Wavy Wall Research Articles

Microscopic analysis of Valeriana stolonifera and Valeriana collina leaves

Plants of the Valeriana species are distributed in various parts of the world, especially in Europe and Asia. A high content of polyphenolic compounds, including flavonoids and hydroxycinnamic acids with expressed biological activity, was previously identified within the herb of the studied Valeriana species. Morphological and anatomical data can be used in phylogenetics of species and genera to find out diagnostic and age-related characteristics of plants. This led us to microscopic studies of aerial organs of the above-mentioned Valeriana species. The aim of the work is to conduct a comparative study of the diagnostic features within the morphological and anatomical structure of Valeriana stolonifera and Valeriana collina leaves. Materials and methods. Both raw and dried plant material of V. stolonifera and V. collina was used for microscopic studies. Temporary micropreparations were made using generally accepted methods. The anatomical features of the raw material were examined using Carl ZEISS “AxioStar Plus” and “Primo Star”. Results. The study identified key morphological and anatomical features of the species, which should be considered for the identification and standardization of promising medicinal plant materials and within the development of methods of analytical and regulatory documentation. Conclusions. The key microscopic differences in the leaves of the studied species lie in the structure of the adaxial and abaxial surfaces of the leaf blade. The upper epidermis consists of large elongate cells with wavy walls. The cells of the lower epidermis are smaller and have more sinuous walls compared to the upper epidermis cells. The degree of wall sinuosity varies between species – V. collina is characterized by more sinuous cells in both the upper and lower epidermis compared to V. stolonifera. The absence of stomata on the upper epidermis is a common feature for both species.

Thermal analysis of nonlinear mixed convection effects within wavy enclosure

The analysis in this study focusses on the transfer of heat within a wavy cavity in the presence of nonlinear mixed convection and MHD. We conduct the investigation under conditions where the upper wall of the cavity remains cold, the lower wall receives heat, and the left and right wavy walls remain adiabatic. Using the PDE solver in COMSOL, the non-dimensional system is simplified, employing the finite element method. The study aims to explore the impact of parameters such as nanoparticle concentration, Hartmann number, Reynolds number, Richardson number, and nonlinear mixed convection parameters on fluid flow and heat transfer. An artificial neural network has been employed to examine the behaviour of the Nusselt number within a cavity. The isotherms reveal that the temperature is higher near the lower wall for all parameters due to the heated source. Analysis of the streamline plots indicates that heat increases as it moves towards the upper wall, influenced by the Hartman number and volume fraction parameter. The use of ANN in the study forecasts the accuracy, smoothness, and convergence of the data through plots of mean squared error (MSE), error histogram, regression analysis, and transition state plot. The authors believe that using artificial neural networks to explore the heat transfer rate under the assumptions of MHD and nonlinear mixed convection is a novel approach that has not been previously investigated. Additionally, researchers can utilise ANN concepts to predict intricate cavity formations through multiphysics. This approach will require less human effort and computing time to analyse the heat response of any dataset.

Enhancement of heat transfer characteristics in wavy microchannel heat sinks with streamlined micropins within convergent-divergent flow passages

In the current study, the heat transfer characteristics of a novel design microchannel with a wavy sinusoidal convergent-divergent wall structure featuring streamlined pins have been numerically investigated under laminar flow conditions. Various amplitudes, wavelengths, pin heights, and Reynolds numbers are considered as parameters. The thermal and hydraulic characteristics are analyzed in terms of Nusselt number, Fanning friction factor, and Performance Evaluation Criteria number (PEC), which evaluates the heat transfer enhancement against the associated pressure drop. It is revealed that increasing the amplitude and decreasing wavelength, along with moderate pin heights, significantly augment heat transfer. The streamlined pins effectively direct the flow, and the resulting secondary flow and chaotic advection considerably enhance heat transfer in the designed configuration. The study demonstrates that the heat transfer can be improved by a factor of 4.79 compared to a straight microchannel. Under these geometric and flow conditions, the pressure drop increases by a factor of 9.87, and the PEC is found to be around 2.23. A multi-objective optimization study using the Non-dominated Sorting Genetic Algorithm (NSGA-II) is conducted with Genetic Aggregation Response Surface Methodology to evaluate the impact of various parameters on thermal-flow performance and to identify the optimal design with material quantity variation. According to the optimal results, a 5 % increase in material can augment thermal-flow performance by approximately 206.6 % compared to traditional microchannels. Finally, practical correlations for the Nusselt number and friction factor, accounting for various parameters, have been developed to facilitate in designing of microchannel cooling systems.

