Wavy Sidewall Research Articles

Convective heat transport in a porous wavy enclosure: Nonuniform multi-frequency heating with hybrid nanofluid and magnetic field

This work investigates the dynamics of the hybrid nanofluidic convective heat transfer in a permeable thermal system under the influence of multifrequency heating and a magnetic field. The geometry comprises a wavy-walled cavity filled with a water-based hybrid nanoliquid (Al2O3–Cu–H2O) in a saturated porous medium. The finite volume approach is applied to scrutinize the hydro-thermal characteristics resulting from bottom heating and side cooling, considering various flow-controlling parameters. The analysis reveals that nonuniform multi-frequency heating can be a highly effective strategy for enhancing heat transfer in complex geometries involving porous systems, nanofluid flow, and magnetic fields. Significant heat transfer improvement is observed at higher frequencies, with an increase of approximately 261.49 % when offset temperatures are introduced. Additionally, an increase in the undulation height of the wavy sidewalls contributes to a partial heat transfer improvement of 13.41 % compared to the case without undulations. The influence of the Darcy number, Hartmann number, porosity index, and nanoparticle concentration on heat transfer performance is also investigated. Higher Darcy and Hartmann numbers result in reduced thermal convection, while increased porosity enhances thermal convection. Elevated nanoparticle concentrations weaken the flow strength due to higher viscosity. System engineers can optimize heat transfer systems in their respective applications by comprehending the interactions between these flow-controlling parameters. This work contributes to a deeper understanding of the hydro-thermal phenomena in a multiphysics problem and provides a foundation for the development of more efficient heat transfer systems.

Heat transfer and fluid flow in nano-encapsulated PCM-filled undulated cavity

This article discusses the heat transfer characteristics of the mixed convection of NEPCM-fluid (Polyurethane/ Nonadecane dispersed in water) contained within a wavy-sided walls cavity. Mixed convection is caused by an adiabatic rotating cylinder located in the cavity center, while natural convection results from deferential heating of side walls. The upper and lower walls of the cavity are insulated. The Galerkin finite element method (GFEM) implemented in COMSOL CFD package is employed to solve the governing equations. The influence of the nanoparticles volume fraction (Ø = 0.02, and 0.05), cylinder radius (R = 0.05, 0.15, and 0.25), cylinder rotating speed (Ω = 100, −500, 500, and 1000), the dimensionless fusion temperature (θfu = 0.1, 0.25, and 0.5), wavy side walls undulation peaks number (N = 1 to 4) on the flow pattern and temperature field are presented. The results revealed that the heat transfer enhances by increasing the angular speed of the cylinder and its radius, also an enhancement in heat transfer is obtained by upgrading the volume fraction of NEPCM, however, it was noticed that for small cylinders, the counterclockwise rotation of the cylinder reduced the heat transfer rate as the rotation opposed the direction of natural heat convection. In addition, the waviness pattern has a specific impact on each case, for example, N = 4 denotes the best result for only the cases Ω = -500 or 500 when R = 0.25 and Ø = 0.05, while the heat transfer is negatively affected by increasing N for the other cases. On another hand, the impact of θfu on the heat transfer rate was found to be insignificant. Globally, at the biggest cylinder radius, higher Ø and highest angular speed an enhancement by more than 900 % can be achieved.

Numerical study on flow and heat transfer in a novel symmetric sinusoidal wavy microchannel heat sink with rectangular rib prisms

To enhance thermal and overall performances, a novel microchannel heat sink (SSW-RP) was devised by integrating symmetric sinusoidal wavy sidewalls with rectangular rib prisms within the channels. A numerical comparative study was conducted to explore heat transfer mechanism in channels by investigating the flow and heat transfer characteristics of SSW-RP in comparison with those of smooth straight microchannel (MC), smooth straight microchannel with rectangular rib prisms (MC-RP), and symmetric sinusoidal wavy microchannel (SSW). The results show that the addition of rib prisms makes the fluid flow into wave peaks, reducing and even eliminating vortices from wave peaks of the symmetric sinusoidal wavy microchannel, thus significantly improving heat transfer performance. The new design SSW-RP had the highest relative Nusselt number, which reaches 4.16 at Re = 800. Further, the hydrothermal performance sensitivity of SSW-RP to the relative width (α) and length (β) of rib prisms is studied, and the best overall performance factor of SSW-RP finally can be achieved up to 1.88 at α = 0.35, β = 0.4 and Re = 800.

