FROM AUTHOR]

In tall core-wall buildings with concrete unbonded post-tensioned flat-plate gravity framing, modeling the behavior of the slab-wallcolumn framing under earthquake loading can be crucial to determining structural response quantities for the design of the flat-plate framing. The outrigger action of the gravity system also affects the overall dynamic properties of the building and may affect wall moment and shear demands. The outrigger effect can be modeled using a slab-beam model, which uses linear-elastic frame elements with concentrated nonlinear hinges at each end. In this study, the slab-beam model is calibrated using results from a slab-wallcolumn laboratory test. Recommendations suitable for designoffice practice are presented. [ABSTRACT FROM AUTHOR]

The significance of non-Newtonian fluids is preferred for nanomaterials due to industrial demands. Consequently, this research examines the influence of magnetic fields and power law variation on nanofluids with heat transfer and heat source effects on a movable flat stretching surface assessing the nanoparticles effectiveness. Using numerical simulations via Runge–Kutta method, local similarity is used to convert partial differential equations into ordinary differential equations transformations to solve numerically and engage the local non-similarity method (LNS). The Mathematica package is used to calculate different parameters obtained in the solutions. The velocity and temperature are affected by different nanoparticles and parameters, and these effects are depicted graphically. The results obtained are compared to previous studies to confirm the inference. The output of this analysis shows that increasing the volume fraction of copper nanoparticles has a significant effect on thermal and momentum dispersion, while silver nanoparticles exhibited the maximum thermal conductivity, which is a substantial and obvious discovery regarding the increase in heat source. Furthermore, an increase in the volume fraction leads to a decrease in both the skin friction coefficient and Nusselt number. These findings have important implications for creating more efficient cooling systems for electronics and other industrial applications. [ABSTRACT FROM AUTHOR]

Anomalous heat transfer enhancement in turbulent separated air flow over a long groove of moderate depth made in a plate inclined at an angle of 45° to the freestream is revealed both experimentally and numerically. The region under investigation includes a rectangle heated to 100°C by saturated water vapor. The Reynolds number varied from 103 to 3 × 104. Using the gradient heatmetry the twofold increase, as compared with the case of a flat plate, of the heat transfer coefficient on the groove bottom is established at the Reynolds number Re = 3 × 104. The relative Nusselt number in different regions of the groove is determined both in the physical experiment and in the RANS calculations with the application of multiblock computational technologies and the SST model in the VP2/3 software package. The results are in good agreement in the turbulent flow regime at Re = (5, 10, and 30) × 103. [ABSTRACT FROM AUTHOR]

This research delves into Maxwell fluid flow's intricate fluid dynamics, as well as heat-mass transfer features over a porous horizontal plate. The investigation encompasses magnetohydrodynamics, heat generation, radiation, chemical reactions, and the influence of activation energy. Furthermore, the study integrates slip conditions for temperature, velocity, and concentration gradients at the interface between the fluid and solid surfaces. After formulating the governing equation with the abovementioned parameters, the partial differential equations are changed into ordinary ones through a similarity revolution. The results of the bvp4c solver in MATLAB provide significant insights into how various physical parameters interact and influence the flow dynamics and heat-mass transfer characteristics. This research's primary aim and objective is to comprehensively compare plots generated for different parameters under both no-slip and slip conditions by considering fixed values as Q = 0-0.3, Sc = 1–4, Ec = 0–1, Pr = 1–4, σ = 0–2, E = 0.1-0.7, λ = 0–2. The primary discoveries of this study indicate that with an increase in the power index, there is a decline in the concentration profile. In contrast, an increase in the activation energy leads to an elevation in this profile. An important revelation from this research is the significant decrease observed in the concentration profile as the activation energy parameter is raised.