Azimuthally-distributed wavy inner wall treatment for high subsonic jet noise control

The noise generated by subsonic jet nozzles, commonly encountered in civilian aircraft, is rather significant and propagates in both the upstream and downstream directions due to large-scale and fine-scale turbulence structures. In this paper, a distinctive inner wall treatment strategy, denoted as the Azimuthally-distributed Wavy Inner Wall (AWIW), is proposed, which is aimed at mitigating jet noise. Within this strategy, a circumferentially dispersed treatment wall characterized by a minute wavy pattern is substituted for the smooth inner wall in proximity to the nozzle outlet. To assess the effectiveness of the AWIW treatment, we conducted numerical simulations. The unsteady flow field and far-field noise were predicted by employing Large Eddy Simulations (LES) coupled with the Ffowcs Williams and Hawkings (FW-H) integration method. To gain a comprehensive understanding of the mechanism underlying the noise reduction facilitated by the AWIW treatment, it examined physical parameters such as the Lighthill source acoustic source term, the turbulent kinetic energy acoustic source term, and the shear layer instability. The results reveal that the AWIW treatment expedites the instability within the shear layer of the jet, leading to an early disruption of the jet shear layer, and consequently turbulent structures in varying sizes are generated downstream. This process effectively regulates the generation and emission of jet noise. By controlling the minor scale turbulence through the AWIW treatment, the mid- and high-frequency noise within the distant field can be significantly reduced. In the context of the flow field, the introduction of AWIW also leads to a decrease in drag on the inner wall surface of the jet, thereby improving the overall aerodynamic performance of the nozzle. Considering these attributes, the AWIW strategy emerges as a viable technique for the reduction of jet noise.

Numerical investigation of the collision of a vortex pair upon a solid wavy wall

The vortex dynamics produced by the collision of a vortex pair with a solid wavy wall are examined numerically using a proposed high-order vortex particle method. The influences of the Reynolds number (ReΓ) of the vortex pair, the wavelength (λw), and the wave amplitude (Aw) of the wall on the induced vortex structures, interactions among vortices, and the instability and reconnection of secondary vortices are discussed. The boundary layers at the top of ripples separate first to form the secondary vortices moving around the primary tubes. Meanwhile, the boundary layers at the bottom of ripples detach late, move vertically upward, and then form incomplete vortex loops due to an unsuccessful reconnection of the secondary vortices. The ReΓ effects cause the appearance of various vortex structures, such as incomplete primary vortex loops from the bottom of ripples at ReΓ=1000, secondary vortex loops due to interactions of the first loops with the wall at ReΓ=2000, and hairpin vortices at ReΓ=4000. The wavelength of the wall induces instability in the secondary vortex tubes. This instability on the secondary tubes appears at the top of ripples at λw=2r0, while it spreads over the whole secondary vortices at λw=4r0, where r0 is the initial spacing between the primary vortex tubes. This instability results in various wavy tubes that robustly interact with the primary tubes. Due to the effects of Aw, the primary vortex tubes significantly decay with time compared to those in the flat wall case.

A computational study of the influence of wavy arteries and veins on hemodynamic characteristics in an unsteady state

The present work is focused on the study of hemodynamic characteristics for tortuous arteries/veins in a pulsatile flow. This work is an extension of an earlier work by the author, which reported the hemodynamic characteristics in a steady flow situation. It is a well-known fact that various geometric parameters affect the hemodynamics, such as the diameter of vessels, the diameter of mother and daughter tubes in bifurcation, the angle between them, and their relative magnitudes. This paper is focused on the effect of tortuosity produced in straight and bifurcating tubes under pulsatile flow conditions. A heartbeat rate of 120 bpm is considered for pulsation, covering one cycle of systole and diastole. The measure of tortuosity is defined by the varying pitch and the amplitude. The present analysis is carried out computationally using ANSYS. Results are presented through secondary flow streamline, velocity profile, and its effect on wall shear stress. Key findings are that secondary vortices are observed in the bifurcated model and counter-rotating vortices are observed in the wavy tube geometry. The velocity distribution is asymmetric in the case of the plain bifurcation geometry. In the case of the wavy tube and bifurcated geometry, there is a shift in peak velocity from the inner to the outer wall, depending on the crest and trough positions of the tortuous vein. Relative change in magnitude of velocity for wavy tube depends on the depth and pitch of wavy wall of the tortuous tube. The velocity reduces with an increase in time step for unsteady flow.

