Search results

To improve the thermal performance of base fluid, nanoparticles of three types are dispersed in the base fluid. A novel theory of non-Fourier heat transfer is used for design and development of models. The thermal performance of sample fluids is compared to determine which types of combination of nanoparticles are the best for an optimized enhancement in thermal performance of fluids. This article aims to: (i) investigate the impact of nanoparticles on thermal performance; and (ii) implement the Galerkin finite element method (GFEM) to thermal problems.

The mathematical models are developed using novel non-Fourier heat flux theory, conservation laws of computational fluid dynamics (CFD) and no-slip thermal boundary conditions. The models are approximated using thermal boundary layer approximations, and transformed models are solved numerically using GFEM. A grid-sensitivity test is performed. The accuracy, correction and stability of solutions is ensured. The numerical method adopted for the calculations is validated with published data. Quantities of engineering interest, i.e. wall shear stress, wall mass flow rate and wall heat flux, are calculated and examined versus emerging rheological parameters and thermal relaxation time.

The thermal relaxation time measures the ability of a fluid to restore its original thermal state, called thermal equilibrium and therefore, simulations have shown that the thermal relaxation time associated with a mono nanofluid has the most substantial effect on the temperature of fluid, whereas a ternary nanofluid has the smallest thermal relaxation time. A ternary nanofluid has a wider thermal boundary thickness in comparison with base and di- and mono nanofluids. The wall heat flux (in the case of the ternary nanofluids) has the most significant value compared with the wall shear stresses for the mono and hybrid nanofluids. The wall heat and mass fluxes have the highest values for the case of non-Fourier heat and mass diffusion compared to the case of Fourier heat and mass transfer.

An extensive literature review reveals that no study has considered thermal and concentration memory effects on transport mechanisms in fluids of cross-rheological liquid using novel theory of heat and mass [presented by Cattaneo (Cattaneo, 1958) and Christov (Christov, 2009)] so far. Moreover, the finite element method for coupled and nonlinear CFD problems has not been implemented so far. To the best of the authors’ knowledge for the first time, the dynamics of wall heat flow rate and mass flow rate under simultaneous effects of thermal and solute relaxation times, Ohmic dissipation and first-order chemical reactions are studied.

This study aims to develop a methodology that extracts an architectural concept from a biological analogy that integrates forms and kinetic behavior to identify whether complex forms work better or simple forms with proper kinetic behavior for improving visual comfort and daylight performance.

The research employs a transdisciplinary approach using several methods consisting of a biomimetic functional-morphological approach, kinetic design strategy, case study comparison using algorithmic workflow and parametric simulation and inverse design, to develop an interactive kinetic façade with optimized daylight performance.

A key development is the introduction of a periodic interactive region (PIR), which draws inspiration from the butterfly wings' nanostructure. These findings challenge conventional perspectives on façade complexity, highlighting the efficacy of simpler shapes paired with appropriate kinetic behavior for improving visual comfort. The results show the façade with a simpler “Bookshelf” shape integrated with a tapered shape of the periodic interactive region, outperforms its more complex counterpart (Hyperbolic Paraboloid component) in terms of daylight performance and glare control, especially in southern orientations, ensuring occupant visual comfort by keeping cases in the imperceptible range while also delivering sufficient average spatial Daylight Autonomy of 89.07%, Useful Daylight Illuminance of 94.53% and Exceeded Useful Daylight Illuminance of 5.11%.

The investigation of kinetic façade studies reveals that precedent literature mostly focused on engineering and building physics aspects, leaving the architectural aspect underutilized during the development phase. Recent studies applied a biomimetic approach for involving the architectural elements besides the other aspects. While the biomimetic method has proven effective in meeting occupants' visual comfort needs, its emphasis has been primarily on the complex form which is difficult to apply within the kinetic façade development. This study can address two gaps: (1) the lack of an architectural aspect in the kinetic façade design specifically in the development of conceptual form and kinetic behavior dimensions and (2) exchanging the superficial biomimetic considerations with an in-depth investigation.

In order to include the non-negligible lag relaxation time feature that is characteristic of heat transfer in biological bodies, the classical Fourier's law of heat conduction has to be generalized as the Maxwell–Cattaneo law resulting in the thermal-wave model of bio-heat transfer. The purpose of the paper is to retrieve the unknown time-dependent blood perfusion coefficient in such a thermal-wave model of bio-heat transfer from (non-intrusive) measurements of the temperature on an accessible sub-portion of the boundary that may be taken with an infrared scanner.