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.

Natural convection characteristics of nano-encapsulated phase change materials in a rectangular wavy enclosure with heating element and under an external magnetic field

Recently, nano-encapsulated phase change material (NEPCM) has received great attention due to its ability to absorb and release heat, making it a perfect choice for many engineering and industrial applications. The current work examines the natural convection of NEPCM confined in a cubic enclosure having two wavy sidewalls and under the effect of an external magnetic field. The enclosure is heated from below via a duct or cavity having a U shape; both wavy sidewalls experience cold temperatures, and the other walls are thermally insulated. The impacts of different operational and geometrical parameters on heat transfer inside the enclosure were numerically investigated. These parameters include the external magnetic field applied, Rayleigh number (Ra), sidewall wavenumber (N), Hartmann number (Ha), nanoparticle volume fraction (φ), and heat source position. Heat transfer within the enclosure was found to be most affected by the Ra and Ha numbers, while the other factors studied had little to no effect. The maximum local Nusslet number at Ra = 106 was four times greater than that at Ra = 103. As for the effect of the Ha number, increasing Ha from 0 to 100 decreased the average Nusselt number by 38 %.

Heat transfer and entropy generation analysis of water-Fe3O4/CNT hybrid magnetic nanofluid flow in a trapezoidal wavy enclosure containing porous media with the Galerkin finite element method

The present study addresses theoretically and computationally the performance of electrically conducting water-Fe3O4/CNT hybrid nanofluid in three-dimensional free convection and entropy generation in a wavy-walled trapezoidal enclosure. The enclosure has two layers—a hybrid nanoliquid layer and a permeable medium layer. A transverse magnetic field is acting in the upward direction. Newtonian flow is considered, and the modified Navier–Stokes equations are employed with Lorentz hydromagnetic body force, Darcian and Forchheimer drag force terms. The wavy side walls are heated while the top and vertical walls are adiabatic. An elliptic cylindrical cooled fin is positioned at the center of the cavity, and several different tilting angles of the fin are considered. The transformed, non-dimensional systems of coupled nonlinear partial differential equations with their corresponding boundary conditions are solved numerically with the Galerkin Finite Element Method (FEM) using the COMSOL Multiphysics software platform. The impact of Darcy number, Hartmann number, volume fraction, undulation number of the wavy wall and Rayleigh number (thermal buoyancy parameter) on the streamlines, isotherms and Bejan number contours are investigated. Extensive visualization of the thermal flow characteristics is included. With increasing Hartmann and Rayleigh numbers, the average Bejan number is reduced strongly whereas the average Nusselt number is only depleted significantly at very high values of Rayleigh and high Hartmann numbers. With increasing undulation number, a slight elevation in average Bejan number at intermediate Rayleigh numbers is noticed, whereas the average Nusselt number is substantially boosted, and the effect is maximized at a very high Rayleigh number where the average Nusselt number was increased by 35%. An increment in Darcy number (i.e., reduction in permeability of the porous medium layer) is observed to considerably elevate the average Nusselt number at high values of the Rayleigh number up to 20%, whereas the contrary response is computed in average Bejan number, where it showed a reduction by 10 times. The simulations apply to hybrid magnetic nanofluid fuel cells and electromagnetic nanomaterials processing in cavities.

Thermofluidic transport phenomena of hybrid nanofluid in a porous wavy enclosure imposing magnetic fields

The present work outlines an analysis of thermo-fluidic transport phenomena in an undulated walled porous enclosure filled with hybrid nanofluid imposing magnetic field under the free-convective mode of heat exchange. The complex wavy enclosure is heated isothermally from the bottom, whereas the wavy sidewalls are cold. The enclosure is packed with porous material and Cu/Al2O3 water-based hybrid nanoliquid. The externally generated magnetic field acts partially perpendicular to the left sidewall. The governing equations are solved numerically utilizing FORTRAN-based code adopting the finite volume method. The porous structure is modeled using the Brinkman-Forchheimer-Darcy model. The key parameters are judged for the study as modified-Rayleigh number Ram (reflects the convective strength), Darcy number Da (reflects the permeability of the porous structure), Hartmann number Ha (reflects the magnetic field intensity), the volume fraction of hybrid nanoparticles, etc. The results are presented systematically using streamlines, and isotherms contours. The assessment of heat transport is illustrated using the average Nusselt number (Nu) under a wide range of control parameters. It is found that the thermo-fluid flow alters significantly depending on the control parameters. The presence of flow dampening magnetic field and porous structure causes decrement of heat transfer, which is compensated (increment ∼ 9.4%) using the hybrid nanoliquid. The outcome of this analysis can be very useful for designing any device/ system involving thermal energy transportation in diverse fields of applications.