Cryogenic heat exchangers are important for vaporizing liquefied natural gas or liquefied hydrogen and utilizing their cryogenic energy, but frost formation causes severe problems that deteriorate performance. Frost formation on a cryogenic surface is characterized by simultaneous mist formation. However, the detailed frosting mechanisms, especially the interaction between frost and mist formation under forced convection, have not been revealed. In this study, we experimentally observed the frost and mist formation on a flat plate under forced convection over a wide range of cooling surface temperatures (Tw), from general-low to cryogenic. The frost and mist layer height was quantitatively measured with a white LED and a laser sheet light source in addition to the frosting amount. As a result, the frosting style was classified into three groups depending on the cooling surface temperature under the air temperature of 27°C, air humidity of 12 g/m3, and air velocity of 2.0 m/s. When Tw ≥ −75°C, the mist was hardly generated, and needle-shape or dendric frost formed by desublimation almost uniformly on the entire plate surface. On the other hand, frost is not uniformly formed in the flow direction at Tw ≤ −100°C. Frost hill is formed by desublimation at the leading edge and protrudes higher as the cooling surface temperature is lower. The high frost hill leads to the flow detachment behind it and the persistent mist generation, affecting the frost growth on the rear. Thus, under forced convection, the frost hill shape and the flow detachment behind it are important factors determining the frosting style.

The ceramics sector is crucial to the global economy. This research is devoted to studying the drying process of ceramic parts with arbitrary shapes based on Fick’s second law of diffusion and energy conservation. Herein, the mathematical procedure to obtain the exact solutions of the model equations using the Galerkin-based integral method is provided. In the mathematical modeling are considered constant properties and equilibrium conditions at the surface of the material. Emphasis is given to clay ceramic flat plate. Analytical results of the average moisture content, local temperature, and moisture content and temperature fields within the ceramic parts are presented, followed by an in-depth discussion.

In this article, we have discussed two-dimensional steady, incompressible, and laminar hydromagnetic flow along with the transfer of heat above a plane plate that contains water and ethylene glycol-based nanofluids with multi- and single-wall CNTs. The velocity slip boundary condition is included in this research article to evaluate the nature of flow. The plate surface is subjected to variable wall temperature. The transfer of heat has been contemplated in the company of suspended CNTs above a flat plate. Navier–Stokes and the concept of the Prandtl boundary layer have been used to determine the governing equations of heat transfer and flow. Since the attained governing equations representing energy and flow are nonlinear PDEs, they are altered into nonlinear ODEs accompanied by analogous boundary limitations by applying some appropriate similarity transformations. Hence the "RK45" function is used to solve them numerically. The influence of governing parameters on the dimensionless flow and heat transfer profiles are studied and discussed thorough graphical plots. [ABSTRACT FROM AUTHOR]

In this work, an experimental investigation of the hydrodynamic resistance of a flat plate painted with newly developed marine antifouling paints of polyurethane (PU) and silicone (Si) formulations was performed. In total, six different paint systems of Si, PU, and acrylic formulations were applied, both experimental and commercial. The total resistance of each painted condition of the plate was measured through towing tank tests for the range of 0.75-2.5 m/sec, with a step of 0.25 m/sec. The Si and PU formulations exhibited similar hydrodynamic behavior, fluctuating around the smooth condition, whereas the acrylic system exhibited the highest resistance increase of all. The roughness function calculation was based on Ra and the correlation with the Colebrook roughness function was generally limited for most systems. Extrapolation to ship scale revealed that no significant drag differences are expected in the as-painted condition among the different paint system types. [ABSTRACT FROM AUTHOR]

The present study investigates experimentally the influence of a movable air jet impingement on the characteristics of heat transfer over a flat plate. The experiments are conducted with a nozzle translation velocity ( V n ) of 200 mm min−1, a Reynolds number (Re) of 24,000, and a nozzle-to-plate distance ratio (H/D) of 1, 3, 5, and 7. The characteristics of heat transfer on a flat surface due to the use of a movable air nozzle are compared with those of a fixed one using an IR camera. The local Nusselt number (Nu), average Nusselt number ( Nu ¯ ), heat transfer uniformity index (HTU), and heat transfer uniformity (U) are investigated. The results demonstrate that the movable nozzle is more effective than the fixed one for reducing the temperature variation over the heating surface, leading to more heat transfer uniformity. The maximum values of both the Nu and Nu ¯ are obtained at a H/D of 1. The U that is improved for the movable nozzle when compared to the fixed nozzle is significantly influenced by the H/D. The maximum values of U are 85 and 72% at a H/D of 7 for the movable and fixed nozzles, respectively. The movable nozzle improves the uniformity of heat transfer more than the fixed one by 75, 42, 39, and 43% at a H/D of 1, 3, 5, and 7, respectively. Moreover, a comparison between the results of the Nu ¯ of the present work and those of previous studies is conducted. [ABSTRACT FROM AUTHOR]

