Article
Green & Sustainable Science & Technology
Jamal-Eddine Salhi, Abdel-illah Amrani, Elmiloud Chaabelasri, Ahmed Alami Merrouni, Nassreddine Hmidi, Ali Lamrani Alaoui, Tarik Zarrouk, Merzouki Salhi, Najim Salhi
Summary: Artificial roughness in the form of repeated ribs on a surface improves heat transfer rate. A numerical study on heat transfer characteristics and flow structure of turbulent flow in a rectangular duct with repeated transverse rib roughness was conducted. The results show the relative evolution of the Nusselt number and indicate significant thermal performance improvement in cases (3) and (4).
ENERGY ECOLOGY AND ENVIRONMENT
(2023)
Article
Energy & Fuels
Pallavi Rastogi, Shripad P. Mahulikar
Summary: This study reveals a linear relationship between the Poiseuille number and the dimensionless entropy generation rate due to fluid friction in the hydrodynamically developing region. It is theoretically proven that the Poiseuille number is a direct measure of entropy generation caused by fluid friction.
JOURNAL OF ENERGY RESOURCES TECHNOLOGY-TRANSACTIONS OF THE ASME
(2022)
Article
Nuclear Science & Technology
Maolong Liu, Xiaowen Wang, Song Ni, Limin Liu, Hanyang Gu
Summary: This study investigates the impact of surface roughness on the friction pressure drop factor of fuel assembly by calculating the friction pressure drop factor. Two new friction factor correlations are proposed and validated for different flow regimes, providing important implications for the design and safety analysis of light water reactors.
ANNALS OF NUCLEAR ENERGY
(2022)
Article
Biochemical Research Methods
Federica Torrisi, Giovanna Stella, Francesca M. Guarino, Maide Bucolo
Summary: This paper presents a combination of a cell counting algorithm and a velocity algorithm based on a Digital Particle Image Velocimetry (DPIV) method to study the collective behavior of micro-particles in response to hydrodynamic stimuli. A wide experimental campaign was conducted using micro-particles of different natures and diameters, such as living cells and silica beads. The proposed data analysis procedure based on the DPIV-based algorithm and a custom counting algorithm allows for the extrapolation of micro-particles velocities and the obtainment of the instantaneous micro-particles number.
Article
Energy & Fuels
Issa F. Almesri, Mosab A. Alrahmani, Jaber H. Almutairi, Hosny Z. Abou-Ziyan
Summary: This paper proposes correlation equations for heat transfer and pressure drop in tunnel kilns with lattice brick settings. The developed equations consider previously uninvestigated parameters and extend the Reynolds numbers to a practical range. The achieved correlations are well compared with available ones and show that Nusselt numbers increase with Reynolds number and slightly with Prandtl number. The spacing and roughness of bricks also affect the Nusselt numbers and friction factors, while voidage fraction has a monotonic effect on both.
Article
Thermodynamics
Amit Kumar, Ajeet Pratap Singh, Akshayveer, O. P. Singh
Summary: A novel design of counter flow curved double-pass solar air heater (DPSAH) is proposed and validated in this paper. Numerical investigations show that it has better thermal performance compared to other designs, with a maximum augmentation of 23%. New correlations for Nusselt number (Nu) and friction factor (f) are developed for predicting the performance of the best design.
Article
Thermodynamics
Sanjeev Kumar, Randip Kumar Das, Kishor Kulkarni
Summary: This study investigates the heat transfer and fluid flow characteristics of a SAH duct with transverse ribs of different cross-sections using experimental and numerical methods. The results show that the semi-circular ribs have the highest Nusselt number, while the forward oriented symmetric half NACA 0020 ribs have the lowest friction factor. The highest thermo-hydraulic performance is achieved when using the reverse oriented symmetric half NACA 0020 ribs. Contour plots provide important insights into the physical phenomena inside the SAH. The numerical results are validated with experimental data.
CASE STUDIES IN THERMAL ENGINEERING
(2022)
Article
Chemistry, Multidisciplinary
Hawa Ringkai, Khairul Fikri Tamrin, Nadeem Ahmed Sheikh, Shahrol Mohamaddan
Summary: This study investigates the behaviors of water-in-oil droplets in an offset T-junction microchannel with different radii using micro-PIV software. The results show that increasing the radius of the microchannel leads to an increase in cross-sectional area and a decrease in the velocity of the water phase, with experimental velocities of the water droplets closely matching theoretical values.
APPLIED SCIENCES-BASEL
(2021)
Article
Thermodynamics
A. Ali Rabienataj Darzi, Mohamad Abuzadeh, Mohamad Omidi
Summary: This study numerically investigates the efficiency of using helical-coiled tubes with corrugated walls. It explores the impact of Reynolds number, tube diameter, corrugated height, and pitch on heat transfer and pressure drop, and found that higher corrugated height and lower corrugated pitch enhance heat transfer with increased friction factor. Additionally, a Nusselt number correlation is developed based on numerical results, showing a stronger dependence on corrugated height compared to corrugated pitch.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2021)
Article
Chemistry, Multidisciplinary
Waldemar Wodziak, Jacek Sobczyk
Summary: This study presents the characteristics of turbulent airflow in a channel with a single ribbed wall using PIV measurements. The study found the presence of two vortex structures between the ribs.