The effect of initial pressure and temperature on the flow in a three-dimensional cavity filled with paraffin/Cu nanostructure with a wavy lower wall and a movable upper wall using molecular dynamics simulation

Phase change materials (PCMs) are very suitable for the storage of thermal energy. Heat transfer plays a crucial role in many important industrial processes in today's industrial environment. Thus, it is crucial to examine and comprehend this occurrence properly. This work uses molecular dynamic simulation to examine the effect of initial pressure (IP) and temperature (Temp) on the thermal efficiency of phase change materials inside a three-dimensional cavity. The hollow contains paraffin/Cu nanoparticles and has a bottom wall with a wavy shape and an upper wall that can be adjusted. The results of the equilibration stage indicated that the kinetic and potential energies converge to 2100 eV and -95472.50 eV after 10 ns. Next, the results show that increasing IP resulted in the reduction of maximum velocity and Temp, which decreased from 0.0099 Å/ps and 898 K to 0.0090 Å/ps and 888 K. Furthermore, the results show that by increasing IP, the heat flux and thermal conductivity decrease from 9.95 W/m2 and 1.45 W/m.K to 8.89 W/m2 and 1.26 W/m.K. Conversely, as the initial Temp rose from 300 to 350 K, so did the velocity (0.0125 Å/ps) and Temp (990 K). Furthermore, the thermal conductivity and heat flux increased to 1.69 W/mK and 11.25 W/m2, respectively. This study reveals how molecular dynamics simulations provide insights into the effects of initial pressure and temperature on the flow and thermal behavior of a paraffin/copper nanostructure. The findings improve understanding of nanofluid and phase change material behavior, aiding the design of more efficient PCM-based systems for thermal energy storage and heat transfer applications. In general, the results of this research illuminate the complex relationship among IP, Temp, and thermal properties of phase change materials. This knowledge is of great significance as it can guide the formulation of novel approaches to enhance the thermal efficiency of these materials in practical applications.

Impact of Heated Wavy Wall and Hybrid Nanofluid on Natural Convection in a Triangular Enclosure with Embedded Cold Cylinder under Inclined Magnetic Field

Impact of Heated Wavy Wall and Hybrid Nanofluid on Natural Convection in a Triangular Enclosure with Embedded Cold Cylinder under Inclined Magnetic Field

Numerical investigation of free convection inside square wavy enclosure using response surface methodology

AbstractFree convection is commonly applied in various engineering fields such as solar energy, electronic devices, nuclear energy, and heat exchangers. A computational simulation was used to analyze the natural heat transfer through convection in a wavy cavity with squared shape that was filled with tap water and saturated metal foam to assess the influence of hump configuration (square, triangle, circular, down semicircular, and up semicircular) and magnetic fields (magnetohydrodynamics) on heat transfer rate. The bottom wavy wall of the enclosure exhibits a high temperature (Th), whereas the top and side walls maintain a low temperature (Tc). The present paper will examine how the bottom wall hump number (N), aspect ratio (L), geometry inclination angle (θ), Hartman number (Ha), magnetic field intensity inclination angle (ɤ) affects the heat transfer rate at various Rayleigh numbers. When the circular hump design is used with specific parameters, including ɛ = 0.85, L = 1.25, N = 4, Tc = 0°C, θ = 0°, Ha = 600 and ɤ = 45°, for different Ra values, it leads to increased heat transfer and notable improvements in heat transfer enhancement (ɸ) and energy enhancement (e). The enhancements were measured at 2.5 times for heat transfer enhancement and 8.9 times for energy enhancement. Moreover, the ideal case of the current study had Ha = 600, L = 1.25, Ra = 30 × 103, and θ = 0° compared to the baseline case. Simulations were accomplished using CFD. The results demonstrate that the primary goal of the research was achieved by optimizing the design, leading to a significant improvement in hydrothermal performance for both ɸ = 2.5 and e = 8.9.