The rapid increase in computing power has facilitated the use of computational fluid dynamics (CFD) as an attractive tool for simulating solar systems. As a result, researchers have conducted numerous experimental and numerical studies on solar technologies, with an increasing emphasis on the utilization of CFD for simulation purposes. Hence, this article is intended to be the first of a two-part assessment of recent improvements in the use of ANSYS-Fluent CFD simulation in solar systems. In this part, the article aims to provide a comprehensive overview of CFD simulations, using ANSYS-Fluent, for different solar systems without concentrators, including solar thermal systems, hybrid photovoltaic/thermal (PV/T) systems, and photovoltaic/phase change material (PV/PCM) systems, while the concentrating solar systems are covered in the second part. Further, this review study includes informative data about the simulations, including the considered assumptions, models, and solution methods that were used with different cooling fluids, PCM materials, absorber designs, and innovative system designs. The present assessment also highlights the results and some remarks that show different important additional information such as the applied radiation and melting/solidification models. Besides, validation techniques and errors between the experimental work and simulations are introduced. In general, the ANSYS-Fluent CFD results were validated and it was possible to optimize many design parameters with minimal effort and expense. Recent research indicated that nanofluids could be a better alternative to conventional fluids to improve the thermal functionality of flat plate and hybrid PV/T systems. Effective cooling mechanisms could reduce PV panel temperature by 15–20%. Besides, integrating PCM with PV systems could enhance efficiency by 33–46% on summer days. Incorporating different nanomaterials and using fined PV/PCM configurations, the PV/PCM system demonstrated improved cost-effectiveness, while a foam layer outside the PCM could extend PV thermal management time by 55%. Many other conclusions about the commonly used physical models, solution methods, and assumptions dealing with different systems are highlighted inside. The article also identifies additional research proposals and challenges that must be addressed to advance the study of this topic. [ABSTRACT FROM AUTHOR]

The Flat Plate is a common component of solar photothermal experiment and an important teaching tool in the new energy teaching experiment. Aiming at the problem of low heat transfer efficiency and poor teaching effect of traditional roll-bond flat plate, this paper conducts a numerical simulation study on the flow and heat transfer characteristics in the ”Y” -shaped channel unit. The four parameters of width, length, runner parting angle and runner width are used as control variables to optimize the heat transfer structure of the runner. Taking the ”Y” -shaped channel unit as the research object, the finite element model of conjugate heat transfer was established by using Fluent. Through numerical simulation analysis, it is concluded that in the defined length and width interval, the thermal efficiency increases first and then decreases with the increase of the length of the heat transfer unit, and the pressure drop coefficient has a negative correlation with the length and width of the unit. The runner width has a positive correlation with the thermal efficiency and a negative correlation with the pressure drop coefficient. Then, according to the Box-Behnken principle, a response surface test for heat transfer optimization was designed, an optimization model with thermal efficiency and pressure drop coefficient as the response indicators was established, and the optimal element design scheme was determined. The optimization results show that when the subunit length of the heat transfer runner is 40 mm, the width is 35 mm, the parting angle is 60°, and the runner width is 11 mm, the thermal efficiency of the ”Y”-shaped runner is 0.782, and the pressure drop coefficient is 0.121. Finally, a direct-expansion solar auxiliary heating system is built to test the scheme. The experimental results show that the collector using the ”Y”-shaped channel shows better solar energy utilization, which increases the COP of the system by 15.2%. This study provides a reference for the design and optimization of other types of flow channels to improve the heat transfer efficiency of the roll-bond flat plate. Through optimization, the system has innovated in the experimental mode, effectively made up for the shortcomings in the training of new energy professionals, and enriched and developed the experimental theory system and teaching methods of higher education of energy and power majors.

