Rib Type Research Articles

A numerical study of the effect of different geometrical parameters on the cooling processes in electrical transformer

Proper thermal control is one of the most important aspects that should be considered when utilizing electrical transformers. This research work offers a numerical analysis of the effect of changing the shape of transformer fins on the heat exchange process. Based on the results of CFD simulations, several types of fin shapes such as rectangular, triangular and wavy are discussed to describe the improvements of heat transfer. The study examines the shape of an electrical transformer, determining the optimal distance between fins, fin shapes, transformer shape, rib type, and rib number. The results are then applied to a special case, representing the best of all variables on the transformer. The study also considers the effect of increasing the surface area of the ribs on the fins, and the number of ribs used on the fins. The temperature gradient of a coil, oil, and transformer varies depending on the distance between fins, fin shape, rib type, and number of ribs. The coil temperature is 383 K when the fins are 7 cm apart, 381 K when the fins are 5 cm apart, and 381 K when the fins are 3cm apart. The temperature gradient also varies depending on the rib type, with triangular ribs increasing the surface area for heat energy transfer and reducing the temperature value. The oil temperature gradient varies depending on the fins, ribs type, and number of ribs. The heat transfer coefficient gradient of the transformer surface varies depending on the fins, ribs type, and number of ribs. The surface heat transfer coefficient reaches 1.5 W/m2. K when the fins are l shape, 1.6 W/m2. K when the fins are c shape, 1.7 W/m2. K when the fins are z shape, 1.4 W/m2. K when the ribs are rectangular, 1.6 W/m2. K when the ribs are triangular, and 1.4 W/m2. K when the ribs are 9 ribs.

Estimation of losses caused by sidewall roughness in thin-film lithium niobate rib and strip waveguides.

Samples of dielectric optical waveguides of rib or strip type in thin-film lithium niobate (TFLN) technology are characterized with respect to their optical loss using the Fabry-Pérot method. Attributing the losses mainly to sidewall roughness, we employ a simple perturbational procedure, based on rigorously computed mode profiles of idealized channels, to estimate the attenuation for waveguides with different cross sections. A single fit parameter suffices for an adequate modelling of the effect of the waveguide geometry on the loss levels.

Auxetic fixation devices can achieve superior pullout performances compared to standard fixation concepts

Despite bone screws being the most commonly inserted implant in orthopaedic surgery, 10% of fracture fixation failure is a result of screw migration or pullout. In this study, the effect of four auxetic structures on the pullout performance of a novel unthreaded bone fastener was investigated through experiments and numerical simulations. The auxetic fasteners included the re-entrant, rotating squares, missing rib, and tetrachiral structures. Parametric CAD models were developed for each, and polymer samples manufactured using a stereolithography process. Pullout testing using bone analogue material found the rotating squares fastener to achieve superior pullout resistance 2.5 times that of the non-auxetic control sample. With a pullout to push-in force ratio of 33.7, this fastener achieved high pullout resistance with a low insertion force improving ease of installation. The Poisson’s ratio of the structure was determined using image analysis to be −1.31, similar to the missing rib and re-entrant types. The low axial stiffness of 12.1 N mm−1 for the rotating squares fastener was the reason for superior performance, allowing axial and resulting transverse strain to be initiated at relatively low load. The effect of increased diametral interference was investigated, and the re-entrant structure found to be superior with pullout resistance improved by 342%. This work provides a foundation for further development of unthreaded auxetic bone fasteners, which have the potential to replace screws for some orthopaedic applications and significantly reduce the prevalence of pullout as a failure mode.

