Number Of Undulations Research Articles

Innovative use of depth data to estimate energy intake and expenditure in Adélie penguins.

Energy governs species' life histories and pace of living, requiring individuals to make trade-offs. However, measuring energetic parameters in the wild is challenging, often resulting in data collected from heterogeneous sources. This complicates comprehensive analysis and hampers transferability within and across case studies. We present a novel framework, combining information obtained from eco-physiology and biologging techniques, to estimate both energy expended and acquired on 48 Adélie penguins (Pygoscelis adeliae) during the chick-rearing stage. We employ the machine learning algorithm random forest (RF) to predict accelerometry-derived metrics for feeding behaviour using depth data (our proxy for energy acquisition). We also build a time-activity model calibrated with doubly labelled water data to estimate energy expenditure. Using depth-derived time spent diving and amount of vertical movement in the sub-surface phase, we accurately predict energy expenditure (R2=0.68, RMSE=344.67). Movement metrics derived from the RF algorithm deployed on depth data were able to accurately (accuracy=0.82) detect the same feeding behaviour predicted from accelerometry. The RF predicted accelerometry-estimated time spent feeding more accurately (R2=0.81) compared to historical proxies like number of undulations (R2=0.51) or dive bottom duration (R2=0.31). The proposed framework is accurate, reliable, and simple to implement on data from biologging technology widely-used on marine species. It enables coupling energy intake and expenditure, which is crucial to further assess individual trade-offs. Our work allows us to revisit historical data, to study how long-term environmental changes affect animals' energetics.

Characteristics and Efficiency of Heat Transfer for Natural Convection by Ag-CuO/H2O Hybrid Nanofluid Inside a Square Cavity with Corrugated Walls

A parametric numerical study is conducted on laminar natural convection and heat transfer in a cavity with opposing undulated walls saturated with a hybrid Ag-CuO/water nanofluid. The two vertical walls of the sinusoidally undulated cavity are maintained at hot and cold temperatures, while the upper and lower walls are thermally insulated. The investigation examines the effects of relevant parameters such as the sinusoidally undulated geometry of the walls for different volumetric fractions of nanoparticles (0% ≤φ≤6%) and Rayleigh numbers (103 ≤ Ra ≤ 106) Thefinite-volumee discretization method is employed to solve the system of governing equations. The results indicate that an increase in the volumetric fraction of nanoparticles enhances the heat exchange rate in the cavity. Additionally, the Rayleigh number, with a significant increase in surface area, strongly influences the dominant heat transfer mode in the cavity. Furthermore, an increase in the number of wall undulations leads to a reduction in the heat transfer rate.

Real performance analysis of drape of virtual cotton fabric based on Style3D

PurposeTo investigate whether the actual effects of eight drape characteristics of virtual fabrics can be manifested in the Style 3D software.Design/methodology/approachImage analysis was conducted using MATLAB software to obtain the drape characteristics of virtual fabrics. Pair the drape characteristics of the real and virtual fabrics for difference. The S-W method was used to conduct a normality test to obtain the correlation of paired samples. A paired sample t-test was performed to obtain the significance values.FindingsThe simulation restoration performance of the drape coefficient, number of undulations, maximum undulation angle, minimum undulation angle and undulation angle uniformity was good. However, there are differences in the simulation performance of the other three indicators: maximum undulation amplitude, minimum undulation amplitude and undulation amplitude uniformity compared to the drape characteristics of real fabrics.Originality/valueProvides reference value for the improvement of Style3D software in virtual fabric simulation and finds the main influential parameters and their impact levels that contribute to the realistic representation of virtual fabrics in software. It provides a theoretical basis for course teaching in digital fashion.