APPLIED SCIENCES-BASEL
(2022)
Article
Thermodynamics
Sachin Sharma, Randip Kumar Das, Kishor Kulkarni
Summary: This study compared the effects of six different baffles on the heat transfer and friction factors of a solar air heater, with the sine wave baffle shape found to perform the best within a certain range of operating and geometric parameters.
CASE STUDIES IN THERMAL ENGINEERING
(2021)
Article
Thermodynamics
Lingjian Kong, Guangzhe Liu
Summary: The experimental study found that the pressure drop of the spiral microchannel increases with increasing spiral diameter and aspect ratio, but decreases with spiral pitch and hydrodynamic diameter. The friction factor of the spiral microchannel is higher than that of the straight channel, and its value increases with the increase in curvature of the microchannel.
ADVANCES IN MECHANICAL ENGINEERING
(2022)
Article
Engineering, Civil
L. Robin Andersson, I. A. Sofia Larsson, J. Gunnar Hellstrom, Anton J. Burman, Patrik Andreasson
Summary: This study investigates high Reynolds number flow inside a channel with a rectangular cross-section to simulate tunnel conditions, finding that flow-roughness effects deviate from standard non-asymmetric channel flow and cannot be predicted accurately using current turbulence models.
JOURNAL OF HYDRAULIC RESEARCH
(2021)
Article
Thermodynamics
Arun K. Raj, C. N. Vinay, M. Srinivas, S. Jayaraj
Summary: This study investigates the impact of different combinations of roughness elements on heat dissipation and frictional losses in a counterflow double-pass solar thermal air heater. Results show that an increase in relative roughness height leads to marginal improvement in Nusselt number, with the combination of circular rings and ribs configuration performing the best in terms of Nusselt number.
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
(2021)
Article
Chemistry, Analytical
Georgia Kontaxi, Yorgos G. Stergiou, Aikaterini A. Mouza
Summary: This study compares the characteristics of bubbles formed in non-Newtonian and Newtonian fluids, finding that the final diameter of the bubbles is influenced by the gas flow rate and liquid phase viscosity. Simulation results indicate that high shear rates around bubbles in non-Newtonian fluids lead to the viscosity approaching its asymptotic value.
Article
Computer Science, Interdisciplinary Applications
Goncalo Silva
COMPUTERS & FLUIDS
(2020)
Article
Multidisciplinary Sciences
Goncalo Silva, Irina Ginzburg
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
(2020)
Article
Pharmacology & Pharmacy
Tiago Porfirio, Francisco J. Galindo-Rosales, Laura Campo-Deano, Joao Vicente, Viriato Semiao
Summary: The study provides rheological characterization of commonly used polymers and solvents for formulating amorphous solid dispersions using spray drying. Different polymers exhibit distinct rheological behaviors, which can aid in understanding spray drying processes.
EUROPEAN JOURNAL OF PHARMACEUTICAL SCIENCES
(2021)
Article
Mechanics
Irina Ginzburg, Goncalo Silva
Summary: The study introduces two new methods for addressing boundary and interface-conjugate conditions in LBM, aiming to improve locality, accuracy, and parametrization. These methods enable the accurate restoration of first- and second-order derivatives in arbitrary-directional flow fields.
Article
Construction & Building Technology
Nuno Serra, Viriato Semiao
Summary: Built environments are major energy consumers, and tools supporting their efficient design and guaranteeing comfort and air quality are crucial. Computational Fluid Dynamics (CFD) procedures have been widely used for predicting built environment flows with the optimization of pressure-velocity coupling being a possible strategy to reduce computational time.
BUILDING AND ENVIRONMENT
(2021)
Article
Thermodynamics
Duarte Pereira de Araujo Coutinho, Jorge Augusto Maciel Milhomem Rodrigues, Aires Jose Pinto dos Santos, Viriato Sergio de Almeida Semiao
Summary: The study introduces a thermoeconomic model for a distributed-scale hybrid solar-thermal power plant, which utilizes a genetic algorithm for multi-objective optimization to obtain a set of Pareto-optimal designs. The optimized designs significantly reduce levelized electricity costs, improve system efficiencies, and increase solar shares.
ENERGY CONVERSION AND MANAGEMENT
(2021)
Article
Engineering, Biomedical
Vahid Goodarzi Ardakani, Alberto M. Gambaruto, Goncalo Silva, Ricardo Pereira
Summary: A physics-based medical image segmentation method is proposed, which utilizes numerical simulations of fluid flow in porous material to extract target objects from medical images. The method is tested on real cases and validated through comparison with other segmentation techniques.
INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING
(2022)
Article
Computer Science, Interdisciplinary Applications
Goncalo Silva, Irina Ginzburg
Summary: Slip flows in ducts, especially in microchannel flows, are of great importance in engineering applications. This study focuses on the modeling of the slip velocity boundary condition in the lattice Boltzmann method (LBM) for steady slow viscous flows inside ducts of nontrivial shapes. A new approach called the local second-order boundary (LSOB) method is proposed to handle slip velocity condition, and its accuracy and consistency are examined against alternative schemes. Numerical tests confirm the advanced accuracy characteristics of the proposed LSOB slip boundary scheme, revealing the added challenge of the wall slip modeling.
INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS
(2022)
Article
Dentistry, Oral Surgery & Medicine
Mario Rito Pereira, Goncalo Silva, Viriato Semiao, Vania Silverio, Jorge N. R. Martins, Paula Pascoal-Faria, Nuno Alves, Juliana R. Dias, Antonio Ginjeira
Summary: This study experimentally validated a computational fluid dynamics (CFD) model by using micro-particle image velocimetry (micro-PIV) measurements of the irrigation flow velocity field developed in confluent canals. The results showed a good agreement between the micro-PIV experimental and CFD predicted data, indicating that laminar CFD modeling is reliable for predicting flow in similar domains.
INTERNATIONAL ENDODONTIC JOURNAL
(2022)
Article
Computer Science, Interdisciplinary Applications
Goncalo Silva
Summary: This study presents a detailed numerical analysis of one-dimensional, time-dependent reaction-diffusion equations using the lattice Boltzmann method with the two-relaxation-time scheme. The study has practical applications in various engineering problems and addresses the issue of solution-dependent sources in the lattice Boltzmann method. The study also provides strategies to improve the accuracy of the numerical scheme based on truncation error analysis.
COMPUTERS & FLUIDS
(2023)
Article
Dentistry, Oral Surgery & Medicine
Mario Rito Pereira, Goncalo Silva, Viriato Semiao, Jorge N. R. Martins, Vania Silverio, Paula Pascoal-Faria, Isabel Duarte, Nuno Alves, Antonio Ginjeira
Summary: This study assesses the influence of root canal preparation, irrigation needle design, and its placement depth on the irrigation flow of confluent canals. The results show that apical penetration and renewal of the irrigant are most efficiently achieved with the use of a 30G open-ended needle and a 30/.07v preparation.
AUSTRALIAN ENDODONTIC JOURNAL
(2023)
Article
Physics, Fluids & Plasmas
Irina Ginzburg, Goncalo Silva, Francesco Marson, Bastien Chopard, Jonas Latt
Summary: The goal of this work is to improve the existing lattice Boltzmann Dirichlet velocity boundary schemes for inclined walls, curved surfaces, and narrow gaps by enhancing their accuracy, stability, locality, and mass conservation. This is achieved through two infinite-member boundary classes: the LI+ and the EMR. The LI+ class unifies all directional rules and proposes three groups of non-equilibrium local corrections, while the EMR class extends the accuracy to grid-rotated linear Couette flow. Numerical tests are conducted to determine the optimal schemes for creeping and inertial flow regimes.
Article
Physics, Fluids & Plasmas
Bart Postma, Goncalo Silva
Article
Thermodynamics
Navid Freidoonimehr, Azadeh Jafari, Maziar Arjomandi
Summary: In this study, a high-fidelity flow visualisation technique is used to investigate the resemblance between a turbulent boundary layer generated by different tripping devices in a lab environment and a naturally developed canonical turbulent boundary layer. The study finds that the blockage created by trips is the main factor affecting the turbulence statistics at a certain downstream distance.
INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW
(2024)
Article
Thermodynamics
Yuning Wang, Alberto Solera-Rico, Carlos Sanmiguel Vila, Ricardo Vinuesa
Summary: This study proposes a method that combines 6-VAEs for modal decomposition and transformer neural networks for temporal-dynamics prediction in the latent space to develop reduced-order models (ROMs) for turbulent flows. The method achieves high reconstruction accuracy and accurate prediction of temporal dynamics.
INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW
(2024)
Article
Thermodynamics
L. Laguarda, S. Hickel, F. F. J. Schrijer, B. W. van Oudheusden
Summary: Wall-resolved large-eddy simulations were used to investigate the Reynolds number effects in supersonic turbulent boundary layers at Mach 2.0. The study covered a wide range of friction Reynolds numbers and identified trends in various statistics and scaling laws. The size and topology of turbulent structures in the boundary layer were examined, with a focus on the outer-layer motions at high Reynolds numbers. The study also assessed the influence of outer-layer structures on near-wall turbulence and the sensitivity of uniform momentum regions to compressibility.
INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW
(2024)
Article
Thermodynamics
A. Doehring, T. Kaller, S. J. Schmidt, N. A. Adams
Summary: In this study, well-resolved large-eddy simulations were used to investigate turbulent duct flows with a square cross section. The influence of a modified wall shear stress on the secondary flow was analyzed by artificially modifying the wall shear stress at one of the four walls. The results showed that the modification led to an asymmetrical distribution of the secondary flow source terms, affecting the momentum distribution. Furthermore, the anisotropy of the Reynolds stress tensor, which induces the secondary flow vortices, was significantly affected by the wall shear stress modulation.
INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW
(2024)