Role of surface undulation during mixed bioconvective nanofluid flow in porous media in presence of oxytactic bacteria and magnetic fields

Transport phenomena involving thermo-bioconvection have become an interesting field of research due to their novel application in various fields of engineering, bio-energy systems, fuel cells, medical science, etc. Design as well as proper control of such a system involving multiphysical transport in a complex geometry is a very difficult task. On such a system, the present study is conducted aiming to examine the magnetohydrodynamic (MHD) mixed bioconvection with oxytactic microorganisms suspended in copper-water nanofluid. The flow takes place through porous media in a top-wall-translating enclosure with a complex wavy sidewall heated uniformly. The right vertical wall is isothermally cooled; other walls are adiabatic. A magnetic field is imposed along the horizontal direction. Evolved flow physics are analyzed by modeling this complex problem involving an undulating heated wall and many coupled transport equations (due to the presence of motile bacteria or organisms) are numerically solved through a finite volume-based code. The thermo-fluid behaviors are studied extensively to explore the controllability of different involved parameters that could help the system's design and operation. The important parameters influencing the complex physics in the enclosure are the number of undulations (n), bioconvection Rayleigh number (Rb), Darcy number (Da), Hartmann number (Ha), Peclet number (Pe), Lewis number (Le), oxygen diffusion ratio (χ), Grashof number (Gr). The study reveals that the undulating curved surface enhances the heat transfer up to certain optimal magnitudes of undulations at the different operating conditions. The mass transfer rate increases with all undulations and bioconvection supports this trend. Bioconvection always favors heat transfer. In general, it is found that by adjusting the involved flow parameters and number of undulations, the local as well as global transport mechanisms, can be controlled effectively. The concept of this investigation could be found in the designing of microbial fuel cells and different nanotechnology-based bioconvection.

A novel spiral channel with the growing waviness on the sidewalls for compact high-efficiency heat exchanger

Spiral channels are widely used as the core heat exchangers in latent thermal storage units. This study aims to develop a novel spiral channel characterized by wavy sidewalls for high-efficiency convective heat transfer in tube side. The amplitude of the wavy sidewalls is designed to grow from the inlet to the outlet along flow direction. The thermal characteristics in the spiral-wavy channel were numerically investigated under the boundary condition of constant wall temperature, since latent heat storage units mainly work under isothermal condition. The comparison was carried out between a smooth-spiral channel and a spiral-wavy channel in terms of the heat transfer capacity, friction factor, dimensionless temperature distributions and development of boundary layers. At a given heat transfer rate, the required length of the spiral-wavy channel is only 63.5% of that of the smooth-spiral channel, which implies that the energy density and efficiency of a heat storage unit can be improved remarkably. The increase in pressure drop brought by the spiral-wave channel is less important compared with the improvement of thermal performance, suggesting its potential in heat transfer enhancement and energy saving. The present work is expected to motivate the design of compact and high-efficiency heat exchangers for thermal energy storage and extraction.

Effects of wave number and average radius on flow and heat transfer in a curve‐wave channel

The demand for high cooling capacity heatsinks has been increasingly promoted due to the fast elevated heat generation of modern electronic devices. High-performance microscale heat exchangers are often accompanied by considerable pressure drop penalty that limits their applications. In order to avoid large pressure drop while maintaining high heat transfer rate, a macroscale curved channel was proposed with applying the periodical wave structure on the channel sidewalls. A three-dimensional conjugated numerical model was established, and the effects of wave number and average radius on the hydrothermal performance were investigated. It was found that the heat transfer performance in the smooth-curve channel is significantly improved due to the wavy sidewalls with a moderate pressure drop penalty. The heat transfer enhancement is more noticeable in the channels with more wave units and smaller average channel radius. Furthermore, it was noted that the periodical thermal entrance effect exists on the inner and the outer convective surfaces of curve-wave channels, which can be attributed to the variations of the secondary flow with the wave direction along the channels.