Abstract The objective of this study is to conduct an experiment that considers the influence of vertical oscillations on the heat transfer coefficient of free convection in an aluminum flat plate component measuring 3 × 100 × 300 mm. The plate is subject to a steady-state heat transfer; whereby it experiences a sustained heat flux ranging from (250–1500) W/m2. The orientation of the flat plate can be either horizontal or inclined at particular angles, specifically at 0°, 30°, 45°, 60°, and 90°. The experimental tests conducted were characterized by an expanded frequency spectrum ranging from 2 to 16 Hz, a variable amplitude range spanning from 1.63 to 7.16 mm, and a range of Rayleigh number values upon activation of the system, with minimum and maximum thresholds of 138.991 and 487.275, respectively. The impact of vibration frequency upon both the amplitude and velocity of vibrations for a heat flow of 250 W/m2, situated at an angle of θ = 0°, was examined. The impact of the Reynolds number upon the total vibrational heat transfer coefficient, as well as the total Nusselt number, was investigated with and without the presence of angle vibration θ = 0°, across diverse degrees of heat flux. This study investigates the impact of the Rayleigh number on the overall Nusselt number under varying conditions of thermal flux, with and without the application of vibration at angles of θ = 30°, 45°, 60°, and 90°. The findings of this analysis demonstrate that there exists a discernible correlation between the incremental amplitude of vibration and the coefficient of heat transfer, manifesting as a negative slope within the range of 0° to 60°. Such correlation reaches its optimal magnitude of 13.2894% under the condition of flat vibration mode, whereas the coefficient of heat transfer declines progressively as vertical vibration is augmented, culminating in a maximum decline of 7.6475%. The present study reports a decrease in the overall vibrational heat transfer coefficient with increasing vibrational Reynolds number. The total Nusselt number was found to increase with or without vibration as the Rayleigh number increased.

Undesirable flapping motion of discs can cause the failure of swing check valves in nuclear passive safety systems. Time-resolved particle image velocimetry (PIV) was employed to investigate the flow characteristics around a free-to-rotate plate and the motion response, with the Reynolds numbers, based on the hydraulic diameter of the channel, from 1.32 × 104 to 3.95 × 104. Appreciable flapping motion (±3.52°) appeared at the Reynolds number of 2.6 × 104 with the frequency of 5.08 Hz. In the low-Reynolds-number case, the plate showed negligible flapping. In the high-Reynolds-number case, the deflection angle increased with reduced flapping amplitude. The torque from the fluid determined the flapping amplitude. In the low-Reynolds-number case, Karman vortices were absent. With increasing Reynolds numbers, Karman vortices developed behind the plate with larger deflection angles. Strong interaction between the wake flow from the leading and trailing edge of the plate was observed. Based on power spectrum density (PSD) analysis, the vortex shedding frequency coincided with the flapping frequency, and the amplitude was positively correlated to the strength of the vortices. Proper orthogonal decomposition (POD) modes evince that, in the case of appreciable motion, coherent structures exhibited a larger spatial scale, enhancing the magnitude of the external torque on the plate.

Abstract The flow past two parallel flat plates is undoubtedly one of the most classic problems in fluid mechanics, as the aerodynamic and heat transfer performance can be significantly affected by the geometry of the flat plate. In this work, using the open-source package OpenFOAM, we first performed a numerical investigation on the fluid flow and heat transfer past two parallel flat plates with different aspect ratios (AR) and inclined angles (α). The representative vortex structures and instantaneous flow patterns were presented and analyzed. We then discussed the local force characteristics and heat transfer rate on the plate walls, as well as the velocity and temperature distributions near the wake. The global flow unsteadiness and heat transfer characteristics were obtained. The numerical results revealed that larger AR and α enhanced the flow unsteadiness and increased the fluid force. The global heat transfer performance increased with increasing α, but first decreased and then increased with increasing AR. The objective of this work was to further achieve a more effective flat plate application and to provide theoretical support for its improvement. [ABSTRACT FROM AUTHOR]