Analysis of magneto-natural convection and second law of thermodynamics of Cu-Al2O3-hybrid nanofluid in a vertical wavy cabinet having a localized non-uniform heat source

Improvements in thermal transference rate and minimization of entropy generation are critical issues in many industrial and engineering applications where heat transfer coefficient is essential to achieve optimal performance and minimal energy consumption. In the present investigation, a computational analysis has been conducted to analyze the impact of magnetic field on magneto-free convection and entropy generation inside a vertical wavy cabinet filled by Cu-Al2O3/H2O hybrid nanosuspension. In the geometry of this model, vertical boundaries of the chamber are designed as wavy and kept as cooled temperature (Tc), whereas the horizontal boundaries are modeled as square and are designed to be thermally adiabatic, except the centrally heated portion on the bottom wall. The centered bottom heated section is supposed to be isothermal with linearly changing temperature, and it changes linearly from Th1 to Th2, whereas it is modelled as a non-isothermal condition. The main focus, in this investigation, is on the entire chamber filled with the combination of hybrid nanoparticles regarded the volumetric concentration of copper and alumina nanoparticles (Cu-50 %+Al2O3-50 %) along with base liquid (H2O). The transformed dimensionless partial differential equations were solved by using finite volume method (FVM) with power law differencing scheme. The simulated flow and temperature fields are scrutinized by streamlines, isotherms, entropy formations, total entropy generation and average convective Nusselt number associated with varying number of undulations (0 ≤ N≤3) volume fraction of hybrid nano liquid (0 ≤ φ ≤ 0.04) magnetic orientation angles (0° ≤ ς ≤ 135°), Hartmann number (Ha = 0 and 50), and dimensionless temperature drop (Ω = 0.001–0.1). From this study, it is found that the average Nusselt number and entropy generation increase as the solid volume fraction of hybrid nanoadditives increases, while opposite trend is observed when the values of Hartmann number rises. The findings show that growth of undulation number (N) causes the reduction of convective heat transfer rate as well as average entropy production intensity. The obtained outcomes concluded that hybrid nano liquid is more effective and finest choice for the improvement of cooling of heat transfer process and minimal energy loss than single nanoliquid. According to the new proposed criterion (TPC), the results show that square-shaped enclosure (N=0) manifests the better cooling performance among the considered governing parameters. The novelty of this study is to scrutinize the flat/ vertical wavy boundaries of the cabinet which can be represented as a model of heat transfer controller, in which it manages the thermal and flow field characteristics. Predominantly, the isothermal line source is used to boost the overall convective heat transfer which is applied in buildings and fluid-mounted heaters. Additionally, many investigators have focused only on the enhancement of heat transfer. As it is known, to increase the thermodynamic efficiency of a system, optimization of entropy generation is an excellent tool which reduces the loss of energy. Hence, it recently does a good engineering sense to highlight an entropy irreversibility.

Revolutionizing bioconvection: Artificial intelligence-powered nano-encapsulation with oxytactic microorganisms

Using incompressible smoothed particle hydrodynamics (ISPH), this study examines the bioconvection flow of oxytactic microorganisms in a porous annulus populated by nano-encapsulated phase change material (NEPCM). Artificial neural network (ANN) is joined with the ISPH method to accurately predict the values of average Nu‾. Between the outside hexagonal-shaped domain and the embedded wavy cylinder, a new annulus is produced. The ranges of the pertinent parameters are wave amplitude of an embedded cylinder A=0.1−0.5, Hartmann number Ha=0−80, a radius of the cylinder Rcyld=0.05−0.5, Darcy number Da=10−2−10−5, undulation number Kund=2−32, bioconvection Rayleigh number Rab=1−1000, Rayleigh number Ra=103−106, and Lewis number Le=1−20. The regulated geometric characteristics of an embedded wavy cylinder, such as wavy amplitude, cylinder radius, and undulation numbers, have been found to contribute significantly to widening the cooling region and minimizing the oxytactic microorganisms. Hence, the embedded wavy cylinder can be applied for various thermal uses including cooling devices and heat exchangers. The average Nu‾ is enhanced under an increment in the geometric parameters of the embedded cylinder. Increasing Rayleigh/bioconvection Rayleigh numbers enhances the buoyancy forces that accelerate the velocity field.