Heat transfer analysis of nanofluid flow with entropy generation in a corrugated heat exchanger channel partially filled with porous medium

AbstractHeat exchanger research is mainly exploited to develop and optimize new engineering systems with high thermal efficiency. Passive methods based on nanofluids, fins, wavy walls, and the porous medium are the most attractive ways to achieve this goal. This investigation focuses on heat transfer and entropy production in a nanofluid laminar flow inside a plate corrugated channel (PCC). The channel geometry comprises three sections, partially filled with a porous layer located at the intermediate corrugate channel section. The physical modeling is based on the laminar, two‐dimensional Darcy–Brinkman–Forchheimer formulation for nanofluid flow and the local thermal equilibrium model for the heat equation, including the viscous dissipation term. Numerical solutions were obtained using ANSYS Fluent software based on the finite volume technique and the appropriate meshed geometries. The numerical results are validated with theoretical, numerical, and experimental studies. The simulations are performed for CuO–water nanofluid and AISI 304 porous medium. The coupled effects of porous layer thickness (δ), Reynolds number (Re), and nanoparticle fraction (φ) on velocity, streamlines, isotherm contours, Nusselt number (Nu), and entropy generation (S) are analyzed and illustrated. The simulation results demonstrate that heat transfer enhancement in clear PCC can be achieved using a porous layer insert. For the porous thickness range of [0.1–0.6], the corresponding range of average Nusselt number increase is [35.7%–176.9%], and the average entropy generation is [105.4%–771.9%]. The effect of the Reynolds number is more important in a porous duct than in a clear one. For δ = 0.4 and φ = 5%, the increase of Re in the range of [200–500] induces an increase in average Nusselt number in the range of [80.9%–108.4%] and average entropy in [222.9%–309.1%] comparatively to clear PCC. The effect of φ is practically the same for porous and clear channels. For φ = 5%, the increase on average Nu is about 9%, and entropy generation is 5%. Accordingly, important improvements in heat transfer in PCC can be achieved through the combined effect of flow Reynolds number and porous layer thickness.

Investigation of the unsteady MHD fluid flow and heat transfer through the porous medium asymmetric wavy channel

This paper uses three analytical methods to find the novel results in the two-dimensional time-dependent MHD oscillatory flow and heat transfer in an asymmetric wavy porous channel. The corresponding constitutive equations become complex by considering the pressure gradient as a complex function. This results in the existence of both real and imaginary solutions for fluid velocity and temperature. The changes in parameters like the Hartmann number, wavelength, Grashof number, and porous medium shape factor will affect the real fluid velocity. Still, only radiation parameter changes will affect the real fluid velocity and temperature. Increasing the Hartmann number, porous medium shape factor, and radiation parameter will drastically reduce real fluid velocity. The Reynolds number should theoretically affect the imaginary velocity, but according to the boundary condition definition, the imaginary velocity value becomes zero. Altering the frequency of the wavy walls and the Peclet number will only affect the imaginary temperature component, and increasing these parameters will increase the average imaginary temperature profile. The uniqueness of this study lies in the resolution of complex differential equations in a way that has not been attempted before. The results indicated that each set of three solutions was nearly identical, highlighting the outcomes' precision.

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.

Thermoviscous dissipation of nonlinear acoustic waves in channels with wavy walls.