New tests of software packages and turbulence models for validating the problems of highly intense vortex flows past structured energy-effective surfaces are presented. The idea of the testing is based on the discovery of anomalous intensification of separation flows and heat transfer in inclined grooves in plates and channel walls. At the expense of extraordinary pressure differences in the grooves, which are confirmed in experiments, swirl flows with high velocities of return and secondary currents are formed. These velocities are comparable with that of the freestream. Moreover, high-gradient zones with friction and heat removal many times higher (by a factor of from 1.5–2 to 7–9) than the friction and heat removal on a flat wall are formed. By way of illustration, we present the results of testing the VP2/3 software package developed on the basis of original muliblock computational technologies and using intersecting different-in-scale grids. The comparison of the numerical predictions with M.A. Zubin's experiments confirmed the high static-pressure differences between the deceleration zone on the windward slope of an inclined groove and the negative pressure region at the place of tornado-like flow generation on the spherical entry segment and asserted the applicability of the RANS approach in predicting the characteristics of highly-intense swirled flows. [ABSTRACT FROM AUTHOR]

Results of experimental studies are applied to compare the spatiotemporal amplitude distributions of controlled fluctuations in a linear and a weakly nonlinear phase of the development of a wave train in a homogeneous and an inhomogeneous boundary layer on a flat plate at a Mach number M = 2. (The flow is inhomogeneous due to a longitudinal steady perturbation generated by a pair of weak shock waves. Controlled perturbations are generated locally from the surface at a fixed power of a high-frequency glow discharge inside the model.) It is revealed that the inhomogeneity of the flow changes the mechanism of interaction of subharmonic perturbations. It is shown that the spatial synchronism of fluctuations of subharmonic frequency is violated in the center of the wave train. [ABSTRACT FROM AUTHOR]

This study undertakes an experimental and computational evaluation of a dual-flow solar air heater (SAH) equipped with three distinct types of absorber plates: flat, trapezoidal, and U-corrugated. Experiments were conducted under actual outdoor weather conditions in Baghdad, Iraq (33.31°N, 44.36°E) during varying days in April and May 2022. The collector, oriented south (surface azimuth angle = zero due south) and tilted at an angle of 30° from the horizontal, was scrutinized under four different airflow rates: 0.0011, 0.0023, 0.0036, and 0.0046 kg/s. Computational simulations of the four absorber plates were performed using ANSYS Fluent software to ascertain and validate thermal efficiencies and performance characteristics. Findings indicate that at an airflow rate of 0.0046 kg/s, the thermal efficiencies of the SAHs with flat, U-corrugated, and trapezoidal plates were 43%, 51%, and 54% respectively. Additionally, a shift from parallel to anti-parallel airflow direction resulted in an increased thermal efficiency from 51% to 56%. It was determined that the optimal configuration was achieved with the U-corrugated plate in an anti-parallel airflow. The average efficiencies at the maximum airflow rate of 0.0046 kg/s were reported as 42.80% for the flat plate, 51.33% for the U-corrugated plate with parallel airflow, 54.38% for the trapezoidal plate with anti-parallel airflow, and 55.53% for the Ucorrugated plate with anti-parallel airflow. Finally, a favorable alignment between the experimental and simulated results was observed, with an average discrepancy of 5.7% in thermal efficiency. [ABSTRACT FROM AUTHOR]

The classical problem of boundary layer problem over a flat plate is considered by employing a local non-similarity approach of the momentum and energy equations provided with the non-constant heat flux condition. Several similarity solutions are seen in literature that have not captured the complete solutions of the physical phenomenon. This paper demonstrates that the solution obtained using the local non-similar technique is preferred to the solution obtained using the similarity transformation technique, especially if the non-constant temperature (surface) with the hot fluid is considered. By exploiting the local non-similarity technique, the mathematical model presented in two-variable differential system is transformed into a coupled non-dimensional ODEs system of equations that is evaluated at a certain streamwise value using a Runge–Kutta–Fehlberg fourth-fifth numerical method. Upon validation of the method, the profile distributions of respective boundary layers with respect to the Biot and temperature ratio parameters are analysed and discussed. Table and graphs are used to illustrate the improvements in the local non-similarity solution and the necessity of adopting this method for non-similar problems. For Biot parameter a ∈ [ 0.05 , 100 ] , the thermal boundary layer is supported positively and ξ ∈ [ 0.0 , 2.0 ] downsizes the thermal boundary layer. [ABSTRACT FROM AUTHOR]