Tribo-Dynamic-Wear coupling analysis for Water-lubricated Bearings with journal surface imperfection under repeated start-stop cycles

Water-lubricated Bearings (WLBs) are the core transmission components of a ship propulsion system, and their wear behavior primarily occurs during the starting and stopping states. To characterize the wear behavior of WLBs, an equivalent experiment is conducted on bush material to obtain the relationship between dimensionless wear coefficient and sliding distance based on the Archard wear model. Then, an experimentally determined transient wear model is incorporated into a tribo-dynamic model to develop a fully coupled Tribo-Dynamic-Wear (TDW) model for the WLBs during repeated start-stop cycles. In this model, the 3D thermal effect, the transient bush worn surface and the geometric imperfection of the journal surface are considered. Numerical results show that the wear rate is more significant at the beginning of the start-up state and the end of the stopping state of the WLB. Meanwhile, it is found that compared to a perfect journal, a reasonable undulation number and undulated amplitude of the journal surface can improve the wear resistance performance of WLBs during repeated start-stop cycles. More specifically, a relatively lower undulation number leads to a smaller wear volume than the perfect journal, and the undulated journal surface has an optimal undulated amplitude that minimizes the wear volume.

Shape optimization study for heat and mass transport of magnetic fluid in a closed domain using a nonhomogeneous dynamic model

The current study deeply investigates nanofluid's heat and mass transport in a staggered-shaped enclosure with wavy walls. A nonhomogeneous mathematical model with thermophoresis and Brownian diffusion is considered in our study. The finite element method is implemented to solve the set of governing equations. Impacts of magnetic field (B0) and its orientation (γ), undulation number (N), amplitude (A) and nanoparticle types are examined for heat and mass flow. Investigations show that the most demoting trend is obtained when the inclination of B0 is either vertical or horizontal. It is concluded that mean Nusselt (Nuavg) and Sherwood number (Shavg) are increasing functions of Ra. When Ra is changed from 103 to 107, the Shavg value is increased up to six times. The impacts of wall shape show that as we increase A, the Nuavg decreases while the maximum can be obtained for the flat boundary. For small N, Shavg is an increasing function. Shape optimization revealed that there exists a critical point between Shavg and N after which it declines. Investigations further show that this point can be changed. Some critical points have been calculated that can be counted as novel results.

Thermo-magnetic convection of MHD Casson fluid in a wavy triangular porous cavity with embedded a cold inverted triangle obstacle

The design of enclosures is crucial in thermal engineering applications and technologies, encompassing areas such as electronics, heat transfer devices, power reactors, heating systems, solar panels, and nuclear power plants. Thermal efficiency in microchannels is optimized and improved by using triangular enclosures with varying aspect ratios. Specifically, the purpose of these triangular enclosures with cool cylinders is to reduce energy loss in nanoscale thermal sinks and thermal exchange devices. The current study aims to explore the thermal radiation effects on magnetohydrodynamic MHD Casson fluid flow within a wavy triangular cavity that includes an embedded cold inverted triangle. The inner inverted triangle is kept at a lower temperature, while the wavy bottom wall of the outer triangular cavity acts as an isothermal heat source at a higher temperature. The numerical solution for this mathematical model is obtained using the open-source finite element software COMSOL. In this study, the wavy triangular enclosure is analyzed for key parameters such as Casson parameter β , Hartmann number Ha , Rayleigh number Ra , numbers of undulation N , radiation Rd and inclination γ . The study presents the local distribution of streamlines, velocity profiles, isothermals, and entropy production, along with the Nu avg . The results reveal the rate of heat transport and total entropy production raise with the increasing number of undulations N and the Casson parameter β , while they decrease with increasing Hartmann number Ha . The number Nu avg rises with the increasing radiation parameter Rd and Rayleigh number Ra . The maximum stream function is observed at an inclination angle of 60 ° .