Vertical shear capacity of steel–normal concrete-UHPC composite slabs with steel ribs in the cantilever

UHPC is utilized to enhance flexural performance of tensile zone of composite slabs, which will enable reducing slab height. The vertical shear resistance of composite slabs in the cantilever might become insufficient with the reduction of slab height. In the paper, the vertical shear performance of steel-normal concrete-UHPC composite slabs in the cantilever is investigated based on five composite slabs tests, numerical simulation, and theoretical analysis. The results indicate that UHPC layer changes the failure mode of steel concrete composite slabs. The bearing capacity and ductility of composite slabs are effectively enhanced with the application of UHPC. The addition of a 10 cm UHPC layer makes the bearing capacity of composite slabs increase by 69.97%. And the reinforcement ratio of UHPC layer and the type of steel ribs exert a significant influence on the shear resistance. Additionally, an analytical model derived from modified compression field theory can well predict vertical shear bearing capacities of composite slabs in the cantilever.

Analysis of enhanced thermal transmission mechanism with microstructures by field synergy theory

This study numerically examines the impact of oblique ribs and staggered herringbone microstructures on the heat transfer performance of microchannels. The results indicate that the Nux values of the oblique rib (Type A) and staggered herringbone (Type B) microchannels exhibit significantly higher performance compared to smooth rectangular (Type C) microchannels. The oblique ribs and staggered herringbone microstructures improve heat transfer efficiency along the flowing direction, leading to an evident increase followed by horizontal fluctuations in Nux . In contrast, the Nux of Type C without microstructures decreases significantly at the inlet and subsequently remains relatively constant. The bottom temperature Tw of Type A and B are lower than the temperature of Type C. The results of field cooperation analysis indicate that the synergistic fields of the oblique ribs microchannels primarily exist along both sidewalls, while they are present at the fluid center for the staggered herringbone microchannels. Type A exhibits a slightly stronger heat transfer effect despite having a smaller synergistic area compared to Type B.

Numerical assessment of solar air heater performance having a broken arc and broken S-shaped ribs as roughness

This research article aims to provide a detailed numerical study of the multifaceted impact of S-shaped and broken arc roughness on solar air heaters. Therefore, a strong comparison was made between the modified heaters and smooth heaters for Reynolds numbers ranging from 2 00022 000. Also, the impact of two parameters, i.e. pitch and gap was analyzed to optimize the performance of the heater. The gap varies from 0.3 mm to 0.9 mm in both types of ribs with a step size of 0.2 mm. Afterwards, the pitch distance between both types of roughness was varied from 15 mm to 25 mm in the step size of 5 mm. Notably, it has been observed that among all the considered configurations, the gap length of 0.9 mm and pitch length of 25 mm have shown significant improvements in heat transfer characteristics. The specific combination of the gap of 0.9 mm and pitch of 25 mm has demonstrated better heat transfer capabilities at the expense of an increased friction factor. Lastly, the thermal performance factor of the systems was analyzed and reported. It was reported that the pitch length of 25 mm and gap length of 0.9 mm have shown a maximum thermal performance factor value from 2.9 to 3.3, while the pitch length of 25 mm and gap length of 0.3 mm have depicted the lowest thermal performance factor value. In terms of the overall performance, i.e. the thermal performance factor, the combination with a gap of 0.9 mm and pitch of 25 mm has shown the best performance, while a gap of 0.3 mm and pitch of 25 mm has yielded the worst performance.

The axial skeleton of Tiktaalik roseae

The axial columns of the earliest limbed vertebrates show distinct patterns of regionalization as compared to early tetrapodomorphs. Included among their novel features are sacral ribs, which provide linkage between the vertebral column and pelvis, contributing to body support and propulsion by the hindlimb. Data on the axial skeletons of the closest relatives of limbed vertebrates are sparce, with key features of specimens potentially covered by matrix. Therefore, it is unclear in what sequence and under what functional context specializations in the axial skeletons of tetrapods arose. Here, we describe the axial skeleton of the elpistostegalian Tiktaalik roseae and show that transformations to the axial column for head mobility, body support, and pelvic fin buttressing evolved in finned vertebrates prior to the origin of limbs. No atlas-axis complex is observed; however, an independent basioccipital-exoccipital complex suggests increased mobility at the occipital vertebral junction. While the construction of vertebrae in Tiktaalik is similar to early tetrapodomorphs, its ribs possess a specialized sacral domain. Sacral ribs are expanded and ventrally curved, indicating likely attachment to the expanded iliac blade of the pelvis by ligamentous connection. Thus, the origin of novel rib types preceded major alterations to trunk vertebrae, and linkage between pelvic fins and axial column preceded the origin of limbs. These data reveal an unexpected combination of post-cranial skeletal characters, informing hypotheses of body posture and movement in the closest relatives of limbed vertebrates.