Modelling of transition from the laminar to turbulent flow became a hot topic due to recent developments in renewable energy, UAV technologies and similar aerospace applications. The transition from laminar flow to turbulence is challenging to model in CFD analysis. The drag is overestimated if the transition is neglected in CFD solutions by assuming the flow is fully turbulent. This results in missing the fundamental characteristics of the flow and inaccurate predictions of the flow field. The most popular transition models are Menter's models applied to the SST turbulence model and the Baş-Çakmakçıoğlu (BC) transition model applied to the Spalart-Almaras model. We have focused on Menter's simpler but more popular γ model and Baş Çakmakçıoğlu models. The γ model relies on the local turbulence intensity, which makes applying the model challenging in external flows. This difficulty stems from the complex relationship between turbulence decay and transition onset. BC transition model utilizes the free stream turbulence intensity. Both models are verified using the Klebanoff and ERCOFTAC flat plate cases and several 2D external flow cases. Skin friction coefficient results are compared to experimental data. Results show that both models predict transition very similarly. BC model is computationally cheaper and easier to implement than the γ model. Also, γ model suffers from boundary conditions ambiguity. [ABSTRACT FROM AUTHOR]

e study the distribution of temperatures for the radiative MHD Ekman layer on a porous flat plate by including Joule's dissipation function for the following cases: (i) A steady temperature is preserved on the plate. (ii) The plate is insulated. We obtain exact solutions in the two instances of sucking and blowing (such a solution does not exist in the event that there is no radiative heat emission present and blowing is taking place). [ABSTRACT FROM AUTHOR]

Strengthening of flat slab-column connections to resist imposed lateral drifts is often required for older reinforced concrete structures in which the flat slabs were typically designed to resist gravity load only or have been designed for less stringent requirements. The complex stress state around the columns means that strong experimental evidence is required for the repair and strengthening techniques to be adopted with confidence in practice. Although a significant amount of research has been devoted to strengthening of slab-column connections, a series of limitations still remain. A thorough literature review revealed that only relatively thin and isolated specimens have been tested under seismic-type loading and realistic strengthening scenarios. To overcome these limitations, a full-scale two-story flat slab building specimen was tested at the European Commission's Joint Research Centre – ELSA Laboratory in Ispra, Italy. This paper describes and analyzes the results obtained from the last of a series of phases, on repaired and strengthened internal and external slab-column connections using post-installed bolts. Compared with previous tests, the full-scale building specimen has a thicker slab (200 mm), realistic slab continuity conditions and the connections were strengthened after they suffered damage from gravity loading and previous lateral loading phases. The results show that post-installed bolts are efficient even under the described conditions (i.e. damaged and repaired specimens with realistic thickness), and punching shear failure was prevented in the strengthened connections. [ABSTRACT FROM AUTHOR]

The effects of a trailing-edge active controlled flap on the power output performance of an oscillating wing energy harvester were investigated by numerical analysis. The overset mesh technique was adopted, and a structured mesh was used to simulate multiple moving bodies in close proximity to a wall to improve the accuracy. Sinusoidal motion was applied to both the wings and flaps. The maximum pitch angles for the wing and flap were varied to determine the optimum operating conditions. Numerical results show that the attachment of a flap onto an oscillating wing deflects the incoming flow in flap's direction and increases the vertical momentum change, which consequently increases the pushing force and power. The wing and flap maximum pitch angles significantly affect the power output of the energy harvester. The maximum power output is obtained at maximum pitch angles of 70° and 35° for the wing and flap, respectively. The maximum power is enhanced by 11 % when the flap length is 20 % of the chord length, as compared with the optimum condition of an oscillating wing without a flap. [ABSTRACT FROM AUTHOR]