Effect of Wavy Interface on Natural Convection in Square Cavity Partially Filled with Nanofluid and Porous Medium using Buongiorno Model

nvective heat transfer improvement from wavy surfaces presents a new solution in industrial engineering for composite materials, including porous medium, and nanofluids to address the wavy irregular surfaces in heat transfer devices such as a wavy solar collector, energy absorption and filtration, thermal insulation, and geothermal power plants. This technique enables the performance of engineering applications. The numerical study is performed to examine the effects of a wavy interface separating two layers in the enclosure on heat exchange rates. This paper investigates numerically the natural convection flow in a square cavity partially filled with nanofluid-porous layers separated by a wavy horizontal interface. The left and right walls of the cavity are maintained at constant hot and cold temperatures, whereas the other walls are adiabatic. The Buongiorno model is used to describe nanofluid motion, taking into account the brownian and thermophoresis effects in the cavity. The Galerkin finite element method was applied to solve the differential governing equations. The dynamic, thermal field and heat transfer have been analyzed for various parameters such as Rayleigh number (10^3 ≤ Ra ≤ 10^6), the amplitude of interface (0 ≤ A ≤ 0.1), and undulation number (0 ≤ n ≤ 9). The results reveal that the flow intensity induced by buoyancy forces is more significant in the nanofluid layer than in the porous layer, since the heat transfer is enhanced while the flow is not sensitive to variations in amplitude and number undulation, and accordingly, the decline of average Nusselt and Sherwood numbers is insignificant. The effects of controlled parameters on the structure of nanofluid flow, heat, and mass transfer rate are insignificant.

Exploring the complex interplay of factors in convective heat transfer: a comprehensive parametric analysis in three-dimensional permeable cavities

ABSTRACT This examination aimed to mathematically investigate the blended convective intensity movement inside a three-layered nook that consolidates a spinning roundabout chamber and an undulating permeable pit. Using the limited component technique (FEM), mathematical reproductions were executed across different boundaries, enveloping the Darcy number going from 10 − 5 to 10 − 2 Hartmann number (going from 0 to 100, the angular velocity between − 4000 and 4000, and the number of undulations in the permeable pit. The results, addressed through stream capability, isotherms, and isentropic forms, clarify the effect of these boundaries on movement, heat transport, and entropy age. The ends suggest that for an ideal upgrade of intensity move rates in a three-layered undulating permeable cavity with a pivoting chamber and exposed to an attractive field, explicit circumstances are suggested, a Darcy number more prominent than or equivalent to 10 − 2 , a Hartmann number of 0, undulation of the permeable pit (N = 3), and angular velocity surpassing 2000 in the stream heading. The study investigates convective heat transfer in a rotating cylindrical chamber, analyzing parameters like Darcy number, Hartmann number, and rotation speed for optimizing heat transfer systems in complex porous cavities. The optimal heat transfer occurs when the aspect ratio is fixed at 0.3 and porous media occupies 90% of the channel. A 150% enhancement in the Nusselt number can be observed when the cylinder’s rotational speed increases. The study also found that increasing angular velocity and Darcy number positively affects the Nusselt number. The research aims to understand the interplay of factors affecting convective heat transfer and fluid dynamics and offer practical implications for optimizing heat transfer systems. The novelty of this study lies in its thorough examination of convective heat transfer in a rotating cylinder-shaped porous cavity, focusing on factors like Darcy number, Hartmann number, rotation speed, and pit geometry. It provides insights for optimizing heat transfer efficiency in complex cavities and explores the impact of external magnetic fields and fluid dynamics. The study investigates the influence of parameters like Hartmann number, angular speed, and Darcy number on thermal and flow characteristics in a porous cavity filled with Fe3O4/MWCNT-water nanofluid, highlighting their importance for optimizing heat transfer efficiency.