Impact of nanoparticles migration on mixed convection and entropy generation of a $$\hbox {Al}_{2}\hbox {O}_{3}$$–water nanofluid inside an inclined enclosure with wavy side wall

A numerical study based on the non-homogeneous model of the mixed convection of $$\hbox {Al}_{2}\hbox {O}_{3}$$–water nanofluid in an inclined enclosure is made. The heated side wall of the enclosure is considered to be wavy while the top wall is made to translate horizontally. The wavy physical domain is transformed to a square computational domain through a suitable coordinate transformation. The transformed governing equations are integrated based on the control volume approach in a staggered grid arrangement. A third-order accurate upwind scheme QUICK is used to discretize the convective terms while a central difference type scheme is used to approximate the diffusive terms. The discretized equations along with the specified boundary conditions are solved through a pressure correction-based SIMPLE algorithm. The impact of the inclination angle of the enclosure and surface waviness on the nanofluid mixed convection is elucidated. The parameters governing the Brownian motion, thermophoresis, Lewis number and buoyancy ratio parameter are determined based on the nanofluid thermophysical properties. The effect of the nanoparticle bulk volume fraction and nanoparticle diameter on the mixed convection is analyzed for different choices of nanofluid-to-base fluid thermal buoyancy ratio in the buoyancy-dominated regime as well as shear-dominated regime. A comparison of the non-homogeneous model for the nanofluid with the homogeneous model is also made in this study. The inclination angle of the enclosure is found to have an impact on the mixed convection when buoyancy force is dominant. Heat transfer augmentation occurs as the wave number, and/or wave amplitude of the wavy side wall is increased. The thermodynamic optimization is studied by analyzing the average Nusselt number and the total entropy generation.

Enhanced mixing and flow reversal in a modulated microchannel

Electrokinetic mixing enhancement of an aqueous electrolyte due to advection-diffusion mechanism is proposed in a microchannel with wavy side walls. Usually, the electrolyte movement in polyvinyl chloride or teflon textured surface material leads to the generation of an electric double layer (EDL) because of the attraction & repulsion of counter and co-ions. A transverse electric field is enforced along the horizontal direction to create an electroosmotic flow (EOF) and the channel walls are pretended to be composed of two superimposed sinusoidal waves. The resulting flow field consists of recirculating eddies to achieve an improved passive mixing along the downstream. Through numerical simulations it is predicted that flow advection may be induced by wavy amplitude variation along the channel length. Hence, a parametric estimation is made between the critical wave amplitude for flow separation with the electric field intensity and Debye-Hu¨ckel parameter. The key aspect of this paper is to analyse mixing efficiency as a function of geometric parameter, solution’s molarity and electric field strength.

Experimental investigation of flow boiling characteristics in microchannels with the sinusoidal wavy sidewall

An improved microchannel heat sink with the sinusoidal wavy sidewall (SIN) is designed and fabricated by MEMS technique. The synchronous optical measurement system is established. The flow and heat transfer performance in SIN microchannels is experimentally studied using acetone as the working fluid. At mass fluxes of 251 kg/(m2·s)–423 kg/(m2·s) and heat fluxes of 0 kW/m2–601 kW/m2, the pressure drops, boiling curves, and heat transfer coefficient are investigated and analyzed. The temperatures, pressure drops, and corresponding flow patterns in the stable state are emphatically examined. The experimental results show that, a continuously developing liquid film always exists near the sidewall, which not only timely supplies the liquid for nucleation tending to occur in the corner regions, but effectively prevents the microchannel dry-out. Consequently, the premature onset of nucleate boiling (ONB), the delayed critical heat flux (CHF), and about 100% enhancement of heat transfer coefficient can be achieved with SIN microchannels compared to the traditional rectangular (R) microchannels. In the stable state, all the dominant flow patterns at different positions are almost fixed, which result in stable heat transfer enhancement. The flow pattern transitions between single liquid/bubbly flow, bubbly/slug flow, bubbly/annular flow are observed at the channel midstream in the low/medium/high heat flux, respectively. It is noteworthy that all of the dominant flow patterns at the channel downstream are not vapor flow but annular flow with thin and continuous liquid film. In addition, the flow boiling instabilities characterized by the temperatures and pressure drops with obvious fluctuations are also illustrated.