We derive a nonlinear acoustic wave propagation model for analyzing the thermoviscous dissipation of nonlinear acoustic waves in narrow pores with wavy walls using the boundary layer theory. As a nonlinear acoustic wave propagates in a pore, the wave-steepening effect competes with the bulk dissipation, as well as the thermoviscous heat transfer and shear from the pore walls. Due to thermoviscous dissipation, the wave thickness increases beyond the weak shock thickness scale. Using the weak shock thickness scale, we obtain dimensionless linear and nonlinear model wave equations governing the shock-wall interactions. We also perform two-dimensional shock-resolved direct numerical simulation of the wave propagation inside the pores and compare the results with model equations. The direct numerical simulation and model calculations show that, for flat walls and shock strength parameter ϵ, the dimensional wall heat-flux and shear scale as ϵ. For wavy walls, the scaling becomes ϵ3/2-n(k) where k is the wall-waviness wavenumber and the exponent n increases from 0.5 for k = 0 to n(k)≈0.65 for k = 10, n(k)≈0.75 for k = 20, and n(k)≈0.85 for k = 40. Furthermore, we show that both the dimensionless scaled wall shear and wall heat-flux decrease with increasing k.

Hydrodynamic Impact of Dusty Fluid-Suspended Solid Particles in a Single-Walled Corrugated Channel for Water-Curing Infrastructure Networks

Infrastructure engineering is impacted by solid particles in fluids, and engineering components are influenced by fluid flow methods. This work explores the effects of dusty fluids with suspended solid particles in a single-walled corrugated channel using electromagnetic hydrodynamics. Potential, continuity, and momentum equations were employed to study the periodic sinusoidal waves in the corrugations of two wavy walls using the perturbation method. We assessed the impact of corrugation on velocity for EMHD fluid flow using mathematical computation, concentrating on the analytical velocity solutions. The analysis of velocity profiles through graphs reveals that corrugation affects fluid and particle velocity behavior, with small amplitude reducing wave effects and dusty particles boosting velocity. The proposed model uses mathematical induction to solve engineering problems using corrugated wall conditions for fluid control during curing stages. It may be valuable for sanitation networks, rainwater drainage networks, and irrigation systems. In the end, a thorough examination of the obtained results and information from past papers demonstrated a high level of agreement. Additionally, its use in the curing of water will offer alternative methods of managing the flowing fluid than mechanical pressure.

Hydrodynamic instability of shear imposed falling film over a uniformly heated inclined undulated substrate

Linear and weakly nonlinear stability analyses of an externally shear-imposed, gravity-driven falling film over a uniformly heated wavy substrate are studied. The longwave asymptotic expansion technique is utilized to formulate a single nonlinear free surface deflection equation. The linear stability criteria for the onset of instability are derived using the normal mode form in the linearized portion of the surface deformation equation. Linear stability theory reveals that the flow-directed sturdy external shear grows the surface wave instability by increasing the net driving force. On the contrary, the upstream-directed imposed shear may reduce the surface mode instability by restricting the gravity-driving force, which has the consequence of weakening the bulk velocity of the liquid film. However, the surface mode can be stabilized/destabilized by increasing the temperature-dependent density/surface-tension variation. Furthermore, the bottom steepness shows dual behavior on the surface instability depending upon the wavy wall's portion (uphill/downhill). At the downhill portion, the surface wave becomes more unstable than at the bottom substrate's uphill portion. Moreover, the multi-scale method is incorporated to obtain the complex Ginzburg–Landau equation in order to study the weakly nonlinear stability, confirming the existence of various flow regions of the liquid film. At any bottom portion (uphill/downhill), the flow-directed external shear expands the supercritical stable zones, which causes an amplification in the nonlinear wave amplitude, and the backflow-directed shear plays a counterproductive role. On the other hand, the supercritical stable region decreases or increases as long as the linear variation of density or surface tension increases with respect to the temperature, whereas the sub-critical unstable region exhibits an inverse trend.

Investigation of heat transfer enhancement and thermal stratification phenomenon on supercritical hydrogen fuel flow

Thermal stratification is one of the major issues in rectangular regenerative cooling channels because of the asymmetric heating and limited turbulent diffusion of thermal energy of the fuel. As a result, the heat transfer performance is decreased. This paper uses Ansys fluent software to construct a novel cooling structure that combines wavy wall surfaces with cylindrical fins. In addition to this new configuration, this study also examined three other configurations (straight-smooth, cylindrical-ribs, and wavy-smooth) and compared them with each other. This structure aims to efficiently enhance hydrogen coolant flow and heat transfer characteristics while reducing the extent of the non-uniform distribution issue. The results show that the new structure’s Nusselt number and maximum wall temperature are enhanced by 46.89% and 22.71%, respectively, compared to the straight-smooth structure; in contrast, the friction factor increased only by 3.64% over the smooth channel. The novel design has the best thermal performance factor compared to the other three designs, which is improved by 43.33% over the smooth channel. Among all configurations, the new structure is the best fluid temperature distribution configuration, which shows an optimal distribution of the coolant temperatures between layers; thus, the stratification phenomena decreased significantly.