Experimental investigation of self-centering beam-to-column connections with different ribbed top and seat angles

This study experimentally investigated the seismic behavior of a novel self-centering beam-to-column connection with the different ribbed top and seat angles. The connections were composed of square concrete filled steel tubular (CFST) column, H-shaped steel beam, angles with or without stiffening rib, and post-tensioned (PT) high-strength steel tendons. Eight half-scale specimens were designed and tested under cyclic loading. The influences of stiffening rib type including plane rib and multi-wave rib, PT tendon distance, and with or without PT tendons upon the performance of the connection were evaluated experimentally. The results show that the connections installed PT tendons exhibited the double linear hysteretic feature with a slight narrow hysteretic loop due to the friction of the components, the connections assembled the angles or ribbed angles took on the fuller and more stable hysteretic loop, and the connections installed the PT tendons and ribbed angles exhibited the double-flag shaped hysteretic curve. The employment of plane or multi-wave ribbed angles significantly increased the initial rotational stiffness and ultimate moment. For the connection combined the PT tendons and ribbed angles, the average residual rotation angle ratio and the maximum equivalent viscous damping ratio reached about 0.095 and 0.07 at the drift ratio of 2%, respectively. The distance of PT tendons did not affect the hysteretic behavior of the connection. The PT tendons could provide the excellent self-centering behavior of the connection.

A comparative study of internal heat transfer enhancement of impingement/effusion cooling roughened by solid rib and slit rib

In the present study, we conducted a conjugate heat transfer (CHT) analysis for double-wall cooling with impingement and effusion, incorporating various types of ribs, using the Reynolds-averaged Navier–Stokes (RANS) method and the modified shear stress transport (SST) turbulence closure model (SST-KIC), accounting for the Kato-Launder modification (K), intermittency (I), and crossflow (C) transition effects. We comprehensively discussed the impact of slit type (parallel, inclined, convergent, and divergent), open-area ratio (β = 5%, 20%, and 40%), and jet Reynolds number on the turbulent flow and heat transfer in a double-wall cooling with slit ribs. Our findings indicated that the introduction of slit ribs significantly improved heat transfer and its uniformity on the target wall, albeit with a slight increase in pressure loss. The overall Nusselt number and thermal-hydraulic performance (THP) in cases with slit ribs gradually decreased with β, yet remained up to 17% and 13% higher than those observed on a smooth target wall. Notably, the open-area ratio of the slit rib exhibited a more pronounced effect on heat transfer over the target plate. For the divergent slit rib within the Reynolds number range of 4000–16 000, the heat transfer enhancement ratio reached the highest value at β of 0.05. In addition, we computed the entropy production caused by fluid friction and heat transfer, as well as the overall entropy production in double-wall cooling at different β and Re. The analysis revealed that the slit rib target plate performed better than the solid rib target plate, showing a distinct advantage in terms of total entropy production.

