Article
Engineering, Marine
Mehrnoush Kharghani, Mahmoud PasandidehFard, Mohammad Naeimirad
Summary: The study found that increasing momentum flow rates affect boundary layer thickness, change vortex shapes, and lead to more stretching. Turbulence phase delay is almost the same in both streamwise directions, but varies in the wall-normal direction and is related to the physical shape of eddies. The outer region of the boundary layer is more severely affected compared to the near-wall region.
Article
Mathematics, Applied
Feng Liu, Le Fang, Jian Fang
Summary: Recent studies have shown that in transitional boundary-layer flow, there are different streamwise zones for the transition region and non-equilibrium turbulence region, exhibiting different non-equilibrium scalings. Additionally, in the wall-normal direction, the viscous sublayer, log layer, and outer layer exhibit non-equilibrium phenomena distinct from other types of turbulence. These findings are expected to inform the modeling of various non-equilibrium turbulent flows.
APPLIED MATHEMATICS AND MECHANICS-ENGLISH EDITION
(2021)
Article
Thermodynamics
A. K. Jha, P. Shukla, Pranav M. Khisti, Pradyumna Ghosh, S. K. Yadav
Summary: This work investigates the onset of velocity transition in free convection boundary layer over a 45 inclined plate through experimental investigation. The impact of various hydrodynamic parameters and heat flux values on the transition is studied, and it is found that the initiation of transition is characterized by an increase in overall velocity boundary layer thickness, with the distance from the leading edge where the transition begins decreasing with an increase of heat flux.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2023)
Article
Mechanics
X. Q. Cheng, C. W. Wong, F. Hussain, W. Schroeder, Y. Zhou
Summary: An experimental study was conducted on controlling a turbulent boundary layer (TBL) on a flat plate using plasma actuators, resulting in a drag reduction of up to 26%. The study found that the drag reduction phenomenon persists downstream, with three distinct spatial regions characterized by drag increase, pronounced drag reduction, and drag recovery, all related to large-scale streamwise vortices.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Multidisciplinary Sciences
J. Huertas, D. S. Martinez, D. F. Prato
Summary: The study used CFD to investigate the impact of different atmospheric stability conditions on pollutant dispersion, showing a strong correlation between pollutant concentrations near emission sources and those under neutral conditions. Under extremely stable atmospheric conditions, pollutant concentrations near road sources were found to be up to 12 times higher compared to neutral conditions.
SCIENTIFIC REPORTS
(2021)
Article
Chemistry, Physical
Fernando J. Beltran, Javier Rivas, Juan-Fernando Garcia-Araya
Summary: This study addressed the challenge of establishing the rate of photon absorption in external photoreactors by adapting SFM equations developed for central lamp photoreactors. The results showed slight differences from those obtained using the Monte Carlo method. Additionally, intrinsic rate constants and scavenging factors for the photocatalytic oxidation of contaminant compounds were determined based on the validated photon absorption rate.
Article
Mechanics
A. A. Abramov, A. V. Butkovskii
Summary: The article discusses the Reynolds analogy for fluid flow past a flat plate at zero incidence, showing that for a viscous incompressible fluid, there is a maximum in the Reynolds analogy as a function of Prandtl number at any positive Eckert number. For rarefied gas flow, an extended Reynolds analogy is investigated, with a weak dependence on Knudsen number for supersonic monatomic rarefied gas flows at a Knudsen number close to 0.5. The extended Reynolds analogy for supersonic gas flow is found to depend mainly on plate velocity, temperature, and undisturbed gas temperature through Knudsen and Eckert numbers.
Article
Mechanics
H. Otto, C. Cierpka
Summary: This study investigates experimental convective flows in vertically stratified environments to complement theoretical studies and reveals fundamental physical mechanisms in stratified vertical convection.
Article
Engineering, Mechanical
Hai-Bo Niu, Shi-He Yi, Jun-Jie Huo, Wen-Peng Zheng, Xiao-Lin Liu
Summary: An experimental study on the traveling crossflow instability over a 60 degrees swept flat plate was conducted, visualizing the waves and secondary instability using NPLS technique. Wavelet transform was used to study wavelength contents, showing stable amplification before secondary instability occurred. The effects of Reynolds number on boundary layer transition and traveling crossflow instability were discussed.
ACTA MECHANICA SINICA
(2021)
Article
Energy & Fuels
Muhammad Ehtisham Siddiqui, Ammar A. Melaibari, Fahad Sarfraz Butt
Summary: This study investigates the interaction between transverse injection of cold air and the boundary layer over a heated flat plate. The results show that injecting cold air near the plate can increase the thickness of the thermal boundary layer.