MHD natural convection in a wavy nanofluid enclosure with an internally corrugated porous cylinder

The present work focuses on investigating magnetohydrodynamic (MHD) natural convection in a complex I-shaped enclosure with corrugated walls, filled with nanofluid and porous media layers. This study analyzes various parameters' effects on heat transfer and fluid flow. The enclosure's left and right walls maintain low temperatures, while the other walls are insulated. The inner corrugated cylinder experiences high temperatures. The study examines the impact of Rayleigh number (Ra), Hartman number (Ha), nanofluid volume fraction (ϕ), Darcy number (Da), MHD inclination angle (γ), position of the corrugated cylinder (δ) and number of undulations (N) on isotherms, streamlines, velocity profiles and average Nusselt number variations. The results show that higher Ra values increase the average Nusselt number while increasing Da enhances it by 65%. Magnetic source inclination greatly affects heat transfer, with Nusselt at γ = 90° being 15.34 compared to 10.234 at γ = 0°. The study concludes that optimal heat transfer occurs at γ = 90°, Ra = 106, Da = 10−3, Ha = 30 and N = 2.

In vivo assessment of early effects of diamond-tipped microdermabrasion through the lens of line-field confocal optical coherence tomography.

Microdermabrasion is a cosmetic procedure that has gained popularity for skin rejuvenation by causing repetitive intraepidermal injury to stimulate the proliferation of fibroblasts and collagen production. Various clinical studies have demonstrated microdermabrasion's effectiveness in skin rejuvenation; however, most of these studies rely on clinical observation and scoring by observers rather than histologic or microscopic analysis. In our single-center prospective study, we used line-field confocal optical coherence tomography (LC-OCT), to non-invasively visualize the early effects of one microdermabrasion treatment on the facial epidermal and dermal structure. Using LC-OCT, this study aims to elucidate the microscopic and histological effects of microdermabrasion on epidermal and dermal structures, including epidermal thickness, as well as collagen and vascular patterns. Eight volunteers (Fitzpatrick skin types II-V) underwent one treatment of microdermabrasion. LC-OCT and VISIA imaging were performed before and 10 min after microdermabrasion, and at 48-h follow-up. Subjective evaluations of skin texture and adverse reactions were assessed 1 week posttreatment via a telephone call. Compared to LC-OCT images before treatment, images captured after one treatment of microdermabrasion showed a decrease in thickness and number of undulations in the stratum corneum. In the superficial dermis, enhancement in fibrillar collagen, as demonstrated by an increased prominence of crisscrossing hyper-refractile strands, was visualized. This was consistent with subjective and objective improvement in facial rhytids calculated by VISIA skin analysis. Treatment monitoring with LC-OCT demonstrated consistent histopathological changes with clinical visual improvement. Therefore, LC-OCT, has the potential to enable long-term histopathological monitoring of microdermabrasion and other cosmetic procedures without biopsy.

Investigation of free convection in a wavy trapezoidal porous cavity with MWCNT- Fe3O4/Water hybrid nanofluid under MHD effects: Galerkin finite element analysis

Our study focuses on numerically investigating natural convection within a three-dimensional trapezoidal cavity featuring a corrugated hot bottom wall, with a particular emphasis on enhancing heat exchange using a water-based hybrid nanofluid. Employing a steady-state regime assumption, the study considers laminar and incompressible three-dimensional flow. The Darcy-Forchheimer model is incorporated to account for inertial advection effects within the porous layer. Predictions of the thermal and hydrodynamic behaviors of the system are achieved by solving dimensionless equations utilizing the Galerkin Finite Element Method (GFEM). Notably, a range of influential parameters, including the volume fraction of nanoparticles (φ), Darcy number (Da) spanning from 10−5 to 10−2, Hartman number (Ha) across the range of 0–100, φ within the range of 0–0.08, porosity (ε) ranging from 0.2 to 0.9, and Rayleigh numbers (Ra) varying from 103 to 106 was explored. The investigation also evaluates the geometrical impact of the enclosure by considering undulation numbers (N) of the warm bottom ranging from 1 to 4. Our results provide novel quantitative insights. Specifically, we observe an inverse relationship between undulation number (N), Hartman number (Ha), and porosity (ε) with large Rayleigh (Ra) flows, significantly influencing effective heat transfer. Notably, this influence diminishes at lower Ra flows. At the highest Ra, we find that increasing Da, ε, and φ enhances the Nusselt number (Nuavg) by 26 %, 17 %, and 23.5 %, respectively. Conversely, increasing Ha and N reduces Nuavg by 13 % and 40 %, respectively. These findings highlight the nuanced interplay of parameters and offer valuable quantitative data for optimizing heat transfer processes in similar systems.