THERMAL ANALYSIS OF A PLATE HEAT EXCHANGER (PHE) FITTED WITH CARDING TOOL PATTERNS USING CFD MODELING

Inspired by the wool carding tools, a new plate heat exchanger (PHE) design was developed, tested, and analyzed numerically. The present research work used computational fluid dynamics (CFD) simulations to examine the impact of various parameters, such as the rib type (continuous and discrete), the arrangement type (rectangular, square, and triangular), and the geometrical parameters (transversal and longitudinal pitches) on the PHE hydraulic and thermal performances. A three-dimensional (3D) evaluation of turbulent flow over a plate fitted with carding tool patterns was conducted using the<i> k-ε </i>turbulence model within the Reynolds number range from 400 to 1800. The numerical results were compared to previous experimental research to validate the dependability of the technique, and a mesh independence analysis was performed to confirm the precision and the accuracy of the CFD method. The results show that CFD ANSYS software can effectively predict the pressure drop across the carding tools and provide valuable insights into the fluid flow behavior within the system in terms of calculating the thermal hydraulic performance parameter (THPP) and the thermal effectiveness <i>ε </i>. The ultimate goal of this research work was to identify the ideal arrangement with the highest heat transfer rate and the lowest pressure losses in terms of determining the best THPP. Compared to the conventional chevron-type PHE, the thermal performance of the novel PHE design was enhanced by 25.63% and 47% in terms of nondimensional parameters e and THPP, respectively.

CFD Analysis for the Variation of Velocity inside Different Types of Ribs

Abstract: Heat exchanger is used to accomplish the industrial demand. Heat Exchanger are necessary for nuclear reactors and in chemical engineering, for of large quantity of heat is conveying in a slight space with high heat transmission rates and slight habitation time distributions even it suffers through a disadvantage of larger pressure drop. From my analysis, it is found that the uses of ribs inside the solar heat exchanger increase the heat transfer with increase in Reynolds number. Through analysis, it is also found that the value of heat transfer coefficient increases with increase in Reynolds number, heat transfer coefficient is maximum for rectangular shape rib in both the cases that are during using water and nano fluid as a working fluid. The average heat transfer coefficient ratio graph shows that rib used in the solar heat exchanger with nano fluid flow shows more heat transfer enhancement as compared to a solar heat exchanger with simple water flow. Overall it is found that rectangular shape ribs show more heat transfer coefficient as compared to other rib.

The effect of swallow-shaped bionic ribs on the thermal-hydraulic performance of heat exchanger tubes

This paper combines the bionic structure and multi-vortex longitudinal swirl to enhance the heat transfer in the heat exchanger tube while reducing the increase in flow resistance. The design of the enhanced tube with swallow-shaped bionic ribs is inspired by the aerodynamic profile of the swallow flight process to improve the comprehensive performance. The SST k-ω model is selected for numerical simulation. The study of the effect of TCR (triangular concave rib) bionic rib and TVR (triangular convex rib) bionic rib on the flow field characteristics and thermal–hydraulic performance, and the analysis of the effect of pitch ratio (P*) on the thermal–hydraulic performance of TCR tube. The results show that both types of bionic ribs promote the formation and development of multi-vortex longitudinal swirl and transverse swirl in the tube, strengthening the mixing of hot and cold fluids in the tube, improving the synergy of velocity and temperature fields, and making the temperature distribution in the tube more uniform. When P* = 0.75, Nusselt number of the TCR and TVR enhanced tubes is increased by 52.3 %–65.8 % and 43.3 %–57.9 %, respectively, and friction factor is increased by 92.7 %–202.3 % and 78.7 %–263.9 %, respectively, over the smooth tubes. The effect of P* on the thermal–hydraulic performance of the TCR tube is studied, and the PEC value increases as P* decreases. Compared to smooth tubes, TCR enhanced tubes have improved Nusselt number by 26.4 %–95.6 %, friction factor by 50.4 %-345.8 %, and PEC can reach 1.335 when the pitch ratio P* = 0.5. Consequently, the enhanced tube obtains the good comprehensive performance.