Effect of inside heated cylinder on the natural convection heat transfer of nanofluids in a wavy-wall enclosure

In this study, natural convection heat transfer of nanofluids in a wavy-wall enclosure is studied while a heated cylinder is located inside the cavity. The governing equations for a simple cavity are studied based on the previous work and changed it to complicated two-phase nanofluid and solved by finite element method (FEM). Because the location on inside cylinder has a significant effect on the heat transfer and Nusselt number, it is important to find the best location for this cylinder. In our study the cylinder is movable in X and Y directions which affects the temperatures, stream lines and nanoparticles concentration contours. The results indicate that center location for the cylinder assists the heat transfer in both wavy side walls.

Highly efficient and reliable high power InGaN/GaN LEDs with 3D patterned step‐like ITO and wavy sidewalls

Nitride‐based high power LEDs with finger‐like SiO2 current blocking layer (CBL), three‐dimensional (3D) patterned step‐like ITO double layers and wavy sidewalls were fabricated. The finger‐like SiO2 CBL beneath finger‐like p‐electrode was designed to prevent current crowding effect, thereby facilitating uniform current spreading over the entire chip. In addition, 3D patterned step‐like ITO double layers, including alternating 230 nm thick patterned upper step ITO layer and 100 nm thick lower step ITO layer, were formed by combining photolithography and aqua regia etchant. We showed that the top light extraction efficiency of high power LEDs can be significantly enhanced by taking 3D patterned step‐like ITO. The light output power of high power LEDs with 3D patterned step‐like ITO double layers is 13.9% higher than that of LEDs with smooth ITO layer. High‐power LEDs with wavy sidewalls was fabricated by an optimized mask design in conjunction with dry etching process based on Cl2/BCl3 to improve light extraction efficiency at the horizontal direction. We demonstrated that light output power of high power LEDs with wavy sidewalls can be improved by 11% as compared to LEDs with flat sidewalls.

Highly efficient and reliable high power InGaN/GaN LEDs with 3D patterned step-like ITO and wavy sidewalls

Highly efficient and reliable high power InGaN/GaN LEDs with 3D patterned step-like ITO and wavy sidewalls

Thermal performance of rotating two-pass ribbed square channel with wavy sidewalls

Detailed Nusselt number (Nu) distributions over Leading Endwall (Le-E) and Trailing Endwall (Tr-E), Fanning friction coefficients (f) and thermal performance factors (TPF) of a radially rotating two-pass square channel enhanced by in-line 45° endwall ribs and wavy sidewalls were measured at the test conditions of 5000⩽Re⩽20,000, 0⩽Ro⩽0.3 and 0⩽Bu⩽0.053. No previous study has examined the thermal performances of a rotating ribbed two-pass channel with wavy sidewalls. A selection of heat transfer data illustrates the individual and interdependent effects of Re, Ro and Bu on local and region-averaged Le-E and Tr-E Nu. A set of Le-E and Tr-E heat transfer correlations that determines the rib-wise and regionally averaged Nu over the inlet and outlet ribbed endwalls, as well as over the smooth bend endwall is generated. Along with the f data detected from the ribbed endwalls and wavy sidewalls at isothermal conditions, the TPF values at various rotating conditions are evaluated. The heat transfer, pressure drop and TPF performances for the two-pass channel with present combined passive Heat Transfer Enhancement (HTE) device at rotating conditions are subsequently compared with those generated by the typical HTE devices deployed in the internal coolant channels of a gas turbine rotor blade. Acting by the combined Re, Ro and Bu effects, present region-averaged Nusselt numbers over the rotating Le-E (Tr-E) of the inlet-leg, sharp bend and outlet-leg are respectively raised to 3.20–5.80 (4.10–8.59), 4.26–10.48 (5.03–15.47) and 1.48–12.47 (4.64–8.24) times of the Dittus–Boelter reference levels. With the f coefficients increased to 9.61–25.7 times of the Blasius equation levels by present HTE measure and the 180° sharp bend, present TPF values obtained at the rotating test conditions fall in the range of 2.87–0.71, suggesting the favorable heat transfer effectiveness with cooling applications to gas turbine rotator blades.