Entropy generation in a partially heated hybrid nanofluid saturated wavy porous cavity

PurposeA porous cavity flow field generates entropy owing to energy and momentum exchange within the fluid and at solid barriers. The heat transport and viscosity effects on fluid and solid walls irreversibly generate entropy. This numerical study aims to investigate convective heat transfer together with entropy generation in a partially heated wavy porous cavity filled with a hybrid nanofluid.Design/methodology/approachThe governing equations are nondimensionalized and the domain is transformed into a unit square. A second-order finite difference method is used to have numerical solutions to nondimensional unknowns such as stream function and temperature. This numerical computation is conducted to explore a wide range of regulating parameters, e.g. hybrid nano-particle volume fraction (σ = 0.1%, 0.33%, 0.75%, 1%, 2%), Rayleigh–Darcy number (Ra = 10, 102, 103), dimensionless length of the heat source (ϵ = 0.25, 0.50,1.0) and amplitude of the wave (a = 0.05, 0.10, 0.15) for a number of undulations (N = 1, 3) per unit length.FindingsA thorough analysis is conducted to analyze the effect of multiple factors such as thermal convective forces, heat source, surface corrugation factors, nanofluid volume fraction and other parameters on entropy generation. The flow and temperature fields are studied through streamlines and isotherms. The average Bejan number suggested that entropy generation is entirely dominated by irreversibility due to heat transport at Ra = 10, and the irreversibility due to the viscosity effect is severe at Ra = 103, but the increment in s augments irreversibility due to the viscosity effect over the heat transport at Ra = 102.Originality/valueTo the best of the authors’ knowledge, this numerical study, for the first time, analyzes the influence of surface corrugation on the entropy generation related to the cooling of a partial heat source by the convection of a hybrid nanofluid.

Numerical investigation of forced convection flow of a complex Bingham–Papanastasiou fluid between two concentric

This research presents a numerical investigation of the flow field and heat transfer of a Visco-plastic fluid, The Bingham-Papanastasiou model is used to examine the flow field and forced convection heat transfer of a Viscoplastic fluid between two concentric cylinders with a wavy inner surface. By focusing on this particular configuration (wavy inner cylinder shape), where the inner surface exhibits as the hot wall while the outer surface is considered as the cold wall. This investigation is numerically achieved by using the Comsol Multiphysics, which is based on the finite‐volume method, employing Galerkin’s method for solving the governing equations. The parameters studied in this research are expressed with the following values: r/ R=1/3, Reynolds number (Re=1, 10, 50), and undulation number (nu=0, 6, 12, 24). Increasing the inertia parameter results in a higher intensity of thermal buoyancy, positively influencing heat transfer, particularly at Re=50. Furthermore, the acceleration of flow within the investi-gated space improves the hydrodynamic behavior, facilitating the exchange of thermal energy between the hot and cold walls. Additionally, it has been discovered that an undulating shape with a specific number of undulations (nu=6) maximizes hydrothermal performance within the investigated volume. The presence of these undulations enhances fluid mixing and dis-rupts the formation of stagnant regions ,which leading to improved heat transfer.