The nonlinear and ill-posed problem is reformulated as a nonlinear minimization problem of a Tikhonov regularization functional subject to lower and upper simple bounds on the unknown coefficient. For the numerical discretization, an unconditionally stable direct solver based on the Crank–Nicolson finite-difference scheme is developed. The Tikhonov regularization functional is minimized iteratively by the built-in routine lsqnonlin from the MATLAB optimization toolbox. Numerical results for a benchmark test example are presented and thoroughly discussed, shedding light on the performance and effectiveness of the proposed methodology.

The inverse problem of obtaining the time-dependent blood perfusion coefficient and the temperature in the thermal-wave model of bio-heat transfer from extra boundary temperature measurement has been solved. In particular, the uniqueness of the solution to this inverse problem has been established. Furthermore, our proposed computational method demonstrated successful attainment of the perfusion coefficient and temperature, even when dealing with noisy data.

The originalities of the present paper are to account for such a more representative thermal-wave model of heat transfer in biological bodies and to investigate the possibility of determining its time-dependent blood perfusion coefficient from non-intrusive boundary temperature measurements.

The investigation concentrated on studying a distinct category of tubular heat exchanger that uses swirling airflow over tube bundle maintained at constant heat flux. Swirl flow is achieved using a novel perforated baffle plate with rectangular openings and multiple adjustable opposite-oriented saw-tooth flow deflectors. These deflectors were strategically placed at the inlet of the heat exchanger to create a swirling flow downstream.

The custom-built axial flow heat exchanger consists of three baffle plates arranged longitudinally supporting tube bundle maintained at constant heat flux. The baffle plate equipped with saw-tooth flow deflector of various geometry represented by space height ratio(e/h). Next, ambient air was then directed over the tube bundle at varying Reynolds number and the effect of baffle spacing (PR), Space height ratio (e/h) and inclination angle(a) of deflectors on performance of heat exchanger was experimentally analyzed.

The heat transfer augmentation of heat exchanger for given operating condition is strongly dependent on geometry, inclination angle of deflector and baffle spacing.

An average improvement of 1.42 times in thermal enhancement factor was observed with inclination angle of 30°, space height ratio of 0.4 and a pitch ratio of 1.2 when compared to a heat exchanger without a baffle plate under similar operating conditions.

This study aims to understand the effect of the use of different proportions and types of fibers in the polyamide 6 (PA6) matrix during material extrusion-based additive manufacturing (MEX) and the effect of the manufacturing parameters on the mechanical properties. The mechanical, thermal and morphological properties of PA composites that are reinforced with carbon fiber (CF), glass fiber (GF) and as well as hybrid fiber (HF) were investigated.

In this study, the effect of nozzle temperature and layer thickness on the mechanical properties of composite samples was investigated in terms of their behavior under tensile, impact and compression loads, manufacturing parameters as well as fiber ratio and type. The results were also consolidated by scanning electron microscopy.

At 20 Wt.% CF reinforcement PA6 samples, a tensile strength value of 125 MPa was obtained with a 60% increase in tensile strength value compared to neatPA6. The HF-reinforced ones also measured a tensile strength value of 106.69 MPa. This corresponds to an increase of 38% compared to neatPA6. The results also show that HF reinforcement can be an important component for many composites and a suitable material for use under compression loading.

PA6, an engineering polymer, can be produced by MEX, which offers several advantages for complex geometries and customized designs. There are studies on different carbon and GF ratios in the PA6 matrix. Using these fibers together in a HF, the examination of their mechanical properties in the MEX method and the examination of the effect of GF reinforcement in the hybrid structure, which has a cost-reducing effect, has been an innovative approach. In this study, the results of the optimization of the parameters affecting the mechanical properties in the production of samples reinforced with different ratios and types of fibers in the PA6 matrix by the MEX method are presented.

This study aims to support the global initiatives that advocate for ensuring healthy lives and promoting well-being for everyone, regardless of age, while allowing people to stay at their homes as long as they desire. The built environment (BE) plays a crucial role in achieving this, but in some countries, such as the UK, the housing stock has been found to require extensive adaptations to support resident’s health and well-being. While much research has been done on care provisions and later living housing, these solutions are unsuitable for low-population density areas (LPDAs).

The study is encompassed by investigations around a systematic product development guided by the Double-Diamond Design Framework. This research focused on the “Discovery” phase, which involved online in-depth interviews, incorporating elements from the Human-Activity-Space-Technology Model, supplemented by an interactive board to discover key activities, elements and actors involved in supporting strategies for ageing in place.