Convective heat transfer from a flat plate, which is enhanced by an oscillating blade, was numerically investigated at the present study. It was assumed that the blade is made of a rigid and thin plate and it is vertically oriented at the top of the target plate. Numerical analysis was performed using commercial software ANSYS Fluent 6.3 and the periodic oscillation of the blade was modeled by the moving mesh method. Conservation equations of mass, momentum and energy was solved in 2-D and transient form for the laminar airflow with constant physical properties. Constant temperature was considered for the plate and the details of both the flow and thermal fields were determined. The distribution of convective heat transfer coefficient was then calculated for the target plate. The effect of various parameters including the amplitude and frequency of the blade oscillation as well as the geometrical parameters was investigated on the convective heat transfer from the target plate. The results indicated that a wider area of the plate was affected by increasing the oscillation amplitude of the blade. Convective heat transfer was also enhanced over the entire target plate as the rotational Reynolds number was increased.

Thermal management for multiple heat sources has been becoming increasingly important, especially under high heat flux conditions. As a passive heat transfer device, loop heat pipes (LHP) with multiple evaporators does not consume extra energy, demonstrating a great potential in thermal management. This paper proposed a flat plate LHP with dual evaporators for the first time. Two flat plate evaporators were adopted, and both of them had their own porous wick, compensation chamber (CC) and vapor line. The condensed liquid converged, then moved along the main liquid line. The CC of two evaporators was joined by a tube, which can ensure the sharing of the returning liquid. To verify the performance of novel flat plate LHP, the start-up test was investigated under different heat load arrangements, involving only a single evaporate was applied heat load, two evaporators were applied with the equal or unequal heat load. Meanwhile, the operation stability was determined by testing the performance with the successionally variable heat load. This system has been shown to operate successfully at heating source temperature below 100 °C with heat load ranging from 10 W–10 W to 130 W–130 W (corresponding to the maximum heat flux of 13.52 W/cm2).

Computational analysis of elliptic and normal flat plate geometries, sized to wings of small fliers and in a two-dimensional plunging-pitching-flapping motion resulting in hover, is conducted to investigate circulation growth at the leading-edge vortex (LEV) and trailing-edge vortex (TEV). The models are sized to the same aspect ratio, and a Reynolds number of 225 is chosen as it is similar to that observed in small fliers in hover. Results show similar LEV growth and lift production trends for both cases but with differing energy flux mechanisms. A vorticity transport analysis is done to quantify these energy fluxes. The LEV growth and shearing is closely related to the TEV growth and shearing, and the plunging-pitching profile, while the geometry plays a role in the magnitude of vortex creation and intensity of spanwise fluxes only. [ABSTRACT FROM AUTHOR]

An experimental study of the influence of the leading-edge radius of a blunt plate on the response of boundary layer on this plate to an N-wave at Mach 2 was carried out. Three flat-plate models with different leading-edge bluntness radii, r = 0.05, 0.5, and 2.5 mm, were used in the experiments. The oncoming-flow disturbances were created using a generator provided on the sidewall of the test section of the T-325 wind tunnel of ITAM SB RAS. It is found that behind the N-wave in the oncoming flow, there forms an extended region with an increased level of flow pulsations whose spectrum contains the amplitudes increased both in low-frequency and high-frequency range of the spectrum compared to the undisturbed freestream. It was shown that, under experimental conditions, the flow non-uniformity generated by the N-wave can exert a greater influence on the flat-plate boundary layer laminar-turbulent transition with increasing leading-edge bluntness radius. [ABSTRACT FROM AUTHOR]

Heat transfer takes place in every aspect of our daily life. Many situations, such as energy conversion plants, heating devices, and cooling systems, focus on heat transfer. One of the subjects in heat transfer is the boundary layer of the laminar flow problem. Well-known exploratory algorithms are used to solve for the flow on a flat plate in this study. The algorithms used are genetic algorithm (GA), particle swarm optimization (PSO), simulated annealing (SA), ant colony optimization for continuous domains (ACOR), artificial bee colony (ABC), and firefly algorithm (FA). The three properties, the layer thickness of the laminar boundary, heat flux, and the distance of the leading edge, are optimized. Each property is determined in three conditions; minimum, maximum, and target. The results showed that PSO, SA, ABC, and FA algorithms were more suitable than GA and ACOR algorithms. It has also been determined that the processing times are long in the FA and SA algorithms. The findings show that heuristic algorithms can find global results or results close to global results in heat transfer problems.