Enhanced conjugate natural convection in a corrugated porous enclosure with Ag-MgO hybrid nanofluid

Understanding the impact of hybrid nanofluids (NF) on natural convection (NC) within complex enclosures can significantly advance the efficiency of heat transfer (HT) mechanisms. These advancements play a crucial role in various engineering applications, such as thermal systems in electronics, energy conversion, and heat exchangers. This study numerically examined the NC taking place within a sinusoidal corrugated enclosure filled with an Ag-MgO hybrid NF. This system was heated differentially by a vertical solid wall. The vertical right wall of the solid is maintained at an isothermal at a high-temperature Th, while the left vertical wall of the cavity is kept at an isothermal at a low-temperature Tc. The vertical left wall of the solid is in contact with the porous medium (PM) saturated with the cavity's hybrid NF. In contrast, the top and bottom horizontal walls are maintained adiabatic. The governing equations were solved by employing the Galerkin weighted residual finite elements approach. The porous domain is modeled by employing the Darcy-Brinkman formulation. The parameters being studied encompass the Darcy number (10−5 ≤ Da ≤ 10−2), Rayleigh number (103 ≤ Ra ≤ 106), nanoparticle volume fraction (0 ≤ ϕ ≤ 0.04), amplitude of waviness (0.05 ≤ A ≤ 0.2), and number of undulations (1 ≤ N ≤ 4). The results highlighted that the introduction of hybrid nanoparticles into the pure fluid enhances the HT rate across the parameter spectrum. The highest average Nusselt number (Nuav) is attained at Ra = 106, Da = 10−2, A = 0.2 and N = 4. The findings of the current study have practical implications for current industrial applications, particularly in the cooling of electronic devices.

A ROTATING WAVY CYLINDER ON BIOCONVECTION FLOW OF NANOENCAPSULATED PHASE CHANGE MATERIALS IN A FINNED CIRCULAR CYLINDER: ISPH SIMULATIONS

The originality of this study is the introduction of numerical investigations on the bioconvection flow of nano-encapsulated phase change materials (NEPCMs) with oxytactic microorganisms in a new configuration of a circular annulus with a rotating wavy inner cylinder. The incompressible smoothed particle hydrodynamics (ISPH) method was applied to solve the governing partial differential equations for the velocity, temperature, concentration, and density of motile microorganisms. Compared with the conventional mesh-based method, this mesh-free, particle-based approach offers strong advantages in the simulation of complex problems with free surfaces and moving boundaries with large displacements. The pertinent parameters are the undulation number (<i>N<sub>und</sub></i> = 2-36), bioconvection Rayleigh number (<i>Ra<sub>b</sub></i> = 1-1000), Darcy parameter (Da = 10<sup>-5</sup>-10<sup>-2</sup>), length of the inner fin (<i>L<sub>Fin</sub></i> = 0.05-0.15), radius of the inner wavy cylinder (<i>R<sub>c</sub></i> = 0.05-0.25), Rayleigh number (Ra = 10<sup>3</sup>-10<sup>5</sup>), undulation amplitude of the inner wavy cylinder surface (<i>A</i> = 0.1-0.4), and frequency parameter (<i>ω </i>= 1-5). The undulation number of the inner wavy cylinder enhanced the flow of the oxytactic microorganisms and isotherms, whereas it had the reverse effect on the velocity, decreasing the maximum velocity by 26.56%. In addition, the comparatively high undulation amplitude and frequency increased the average Nusselt and Sherwood numbers. It was found that the embedded wavy cylinder interacting with fins plays an important role in enhancing heat transfer and the bioconvection flow within a closed domain.

A Galerkin finite element-based study of MHD mixed convective of Ostwald-de Waele nanofluids in a lid-driven wavy chamber