Pinning and wetting stability of liquids on superoleophobic textured surfaces

Super water/oil repellency has been a very active research field and could be achieved via combination of surface texturing and chemical treatment. When a droplet is deposited on a superhydrophobic/superoleophobic surface, its contact line can be pinned somewhere on the structured surface instead of fully wetting the substrate, forming a solid–liquid–air composite interface. The focus of this article is to understand the effect of pinning and wetting stability through energy analysis and force balance. Textured surfaces with straight sidewall pillar, wavy sidewall pillar and hoodoo structures are discussed in detail. For the straight sidewall structure, it was found that the top pillar edge is a stable pinning site for water. Meanwhile, hexadecane fully wets the structure without any pinning. On the wavy sidewall structure, the protruding and concave corners are pinning sites for both water and hexadecane. However, the dominant breakthrough pressure comes from the energy barrier against contact line advancing along the re-entrant slope of the wave. On the hoodoo structure, there are two pinning sites (top and bottom corner of the hoodoo cap) for water, but only one pinning site (bottom corner) for hexadecane. The effects of solid area fraction and re-entrant angles on pinning stability are studied with the wavy sidewall structure. This study suggests that Gibbs energy analysis can be a viable approach in designing robust superoleophobic surfaces by enhancing the pinning stability and breakthrough pressure, which is strongly correlated to design parameters, for example solid area fraction, geometrical re-entrant angle and dimensions. This article contains supporting information that is available online.

Heat transfer enhancement by skewed wavy sidewall for two-pass ribbed channels with different aspect ratios

Thermal performances of the newly devised compound heat transfer enhancement (HTE) method by deploying the in-line 45° ribs and skewed waves along the two opposite pairs of channel endwalls and sidewalls, respectively, for three two-pass sharp-bend channels with aspect ratios (AR) of 0.5, 1 and 2 are studied. For each test channel at Reynolds number (Re) between 5000 and 20,000, the full-field Nusselt number (Nu) distributions over the ribbed endwall and the channel-averaged pressure drop coefficients (f) are measured to determine the thermal performance factors (TPF) as the efficiency indices for heat transmissions. A set of Nu, f and TPF data obtained from the three test channels is selected to illustrate the HTE properties and the associated f augmentations. With present orientations for the skewed sidewall waves and the 45° endwall ribs to trip the co-current axial swirls, the local and area-averaged endwall Nusselt numbers (Nu‾A) are considerably raised by elevating the HTE benefits over the mid-rib regions. The Nu‾A levels over the ribbed endwalls for present test channels with AR=0.5, 1 and 2 are respectively raised to 4.74–3.83, 6.25–4.94 and 7.43–6.09 times of the Dittus–Boelter references. With the accompanying f augmentations to 24.54–12.44, 17.35–10.42 and 26.71–19.82 times of the Blassius levels, the TPF values for present test channels of AR=0.5, 1 and 2 fall in the ranges of 1.74–1.62, 2.42–2.24 and 2.51–2.28 respectively. The averaged Nusselt number correlations over inlet/outlet legs, turning region and entire endwall, as well as the f correlations, for present test channels are generated to assist the design activities.

Numerical Study of Natural Convection within a Wavy Enclosure Using Meshfree Approach: Effect of Corner Heating

This paper presents a numerical study of natural convection within a wavy enclosure heated via corner heating. The considered enclosure is a square enclosure with left wavy side wall. The vertical wavy wall of the enclosure and both of the corner heaters are maintained at constant temperature, T c and T h, respectively, with T h > T c while the remaining horizontal, bottom, top and side walls are insulated. A penalty element-free Galerkin approach with reduced gauss integration scheme for penalty terms is used to solve momentum and energy equations over the complex domain with wide range of parameters, namely, Rayleigh number (Ra), Prandtl number (Pr), and range of heaters in the x- and y-direction. Numerical results are represented in terms of isotherms, streamlines, and Nusselt number. It is observed that the rate of heat transfer depends to a great extent on the Rayleigh number, Prandtl number, length of the corner heaters and the shape of the heat transfer surface. The consistent performance of the adopted numerical procedure is verified by comparison of the results obtained through the present meshless technique with those existing in the literature.