Article
Thermodynamics
Cong Qi, Zi Ding, Jianglin Tu, Yuxing Wang, Yinjie Wang
Summary: The study found that increasing the number of steps will increase the Nu value of the downstream wall of the steps. The increase in flow velocity has the greatest influence on the Nu value of the lower wall of the step, and the heat exchange effect of the hybrid nanofluids is better than that of water.
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
(2021)
Article
Thermodynamics
Saad Inam, Marcello Lappa
Summary: This study numerically investigates the unsteady mixed forced-buoyancy convection in a channel with a backward facing step. By setting some portions of the boundary as isothermal or adiabatic surfaces, the interplay of forced and buoyancy convection under different conditions is explored. The results reveal a variety of mechanisms involved in this interaction, ranging from standard hydrodynamic phenomena to buoyant effects.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Environmental Sciences
Pinar Sari Cavdar, Bekir Solmaz, Fatih Selimefendigil, Ali Yurddas
Summary: In this study, the numerical investigation of pulsating forced convection in a backward-facing step flow using water-based nanofluids was conducted, and it was found that increasing the Cu nanoparticle volume ratio improves heat transfer efficiency.
ENVIRONMENTAL ENGINEERING AND MANAGEMENT JOURNAL
(2021)
Article
Thermodynamics
Duna T. Yaseen, Amani J. Majeed, Muneer A. Ismael
Summary: This paper investigates the mixed convection heat transfer and fluid-structure interaction (FSI) of a hot cylinder placed in a backward-step channel. The influence of different configurations of a flexible step on cooling performance was evaluated. Results showed that adjusting the flexibility of the step can improve heat transfer performance and fluid dynamics at low Reynolds number.
THERMAL SCIENCE AND ENGINEERING PROGRESS
(2022)
Article
Thermodynamics
Saurav Kumar, Manash Protim Boruah, Sukumar Pati
Summary: The hydrothermal performance of viscoplastic fluid flowing through a backward facing step channel is studied. The Bingham number, Reynolds number, and power law index are analyzed for their effects on thermal and flow characteristics. Results show that an increase in Bingham number leads to a decrease in reattachment length and an increase in temperature drop. The local Nusselt number peaks near the step and increases with Bingham number.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2023)
Article
Engineering, Multidisciplinary
Ahmed H. Abdelaziz, Wael M. El-Maghlany, Ahmed Alaa El-Din, Mohamed A. Alnakeeb
Summary: This study numerically investigates the mixed convective heat transfer and pressure drop of nanofluids in an isothermal horizontal tube. The results show that nanofluids can enhance heat transfer, with the maximum average Nusselt number increase of 15.5% for Al2O3. Ionic nanofluids demonstrate promising results with a significant increase (37%) in the Nusselt number, while hybrid nanofluids show no enhancement.
ALEXANDRIA ENGINEERING JOURNAL
(2022)
Article
Mechanics
Q. Luo, G. Dolcetti, T. Stoesser, S. Tait
Summary: The water surface response to turbulent flow over a backward-facing step is investigated using high-resolution large-eddy simulation (LES). The LES method is validated using experimental data and the analysis reveals the interplay between turbulence structures and the dynamics of the water surface. The water surface deformation is mainly influenced by gravity waves and turbulence-driven forced waves. The study highlights the importance of decomposing water surface fluctuations to understand the underlying flow structure dynamics.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Mechanics
Petteri Peltonen, Pekka Kanninen, Erkki Laurila, Ville Vuorinen
Summary: The study on wave formation behind the free surface backward facing step (FSBFS) shows that the wave shape cannot be solely characterized by the Froude number. Different conditions of step draught and inflow boundary layer profiles lead to variations in wave characteristics.
Article
Thermodynamics
Abd Rahim Abu Talib, Ali Kareem Hilo
Summary: The study found that combining a corrugated wall with a BFS channel can significantly enhance heat transfer, but also increases friction. The channel with a 4mm amplitude height and 20mm wavelength performed the best at 5000 Re, reaching a performance evaluation criterion factor of 1.33.
CASE STUDIES IN THERMAL ENGINEERING
(2021)
Article
Chemistry, Physical
B. Pekmen Geridonmez, Hakan F. Oztop
Summary: This paper numerically studies the mixed convection flow of hybrid nanofluid in a backward facing step channel with a uniform partial magnetic field, considering different inlet velocity profiles. The results show that the smallest convective heat transfer occurs in the step-centered partial magnetic field, and an increase in magnetite nanoparticles significantly affects convective heat transfer.
Article
Chemistry, Multidisciplinary
Xiangcheng You, Shiyuan Li
Summary: This study investigates the convective heat transfer of a hybrid nanofluid in an inclined channel through analytical methods. The results show that nanoparticle volume fractions play a key role in delaying the occurrence of flow reversal, with hybrid nanofluids having a longer delayed range compared to conventional nanofluids.