Performance of supercritical carbon dioxide heat transfer in several enhanced tubes under external high-temperature airflow

A precooler is installed in the Synergetic Air-Breathing Rocket Engine to ensure the compressor operates properly at high Mach numbers. To better fit the actual precooler scenario, the present study simulated the flow and heat transfer fields of supercritical carbon dioxide (sCO2) in a horizontal tube in which hot air counterflows outside. In the coolant channel, two types of ribs were selected and added, including rectangular ribs as well as isosceles triangular ribs. The geometry parameters of the rib and its configuration on the flow and heat transfer characteristics of sCO2 were examined in detail. Results show that six out of eight cases revealed an increase in Nut over 100% in the triangular rib, making it the optimal enhanced structure. Compared to rectangular ribbed tubes, triangular ribbed tubes display a different variation trend in Nut with rib height due to the combined effects of fluid disturbance and recirculation zone. Both types of ribs increase their Nut first and then decrease it with the rise of rib pitch, which may be due to the fact that high turbulence zones require several distances to develop. This research can provide theoretical foundations and data support for the design of high-efficiency air-precoolers in the future.

Thermal behaviors and flow profiles in a square channel fitted with X–V modified ribs: A numerical analysis

A novel design of “X–V rib” turbulators is proposed to improve fluid blending and to perturb thermal boundary layer (TBL) in a heat exchanger (HX) duct. Better fluid blending and more highly disturbed TBL are the two important factors for the improvement of HX performance. Effects of X–V rib geometrical parameters including rib height ratios (b/H = 0.05–0.20), rib arrangements (V-tip pointing upstream called “V-Upstream (VU)” and V-tip pointing downstream called “V-Downstream (VD)”) and rib types (I, II and III) on air stream and thermal mechanisms are numerically investigated in a 3D model. The numerical model is solved with the finite volume method (a commercial code) and a commercial program. Laminar air flow (inlet conditions with Re = 100–2000) is a selected range of the present investigation. Firstly, the created numerical model for the ribbed duct is validated with two significant topics: 1. Plain duct validation and 2. Optimum grid elements (grid independence). The validated results show that the ribbed-duct model has great reliability to simulate air stream and thermal characteristics. According to the numerical results, the disturbed TBL is obviously found in all rib types. Moreover, it is observed that the core flow disturbance occurs and improves fluid blending. The outcomes from the present investigation point out that the knowledge about flow structure and thermal mechanism are important guidelines for the development of vortex turbulators and HX improvement. For the thermal assessments, it is found that the best Nusselt number ratio (Nu/Nu0) is 11.80 for the type III X–V rib with b/H = 0.20 in the VD-direction. Additionally, the maximum thermal enhancement factor within our investigated range is 3.48 at Re = 2000, b/H = 0.20, type II X–V rib in the VU-direction.

Motor Boats in the Technology of HDPE with RIB Type Construction

Aim: In 2022, on the lakes Zegrzynskie and the Orzysz, there were carried out tests of a motor boat with a hull made in HDPE technology and a construction similar to a hybrid boat (rigid-inflatable boat, RIB). The aim of the tests was to examine the operational capabilities of the SRB53 motor boats and obtain preliminary information on the configuration of the equipment. Introduction: High performance motor boats should constitute standard equipment of lifeguards. There are motor boats on the market using high density polyethylene (HDPE) for the construction of their hulls. Methodology: The survey involved 57 people, experts, representatives of public administration, NATO soldiers, police, and rescue services, as well as enterprises and non-governmental entities operating in the field of water rescue. The working hypothesis was assumed that probably motor boats as a combination of HDPE technology with a hybrid boat design could match the operational rib boats and have an advantage in terms of durability and resistance to hull damage. A diagnostic survey was used on a small sample with research techniques, i.e., observation, interview, and test, as well as research tools in the form of an observation sheet. The research was prepared, carried out and closed in the following order: development of the research procedure, collection of research material, development of results, theoretical analysis of the obtained material and derivation of conclusions. The scope of the boat study included going away and nailing to the quay, the boat’s behaviours when making turns and abrupt turns in both directions at different speeds, and the hull durability test. Results: The test results and opinions were positive, many advantages of the hull of the tested boat were indicated, with one negative parameter – a higher weight compared to traditional rescue boats. The working hypothesis was proved: motor boats in HDPE technology with a hybrid boat design are equal in terms of operation to RIB boats and are more durable and resistant to impacts. Innovative HDPE technology is useful for boat production. Due to the purpose, different configuration and equipment of the boat should be assumed. Keywords: motor boats, water rescue, polyethylene, technology, innovation