Article
Thermodynamics
Kosuke Nakagawa, Takahiro Ishida, Takahiro Tsukahara
Summary: In a three-dimensional boundary layer, roughness and external turbulence play different roles in the induction of crossflow vortices, leading to turbulent transition. Long-wavelength turbulence promotes early transition by inducing crossflow vortices, while short-wavelength turbulence interacts with wake vortices induced by roughness, resulting in hairpin vortices. These different transition mechanisms are influenced by velocity gradients at different locations.
INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW
(2023)
Article
Thermodynamics
Nahid Fatima, Walid Belhadj, Kottakkaran Sooppy Nisar, Usman, Mohammed Kbiri Alaoui, Muhammad Bilal Arain, Nouman Ijaz
Summary: Nanotechnology has the potential to revolutionize various industries and fields, including homeland security, food safety, information technology, healthcare, energy, transportation, and environmental research. A numerical study was conducted on the flow of a nanofluid with variable temperature on a moving flat plate in the presence of gyrotactic microorganisms. The study utilized similarity transformations to convert the partial differential equations governing the flow phenomena into ordinary differential equations, which were then solved numerically. The results showed the effects of various physical factors and demonstrated the potential for enhancing viscosity, thermal conductivity, thermal diffusivity, and convective heat transmission in base fluids like water and oil.
CASE STUDIES IN THERMAL ENGINEERING
(2023)
Article
Mechanics
Dhamotharan Veerasamy, Chris J. Atkin, Sathiskumar A. Ponnusami
Summary: This study investigates the characteristics of laminar-turbulent transition occurring on a flat-plate boundary layer due to the interaction with a non-impinging aerofoil wake, revealing differences from previously reported forced transition mechanisms. The experimental results demonstrate a combination of observed characteristics, including the presence of mixed transitional features and the influence of the gap between the aerofoil and the flat plate on disturbance profiles.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
T. Bon, J. Meyers
Summary: Recent studies have shown that surface roughness with dominant spanwise length scales can induce large secondary motions. This study investigates the effect of spanwise heterogeneous surface temperature on closed channel flow through direct numerical simulations. The results demonstrate that secondary flows are excited and influence the mean flow structure, skin friction, and heat transfer. The length scale of the surface temperature heterogeneity strongly affects the outer layer of the flow, while stronger stability reduces the impact of temperature on momentum and heat transfer.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
Thea J. Ellevold, John Grue
Summary: The instability and vortex shedding caused by internal solitary waves of depression propagating along a shallow pycnocline were computed. The results were in good agreement with laboratory experiments, but disagreed with existing computations. The instability boundary depended on the depth of the pycnocline and decayed with increasing depth and stratification Reynolds number. The oscillatory bed shear stress was strong and increased with scale, comparable to turbulent stress observed in the field.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Environmental Sciences
Nestor A. Urbina-Suarez, Darly D. Ayala-Gonzalez, Jennyfer D. Rivera-Amaya, Andres F. Barajas-Solano, Fiderman Machuca-Martinez
Summary: The study evaluated the effect of tannery wastewater on biomass and product production of three microorganisms. The results indicate that the use of a constant light regime and the concentration of real wastewater have a significant impact on biomass production.
Article
Electrochemistry
Bryan Acosta-Angulo, Jennyfer Diaz-Angulo, Jose Lara-Ramos, Ricardo Torres-Palma, Diana Martinez-Pachon, Alejandro Moncayo-Lasso, Fiderman Machuca-Martinez
Summary: This article explores the spread of genetic algorithms (GA) and particle swarm optimization (PSO) in the study of reaction kinetics using bibliometric analysis of the Scopus database. The study focuses on applications in advanced oxidation processes (AOPs), examining collaborations between countries and authors, and keyword co-occurrences. The findings reveal that GA methods are the preferred choice for reaction kinetic studies, with the USA being the most influential country in terms of collaboration. However, there is still a lack of collaboration among most countries, including authors. Furthermore, literature on AOPs remains scarce. The forecasting suggests that there will be further growth in the implementation of evolutionary algorithms, particularly PSO.
Review
Multidisciplinary Sciences
Rodrigo A. Munoz Meneses, Gerardo Cabrera-Papamija, Fiderman Machuca-Martinez, Luis A. Rodriguez, Jesus E. Diosa, Edgar Mosquera-Vargas
Summary: Pollution caused by plastic materials poses a negative impact on the health of the planet. Finding solutions to transform discarded plastics into new materials is crucial for establishing a circular and sustainable production model.