Flow-induced noise and vibration in axial fan: a case study

AbstractReducing axial fan noise is crucial in residential, commercial, and industrial applications. This study explores how attaching different add-on designs to axial fans reduces aerodynamic noise. Eight design cases were examined, including extending the outlet and inlet ducts, using Chevron nozzles, placing internal spherical balls in staggered and straight patterns, applying a wavy inner wall treatment, and combining some of these nozzle designs. CFD and acoustic analyses were performed using Ansys Fluent 2022 R1. Noise reduction was measured at the nozzle outlet in each design case. All nozzle modifications reduced noise levels, with noise reductions ranging from 3 to 10% at the blade tip and 26–55% at the outlet. As an add-on to existing fan cases, the design cases investigated in this study can potentially improve the acoustic environment in various settings. The findings of this study can contribute to the development of quieter axial fans.

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 ° .

The impact of wedge and wavy-wall combustor side walls on shock-induced mixing and combustion in a hydrogen-fuelled model scramjet combustor

The mixing and combustion processes are linked and challenging for a supersonic combustion engine. Supersonic air doesn't spend much time in the combustor, making it challenging to blend fuel with supersonic air. The expansion of shear-mixing layer with shock waves and their interactions are the primary characteristics of mixing augmentation. This paper investigates the same methodology for a model scramjet combustion chamber with wedge and wavy sides. The novel scramjet combustion models include wedge and way-wall sidewalls based on the basic scramjet model. By combining the finite volume approach with a second-order upwind discretization method, the Reynolds-averaged Navier-Stokes equations are numerically analyzed. The interplay between wedge and wavy-wall effects and free stream flows is taken into consideration by using the shear stress transport (SST) k−ω turbulence model. The effect of the wedge and wavy wall combustor has been evaluated by analysing the shock production and their interactions with the mixing layer and internal flow structure. The turbulence characteristics are also examined to analyse the degree of flow disturbance for wedge and wavy-wall combustion. The wavy wall combustor model results in a 14.5% increase in turbulence intensity, which raises air-fuel mixing and there by improves mixing and combustion efficiency by 12.59% and 11.23%, compared to the base wedge type combustor.

Evaluation of wavy wall configurations for accelerated heat recovery in triplex-tube energy storage units for building heating applications

Efficient thermal energy storage (TES) is crucial for integrating intermittent renewable energy sources and managing fluctuations in energy supply and demand. Among TES methods, latent heat TES (LHTES) using phase change materials (PCMs) is highly promising due to its high energy storage density and nearly isothermal operation during phase transitions. However, the inherently low thermal conductivity of PCMs hinders heat transfer rates, negatively impacting charging and discharging performance. This study investigates novel wavy channel geometries for the PCM container in a triplex-tube LHTES unit to enhance heat transfer and improve solidification rates during the discharge process. A comprehensive computational model based on the enthalpy-porosity method is developed to simulate the PCM (paraffin wax RT35) solidification inside wavy channels with sinusoidal, zigzag, and step-function profiles. The effects of channel geometry, heat transfer fluid (HTF) velocity, and inlet temperature on solidification rate and heat recovery are systematically evaluated. Results demonstrate that the step-function geometry significantly accelerates solidification compared to straight channels, reducing discharge time by 65.1 % and increasing heat recovery rate by 147.9 %. Decreasing waviness width from 15 mm to 5 mm further reduces solidification time by 70.1 %, while increasing waviness height from 5 mm to 15 mm leads to a 74.4 % reduction. Moreover, increasing HTF flow from Re = 250 to 1000 enhances heat recovery by 92.3 %, and lowering inlet temperature from 20 °C to 10 °C improves it by 76.9 %. The findings provide valuable insights for designing efficient LHTES units with wavy channel geometries for renewable energy integration and thermal management applications.