Numerical investigation of heat transfer augmentation of solar air heater with attached and detached trapezoidal ribs

The solar air heater has a low heat transfer coefficient due to the development of a laminar sublayer inside the channel of the solar collector. Adding artificial roughness or ribs to the surface of the wall of the absorber plate is an effective and promising method to increase heat transfer by interrupting the laminar sublayer. In this study, a trapezoidal rib was used to enhance the thermal performance of the solar air heater. The characteristics of flow and heat transfer were numerically analyzed using a RNG k-ɛ turbulent model based on the Reynolds number range of 5000, 10000, 15000, 20000, 25000, and 30000. Eight different types of trapezoidal ribs, arranged in shapes that increase in height towards or against the direction of flow, were studied. Four case studies included a solar collector with attached trapezoidal ribs, while another four case studies included a solar collector with detached trapezoidal ribs. The current research involved validation of the results compared to the previously obtained results and showed good acceptable agreement. The results demonstrated that the best thermal performance ratio of the solar collector was achieved when the ribs were attached and detached to the inner surface of a wall, with an increase in the height of the trapezoidal ribs in the opposite direction of the airflow for all ribs. However, these cases resulted in the highest coefficient of friction ratio. On the other hand, the thermal performance was at its lowest level in the cases where the increase in the height of the attached or detached trapezoidal ribs is in the direction of the airflow.

Heat transfer performance study of microchannel heat sink with composite secondary channels

To enhance the performance of microchannel heat sinks, secondary channels or ribs are oftenused separately. However, the synergistic enhancement of heat dissipation by secondary channels and individually composite with different types of ribs and the factors influencing them are not yet clear. In this study, the numerical simulation software ANSYS Fluent is used for simulation and obtaining the optimal microchannel heat sink structure from diamond, rectangular, back triangular, front triangular and elliptical ribs with secondary channel composite. Firstly, the results show that overall performance of microchannel heat sink with front triangular ribs with secondary channel composite is better than other designs. Secondly, the optimized microchannel heat sink with front triangular ribs and secondary channels outperforms the conventional microchannel heat sink by up to 34% in terms of overall performance when Reynolds number is 200, relative rib width/rib length is 0.633/0.400 and relative secondary channel width is 0.600. Finally, by sensitivity analysis, it is found the effect of relative rib width on heat dissipation is about 60%, the effect of flow rate on pressure drop is about 40%, and the effect of overall performance on relative rib width and relative secondary channel width are about 26% and 25%, respectively.

Flexural behavior of different types of steel-concrete composite decks with perfobond rib or head stud shear connectors