Review
Engineering, Electrical & Electronic
Deyler Castilla-Caballero, Omer Sadak, Jolaine Martinez-Diaz, Valentina Martinez-Castro, Fiderman Machuca-Martinez, Aracely Hernandez-Ramirez, Sofia Vazquez-Rodriguez, Sundaram Gunasekaran
Summary: The COVID-19 pandemic has led to a significant increase in plastic waste from single-use masks and other personal protective equipment (PPE). This review highlights the use of solid-state photocatalysis as an efficient technology to combat plastic pollution. Despite fewer publications in this field compared to aqueous and/or gaseous phase photocatalysis, the review provides an in-depth analysis of the incorporation of photocatalyst into plastic matrices and the evaluation of its effectiveness using various methods. The aim is to raise awareness and promote further research in this innovative area.
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
(2022)
Review
Multidisciplinary Sciences
Claudia M. Sichel-Crespo, Erika Y. Ortiz-Montoya, Nelson H. Caicedo-Ortega, Fiderman Machuca-Martinez
Summary: Global pork production is growing rapidly, but there is a lack of research on waste treatment. This study collected information on using digestate for microalgae cultivation and analyzed the current development, important topics, and key players. The findings show that China and the USA are the main contributors, and spirulina, astaxanthin, and beta-carotene are the main products.
Article
Electrochemistry
Eliana M. Jimenez-Bambague, Carlos A. Madera-Parra, Maria F. Rangel-Delgado, Isabel Quintero-Martinez, Daniela Miranda-Mosquera, Juan S. Aristizabal-Apolinar, Fiderman Machuca-Martinez
Summary: The objective of this study was to evaluate the performance of Photo-Fenton (PF) and Electro-Fenton (EF) processes for the removal of pharmaceutical compounds in wastewater. The operational conditions and removal efficiencies were assessed for both processes. EF showed a higher removal efficiency for all identified compounds, making it the best option for treating this real effluent.
ELECTROCHIMICA ACTA
(2023)
Article
Engineering, Chemical
Jose David Venecia-Nunez, Leidy Tatiana Ramirez-Parra, Jose Antonio Lara-Ramos, Fiderman Machuca-Martinez, Jose Angel Colina-Marquez, Miguel Angel Mueses
Summary: Caffeine, as a commonly found contaminant in the environment, has significant effects on aquatic species and human health. The study used a photocatalysis-based technique, O-3/UV/GHT, to degrade and mineralize caffeine in solution. By optimizing factors such as O-3 dose, GHT charge, agitation speed, pH, initial caffeine concentration, and UV light, the process achieved a degradation rate of approximately 99.97% in less than 20 minutes, with a mineralization rate of 38.02%.
CHEMICAL ENGINEERING & TECHNOLOGY
(2023)
Article
Biochemistry & Molecular Biology
Jose Munoz-Chilito, Jose A. Lara-Ramos, Lorena Marin, Fiderman Machuca-Martinez, Juan P. Correa-Aguirre, Miguel A. Hidalgo-Salazar, Serafin Garcia-Navarro, Luis Roca-Blay, Luis A. Rodriguez, Edgar Mosquera-Vargas, Jesus E. Diosa
Summary: The impacts of adding multi-walled carbon nanotubes (MWCNTs) on the properties of thermoplastic polyurethane (TPU) plates were investigated in terms of morphology, electrical conductivity, and hardness. TPU/MWCNT nanocomposite plates were fabricated using compression molding, with MWCNT loadings ranging from 1% to 7%. X-ray diffraction analysis indicated that the incorporation of MWCNTs increased the ordered range of the TPU polymer matrix. SEM images showed that the fabrication route used resulted in a uniform dispersion of nanotubes inside the TPU matrix, creating a conductive network for electronic conduction. Impedance spectroscopy revealed that the TPU/MWCNT plates exhibited percolation and tunneling conduction mechanisms, with increasing conductivity values as the MWCNT loading increased. Additionally, the addition of MWCNTs increased the Shore A hardness behavior of the TPU plates, despite a reduction in hardness compared to pure TPU.
Article
Environmental Sciences
Nestor A. Urbina-Suarez, Christian Rivera-Caicedo, Angel Dario Gonzalez-Delgado, Andres F. Barajas-Solano, Fiderman Machuca-Martinez
Summary: The research focuses on the use of advanced oxidation process (AOPs) with hydrogen peroxide (H2O2) and sodium bicarbonate (NaHCO3) for the treatment of tannery wastewater. The optimal process conditions for removing different compounds were found to be NaHCO3 1 M, H2O2 2 M, and 60 degrees C, with high removal efficiencies for color and ammoniacal nitrogen. This study concludes that AOPs using H2O2 and NaHCO3 are recommended for effective removal of color and ammoniacal nitrogen in tannery wastewater.