This paper presents strategies to help people age in place, focusing on LPDAs. The interventions identified in this paper encompass fundamental elements such as layout design and smart home technologies.

The results provide contextualised BE interventions applicable to creating age-friendly communities, focusing on house design and service delivery from a product design approach.

The purpose of the paper is to analyse the performances of closures and compressibility corrections classically used in turbulence models when applied to highly-compressible turbulent boundary layers (TBLs) over flat plates.

A direct numerical simulation (DNS) database of TBLs, covering a wide range of thermodynamic conditions, is presented and exploited to perform a priori analyses of classical and recent closures for turbulent models. The results are systematically compared to the “exact” terms computed from DNS.

The few compressibility corrections available in the literature are not found to capture DNS data much better than the uncorrected original models, especially at the highest Mach numbers. Turbulent mass and heat fluxes are shown not to follow the classical gradient diffusion model, which was shown instead to provide acceptable results for modelling the vibrational turbulent heat flux.

The main originality of the present paper resides in the DNS database on which the a priori tests are conducted. The database contains some high-enthalpy simulations at large Mach numbers, allowing to test the performances of the turbulence models in the presence of both chemical dissociation and vibrational relaxation processes.

The influence of the temperature discrepancy parameter and higher order of the time-derivative is discussed. Classical coupled and generalized hygrothermoelasticity models are recovered by considering the various special cases and illustrated graphically.

The theory of integral transformations has been used to study a new hygrothermal model that includes higher-order time derivatives with three-phase-lags and memory-dependent derivatives (MDD). This model considers the microscopic structure’s influence on a non-simple hygrothermoelastic infinitely long cylinder. The generalized Fourier and Fick’s law was adopted to derive the linearly coupled partial differential equations with higher-order time-differential with the two-phase lag model, including memory-dependent derivatives for the hygrothermal field. The investigation of microstructural interactions and the subsequent hygrothermal change has been undertaken as a result of the delay time and relaxation time translations.

These two-phase-lag models are also practically applicable in modeling nanoscale heat and moisture transport problems applied to almost all important devices. This work will enable future investigators to gain insight into non-simple hygrothermoelasticity with different phase delays of higher order in detail.

To the best of my knowledge, and after completing an intensive search of the relevant literature, the author could not learn any published research that presents a general solution for a higher-order time-fractional three-phase-lag hygrothermoelastic infinite circular cylinder with memory memory-dependent derivative.

The recent convergence between architecture and cultural anthropology has laid the foundations for a methodological approach that is attentive to both local specificities and the role of design. Starting from the analysis of the recovery of the primary school in the Bedouin camp of Wadi Abu Hindi in Palestine, the article intends to outline the role of the architect as a participating observer. It highlights how acting directly in the context of intervention guarantees a more effective response to local needs within spaces marked by strong conditions of inequality and marginality.

The methodology employed consists in using the ethnographic approach to collect qualitative data. The choice of this methodology stems from the intention to directly involve local actors in the design and execution phases.

The role of the architect as a participating observer within critical contexts shows how the activity of design is not simply limited to designing solutions but consists above all in the anticipation of all the critical aspects that may emerge in the practical execution of the works. The active participation and the adoption of a holistic outlook allow to find targeted solutions and ensure careful listening to the local needs.

The originality of this article consists in using an interdisciplinary approach between architecture and cultural anthropology, considering the architect as a participant observer.

This study aims to explore the role of sustainable fashion knowledge in shaping individual sustainable responsibility within the dynamic landscape of the fashion industry from a novel perspective, by exploring the intricate interplay between sustainable fashion knowledge, emotional and spiritual sustainable capacities.

A quantitative study was used, and a causal model with partial least squares structural equation modeling was developed. A total of 211 valid responses were obtained, and data were analysed to confirm the proposed hypotheses.

The findings confirm the positive impact of sustainable fashion knowledge on individual sustainable responsibility, mediated by both spiritual and emotional sustainable capacities. This study underscores the significance of individuals in influencing societal norms, prompting fashion companies to adopt sustainable practices.

The proposed conceptual framework integrates insights from the emotional and spiritual knowledge dynamics. This study uncovers the pathways through which individuals contribute to a more sustainable society.

The study not only advances the understanding of sustainable fashion practices but also provides actionable insights for policymakers, businesses and individuals seeking to foster a culture of sustainability in the fashion ecosystem.