With the advent of long-span bridges, steel-concrete composite decks are increasingly concerning structures to address the fatigue problem, wear of the surfacing, and corrosion of the steel decks. The different types of ribs result in the variety of the cross-sections of the composite decks. Thus, the flexural behavior of different types of steel-concrete composite decks with perfobond rib (PBL) or head stud shear connectors was investigated in this study. The different types of composite decks included steel-concrete composite decks (SCCDs), open-rib stiffened steel-concrete composite decks (OSCCDs), and U-rib stiffened steel-concrete composite decks (USCCDs). For this purpose, the static flexural tests of two USCCDs with PBL or head stud shear connectors were conducted. Parametric analyses were also carried out via finite element models to investigate the effects of the number of ribs, the thickness of the ribs, the thickness of the steel plate, the thickness of the concrete slab, and the spacing of the shear connectors on the flexural behavior of the SCCDs, OSCCDs, and USCCDs with PBL or head stud shear connectors. The results indicated that the types of ribs showed significant influence on the flexural behavior of the composite decks. For the same type of shear connector, the flexural behavior of the USCCDs was significantly higher than that of the SCCDs and OSCCDs. Compared with the SCCDs with PBL or head stud shear connectors, the initial stiffness and ultimate load of the USCCDs with PBL or head stud shear connectors were increased by 314.2% and 354.5%, 62.2%, and 89.3%, respectively. The flexural behavior of the composite decks with PBL connections was larger than that of the composite decks with head stud shear connectors for one type of composite deck. The thickness of the concrete slab showed the highest impact on the flexural behavior of the composite decks, followed by the thickness of the rib, the number of ribs, and the spacing of the shear connector. The thickness of the steel plate showed a slight influence on the flexural behavior of the composite decks. The ultimate load of three types of composite decks with PBL or head stud shear connectors was increased by more than 46.5% when the thickness of the concrete slab increased from 80 mm to 120 mm. The reduction stiffness method considering the slip effect was proposed to accurately predict the elastic deflections of three types of composite decks. This study can provide some reference for the design and engineering application of the different types of composite decks.

Refined three-dimensional simulation of ribbed bar pull-out tests based on an enhanced peridynamic model

Peridynamic (PD) theory can effectively model discontinuous problems, but it remains a challenging task for refined three-dimensional (3D) simulation of bond-slip behaviors in pull-out tests, particularly when the rib of rebar is considered. The mesh size of the model needs to be small enough (e.g., decimillimetre or 0.1 mm) to simulate various shapes of ribs. Therefore, the scale of the PD model is usually significantly large and the computational efficiency is low. This paper proposes an enhanced bond-based PD (BPD) model to perform a refined 3D simulation of bond-slip behaviors in the ribbed bar pull-out test. In order to reduce the computation scale and improve efficiency, a practical 3D coupled element is developed to couple the fine PD model and coarse finite element (FE) model, where the PD is used to model the regions in concrete and rebar that are close to the interface, while FE model is used to simulate the regions far away from the interface. A computational framework is developed for implicit and static analyses of the coupled PD-FE model. A parallel computing strategy is adopted to improve the computational efficiency, and enhanced concrete and steel BPD models are presented to accurately simulate the nonlinear behaviors and damage of concrete and ribbed rebars. The enhanced PD modeling approach is implemented in an open-source finite element software framework, OpenSees, and verified by a cantilever beam under uniaxial loading conditions and a pushover analysis of an RC column. Based on the enhanced PD, a refined 3D simulation of ribbed rebar pull-out tests is performed. The bond-slip behaviors are studied in detail, e.g., the crack propagation with different types of ribs, concrete strengths, and rebar properties. The enhanced PD modeling approach provides an effective tool for refined simulation of the complicated bond-slip behaviors in RC structures.

Numerical Investigation of the Ribs’ Shape, Spacing, and Height on Heat Transfer Performance of Turbulent Flow in a Flat Plate Heat Exchanger

This paper presents a numerical study of detailed heat transfer and flow field characteristics in a flat plate heat exchanger with different types of ribs (rectangular and triangular) with different heights (H: 2.5, 5, 7.5, and 10 mm) and spacings (S: 75, 95, 128, and 195 mm). A comprehensive numerical model was established and validated with experimental data in the literature, resulting in good agreement. The effects of the height, spacing, and shape of the ribs in addition to thermal-hydraulic parameters were investigated over two values of the Reynolds number (9880–3210). The results concluded that the highest values of the thermal-hydraulic parameters are 1.62 and 1.84 for the hot and cold air sides, in the rectangular ribs, with a thickness, height, and spacing of 75 mm, and 95 mm, respectively. It is worth mentioning that the rectangular ribs have the maximum value of thermal performance at the high and low values of the Reynolds number of turbulent flows. The present design can be used in waste heat recovery systems.