Article
Engineering, Multidisciplinary
Santiago Sinisterra, Ruben Camargo-Amado, Diego Trivino, Fiderman Machuca-Martinez
Summary: This article introduces a research methodology based on patent analysis and the behavior of technology over time. Two software were used to extract and analyze patent data, and the results of the technological maturity cycle and future projections of the technology were obtained. A case study on antibacterial and self-cleaning surfaces technology was conducted, and it was found that the technology is in the maturity phase. This methodology is important for decision-making in research and development.
REVISTA FACULTAD DE INGENIERIA, UNIVERSIDAD PEDAGOGICA Y TECNOLOGICA DE COLOMBIA
(2023)
Article
Environmental Sciences
Eliana M. Jimenez-Bambague, Carlos A. Madera-Parra, Fiderman Machuca-Martinez
Summary: The COVID-19 pandemic has had a significant impact on global health and the environment. The excessive use of pharmaceuticals during the pandemic has led to an increase in micropollutants entering the environment. Monitoring data in Cali, Colombia, shows a 91% increase in the concentration of analgesics and anti-inflammatory drugs in wastewater after the pandemic, which is associated with the consumption of these drugs for mild symptoms. This increase poses a high ecological threat, being 14 times higher than pre-COVID-19 levels.
CURRENT OPINION IN ENVIRONMENTAL SCIENCE & HEALTH
(2023)
Article
Engineering, Chemical
Nestor A. Urbina-Suarez, German L. Lopez-Barrera, Janet B. Garcia-Martinez, Andres F. Barajas-Solano, Fiderman Machuca-Martinez, Antonio Zuorro
Summary: The UV/H2O2 system in real tannery wastewater was evaluated using experimental design and optimal reaction surface analysis. pH and temperature were found to have the largest impact on the process. Acidic pH of 4.5-5.5 and temperatures between 50 and 70(degrees)C were found to improve COD and ammonium oxidation. The study confirmed the process conditions and evaluated the removal rates of nitrite, ammonium, chromium, chlorides, BOD, COD, and color.
Article
Engineering, Chemical
Nestor A. Urbina-Suarez, Cristian J. Salcedo-Pabon, Jefferson E. Contreras-Ropero, German L. Lopez-Barrera, Janet B. Garcia-Martinez, Andres F. Barajas-Solano, Fiderman Machuca-Martinez
Summary: This study investigates the influence of photoperiod and wastewater concentration on the growth of microalgae and cyanobacteria for the removal of environmentally significant parameters from dyeing wastewater. The findings indicate that extended photoperiods and higher wastewater concentrations enhance biomass production. Hapalosiphon and Chlorella sp. demonstrate better tolerance to wastewater toxicity and improved removal of COD and BOD.
Article
Engineering, Chemical
Nestor A. Urbina-Suarez, Cristian J. Salcedo-Pabon, German L. Lopez-Barrera, Janet B. Garcia-Martinez, Andres F. Barajas-Solano, Fiderman Machuca-Martinez
Summary: A bicarbonate-peroxide (BAP) system was used to improve the quality of industrial tannery wastewater. The I-optimal experimental design was used to optimize critical variables, including temperature, initial pH, bicarbonate, and H2O2 concentration. The experiments were conducted in 500 mL reactors with an operational volume of 250 mL and agitation at 550 rpm. The optimized conditions were validated using statistical analysis, and it was found that temperatures above 50 degrees C and slightly acidic initial pHs were crucial for the efficiency of the BAP system. The validated optimal data showed high removal percentages for various pollutants, surpassing other advanced oxidation processes (AOPs) used for similar types of water.
Article
Engineering, Multidisciplinary
Jennyfer Diaz-Angulo, Alfonso Barboza-Meza, Fiderman Machuca-Martinez, Miguel-Angel Mueses
Summary: Mathematical analysis and simulation of a discontinuous rectification column were conducted during the start-up process using an operational strategy. The research focused on establishing a mathematical model based on the equilibrium state and utilized MESH equations for solution. The results were validated by experimental data, demonstrating the effectiveness of the proposed solution.
REVISTA FACULTAD DE INGENIERIA, UNIVERSIDAD PEDAGOGICA Y TECNOLOGICA DE COLOMBIA
(2022)