This paper presents a Galerkin finite element-based study investigating the magnetohydrodynamic (MHD) mixed convective behavior of Ostwald-de Waele nanofluids in a lid-driven wavy chamber. The study addresses a critical aspect of heat transfer with applications in diverse fields, including nuclear power plants and solar thermal collectors. Utilizing Galerkin finite element methods, we analyze the complex interplay of factors in the 2D stable motion of nanofluids. Our investigation involves a comparative analysis of thermal Grashof numbers, emphasizing their impact on the thermo-hydrodynamic behavior within the chamber. Additionally, the magnetic field effects, characterized by parameters such as Hartmann number, Reynolds number, Darcy number, power-law index, and undulation number, are systematically explored. The study introduces geometric representations for understanding the isothermal behaviors of Ostwald-de Waele nanofluids. The findings underscore the significance of physical factors, including the transition to turbulent flow, increased porosity, enhanced nanoparticle strength, and smaller particle sizes, in influencing fluid flow within the chamber. Notably, at the highest Reynolds number, elevating Grashof and Darcy numbers enhances the Nusselt number by 3% and 19%, respectively, while a reduction in the Hartmann number leads to a remarkable 23% increase. This Galerkin finite element-based study provides a comprehensive examination of MHD mixed convective behavior in a lid-driven wavy chamber with Ostwald-de Waele nanofluids. The results offer quantitative insights into the intricate dynamics of nanofluid heat transfer and contribute novel perspectives to the existing literature.

A novel strategy of enhanced thermal performance in air cooled lithium-ion battery by wavy walls

Electric vehicles (EVs) with rechargeable lithium-ion batteries are one of the most appealing choices for electrochemical energy storage to address global energy challenges and environmental concerns caused by rising carbon emissions. However, to maintain the performance and longevity of these high power batteries, a well-planned and effective cooling mechanism is required. Here, a novel air-based battery thermal management system (BTMS) is proposed to realize an improved cooling performance. We examined the thermal performance of an air-cooled lithium-ion battery pack of 3x5 Sony 18650 cells by introducing wavy (undulated) sidewalls for the discharge period of the cells. Influence of air inflow velocity (U0) and number of undulations on wavy wall have been delineated at a discharge rate of 2C and 3C. As obvious, the cooling improves with the increasing U0. Interestingly, a significant reduction (∼ 8-10 K) in the average and maximum cell temperature was seen simply by creating an optimal number of undulations on the walls as compared to the results obtained from straight walls. The highest cooling performance was observed when the undulations form a trough above the cells, however, the highest pressure drop was experienced in such cases. A trade-off between the cooling enhancement and power requirement (∼ pressure drop) has been presented by a performance plot. Finally, the efficacy of system was ensured by changing the number of rows and columns of the cell arrangement in the battery pack. An enhanced heat dissipation and thermal uniformity was seen in all the cases when wall undulations are present.

Nanofluid thermo-bio-convection in a horizontal porous wavy-walled annulus: Interaction of phototactic microorganisms and nanoparticles distribution

Transport phenomena related to thermo-bioconvection have recently emerged as an intriguing area of study because of their multi-physical applications such as bio-energy systems, food industries, solar collectors, pollutant dispersion in aquifers, biological wastes processing, chemical catalytic converters, geothermal energy usage, petroleum oil reservoirs, enhanced oil recovery, thermal energy storage, chemical processing equipment, fuel cell technology, medical application, microfluidic devices, and others. In this context, it is highly challenging to design and regulate a system with multi-physical transport in a complex geometry. The goal of the current study is to analyze the thermo-bioconvective heat transfer induced by a gradient of temperature and a motile of phototactic microorganisms with the presence of two types of nanoparticles inside a wavy-walled horizontal cylindrical porous annulus. The originality of this investigation is analyzing the influence of microorganisms, waviness parameters and hybrid nanofluid on thermo-convective instabilities. The effects of the wall waviness parameters, bioconvection Rayleigh number (Rab), thermal Rayleigh number (RaT), nanoparticles volume fraction ϕ and Lewis number (Le) on the flow structure, temperature, and isoconcentrations of microorganisms are investigated and explained in detail. The key findings showed that the Lewis number impacts the onset of thermo-convection and bioconvection and convection phenomena begins rapidly for small values of Lewis number. The nanoparticles enhance the heat transfer in case of thermo-bioconvective flow in a horizontal porous cylindrical system. The average Nusselt number Nu¯ decreases as the wall waviness parameters, amplitude λ, and undulation number η increase. It was also shown that thermo-convective instabilities may develop depending on thermal Rayleigh number, bioconvection Rayleigh number, nanoparticles volume fraction and wall waviness parameters.