Article
Thermodynamics
Rouhollah Moosavi, Reza Moltafet, Cheng-Xian Lin, Po-Ya Abel Chuang
Summary: The study focuses on the unsteady flow and natural convection heat transfer of fractional Maxwell viscoelastic fluid over sudden expansion geometry, showing that the fractional derivative parameters and physical parameters have significant effects on Nusselt number, friction coefficient, velocity, and temperature.
THERMAL SCIENCE AND ENGINEERING PROGRESS
(2021)
Article
Thermodynamics
Thomas McQueen, David Burton, John Sheridan, Mark C. Thompson
Summary: This work provides new insight into the transient flow effects of forcing a backward-facing step flow at high Reynolds number. Notably, this research considerably extends the Reynolds number ranges of previous studies and examines the effect of periodic shear-layer forcing on the global mean and fluctuating flow structure. The study also investigates the influence of forcing on the distribution of key instabilities in the flow.
INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW
(2022)
Article
Mathematics, Applied
Yadong Huang, Desheng Zhang, Fadong Gu
Summary: The study investigated the effect of a streamwise Lorentz force applied in the primary and secondary separation bubbles on the base flow and the amplification rate of perturbation energy. The results showed that the convective term promotes the growth rate while the viscous term usually plays a suppressing role.
APPLIED MATHEMATICS AND MECHANICS-ENGLISH EDITION
(2021)
Article
Thermodynamics
Nidhi Singh, Manish K. Khandelwal
Summary: This study reports the instability properties of mixed convection flow of different nanofluids in a differentially heated vertical channel through a linear stability analysis. The results show that increasing the concentration of nanoparticles in the water improves the stability of the basic flow, while increasing the Reynolds number destabilizes the basic flow of nanofluid.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2022)
Article
Energy & Fuels
Husam Naufal Saleh Yassien, Omar Rafae Alomar, Mothana M. Mohamed Salih
Article
Engineering, Mechanical
Mothana M. Mohamed Salih, Omar Rafae Alomar, Husam Naufal Saleh Yassien
Summary: This study compares the performance of two solar air heaters with double glass covers under natural and forced air circulation conditions, finding that natural convection operation leads to better efficiency. The results suggest that adding a porous medium and the type of air circulation have a considerable impact on heat transfer rates.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2021)
Article
Thermodynamics
Ayad S. Abdallah, Nabil Jamil Yasin, Hani Aziz Ameen
Summary: This research experimentally examined the use of Heat Pipe Heat Exchanger (HPHE) to reduce energy consumption in air-conditioning systems while maintaining the required temperature level. The study found that increasing the mass concentration of copper oxide (CuO) nanoparticles and inlet air temperature led to higher temperatures in the evaporator and condenser. Additionally, it was discovered that higher inlet air temperature and CuO mass concentration resulted in improved effectiveness of the heat pipe, with the highest effectiveness and maximum heat recovery value found at an inlet air temperature of 55 degrees C.
FRONTIERS IN HEAT AND MASS TRANSFER
(2022)
Article
Thermodynamics
Asmaa Taha Hussein, Ayad S. Abedalh, Omar Rafae Alomar
Summary: This study focuses on enhancing the performance of a vapor compression cycle by using Polyol Oil Ester (POE) with nano copper oxide (CuO) and a fluidized bed for condenser cooling. The efficiency of the modified system, using nano CuO and a fluidized bed, was compared to that of the normal system using only POE oil. Different volume fractions of CuO (0.1%, 0.3%, and 0.5%) were used. The results showed that adding nanoparticles and using a fluidized bed improved the refrigeration system's performance, with a significant increase in the coefficient of performance and a reduction in power consumption.
CASE STUDIES IN THERMAL ENGINEERING
(2023)
Article
Thermodynamics
Husam Naufal Saleh Yassien, Almohammed Omar Abdulhadi Mustafa, Ammar Hassan Soheel, Fouad Ibrahim Alhajj Hassan
Summary: By using this instrument, the thermal conductivity of sawdust can be measured without changing its physical properties, and there is no need to use adhesive materials to shape the specimen. Wood sawdust is classified into three groups based on pellet size. No mechanical or chemical processes were carried out on the specimens to maintain their thermal properties. The effect of moisture content was eliminated by drying the specimens at 100 degrees C for 30 minutes. The thermal conductivity of all samples is inversely proportional to the working temperature. The first model (wo1) is a good choice for flat plate solar collector insulation due to its low thermal conductivity and affordability.
INTERNATIONAL JOURNAL OF HEAT AND TECHNOLOGY
(2023)