Stoke's problems significantly impact several domains, including industrial manufacturing, geophysical flows, chemical engineering, and heat conduction. Stoke's second problem deals with the movement of a semi-infinite viscous incompressible fluid caused by an oscillating flat plate. Thus, this work examines Stoke's second problem for an unsteady hydromagnetic surface-driven flow along an infinite flat plate in the presence of thermal radiation and heat dissipation. The governing momentum and energy equations form an emerging nonlinear system of partial differential equations through dimensionless proxies. MAPLE 2022 is employed to solve the resulting system of nonlinear partial differential equations that control the flow both analytically and numerically in specific situations. The analytical solutions are displayed graphically, along with variations of skin friction and Nusselt number at the plate. It has been observed that momentum and thermal slips significantly diminished the flow characteristics to cause damping flow rate and temperature distributions. Rising the values of Magnetic and velocity slip parameters, an oscillatory motion is observed in skin friction. This is due to the periodic and wavy nature of the boundary wall. Furthermore, a rise in the Prandtl number and radiation value correspondingly boosted the wall heat gradient profiles. Finally, this study will assist industry and engineering in understanding the sensitivity of their working fluids to parameter variations and for the exact prediction of their base fluids.

In this paper, the new semi-analytical correlation for displacement thickness of laminar fluid flow along an arbitrary-angle corner formed by the intersection of two plates has been proposed because of the discrepancy in displacement thickness for strong interference corner between the present computational fluid dynamics simulation and previous analytical correlation. [ABSTRACT FROM AUTHOR]

Fuel costs and environmental pressures increase interest in improving fuel economy in the commercial vehicles. Presumably, the most economical way to improve a vehicle's fuel economy is to make it more aerodynamically efficient. In this work, the aerodynamic performance of flat plates placed upstream of and parallel to the front lower surface of a 1:25 coach model at zero and non-zero yaw angles (β≤9°) has been experimentally investigated. Comparative studies have been performed at a width-based Reynolds number Rew=104000±3000, considering the coach model without flat plate. The force measurements suggest the existence of a critical plate width at which a steep increase in time-averaged drag coefficient, , was observed. At zero yaw, a geometrical configuration consisting of a plate width seven tenth of the coach's width (w) placed 0.16w upstream of the coach model produces a time-averaged drag that is 92.9% that of the coach model without plate. It is seen that this configuration is also effective in reducing under crosswind conditions. [ABSTRACT FROM AUTHOR]

Due to the entrapment of compressible air, the process of a flat plate impact on water is complicated, which cannot be reproduced using incompressible simulations. To investigate such a slamming process, an accuracy compressible fluid–structure interaction numerical model has been proposed. The solution of this model is based on the constrained interpolation profile (CIP) method to solve the Navier–Stokes equations for the computation of fluid, and an implicit immersed boundary method (IBM) is used to calculate the fluid–structure interaction. Firstly, the present (CIP–IBM–based) model is validated against the problem of the flow past a stationary cylinder. Then it is implemented to simulate the problem of a rigid flat plate impact on water. The predicated impact pressure is compared with reference experiments and other simulations. The CIP–IBM–based model shows a better performance in dealing with sub-atmospheric pressure and reloading. From the numerical view, it is shown that the oscillation of the slamming pressure is significantly affected by the compression and expansion of the entrapped air cushion, and under the influence of the air cushion, the slamming pressure distribution along the bottom is not constant, which also varies greatly with time. [ABSTRACT FROM AUTHOR]