Journal of Advanced Research in Numerical Heat Transfer

Numerical Simulation of Surface Pressure and Temperature Distribution along a Cone at Supersonic Mach Numbers using CFD

Sun, 15 Dec 2024 00:00:00 +0700

The primary focus of this study is to use numerical simulations to analyze the static temperature and surface pressure distribution along the slant length of a cone at different Mach numbers and a range of semi-cone angles. Computational fluid dynamics (CFD) analysis numerically simulates temperature and surface pressure distribution. This research considers parameters such as supersonic Mach numbers, semi-cone angles, and different locations along the slant length of a cone. The study examines Mach numbers of 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, and 5.0, along with cone angles ranging from 3° to 21°. The static temperature and pressure (P/Pa) results are measured at different locations (x/L) along the slant length of the cone, ranging from 0.1 to 1. The results for static temperature and pressure distribution obtained by CFD analysis are compared with results obtained by regression model at various Mach numbers and constant semi-cone angle (θ) = 12°. The results from the CFD analysis and the findings of the regression methodology are in agreement. This study found that the Mach number, semi-cone angle, and the various locations along the cone's slant length significantly impact the variation of static temperature and surface pressure distribution. As the Mach number and the semi-cone angle increase, the temperature and pressure distribution along the slant length of the cone also increase.

Thermal Optimalization with CFD Analysis and Real-Time Performance Identification in Briquette Ovens Using Modbus-Based Communication

Sun, 15 Dec 2024 00:00:00 +0700

Briquette ovens that utilize biomass energy frequently face obstacles in achieving consistent heat distribution, resulting in ineffective energy usage and varying product quality. This study tackles these challenges by merging Computational Fluid Dynamics (CFD) analysis, performed with Cradle software, alongside a Modbus-based temperature data acquisition system to significantly boost energy efficiency and temperature regulation. A total of 32 K-type thermocouples were meticulously positioned within the oven to gather real-time temperature data, which was processed through LabVIEW. CFD simulations revealed irregular heat distribution patterns, especially at the rear of the oven. The temperature data obtained via Modbus corroborated these observations, allowing for strategic modifications to enhance heat distribution and minimize energy loss. The system achieved an impressive accuracy rate of 98.89%, with a mere error margin of 1.11%, substantially elevating the oven’s energy efficiency and briquette drying capabilities. This research clearly illustrates that the integration of CFD modeling with real-time data acquisition constitutes a powerful method for optimizing the functionality of industrial heating systems.

Influence of MHD Flow on Shrinking Sheet with Partial Slip and Heat Generation at Stagnation Point

Sun, 15 Dec 2024 00:00:00 +0700

Fluid dynamics encompasses the fundamental principles of continuity, momentum, and energy conservation, which are applied through mathematical models like the Navier-Stokes equations. These equations are essential for describing how fluid properties like velocity, pressure, and density change in response to forces and environmental conditions. Thus, this study attempted to explore the characteristics of flow and heat transfer of a shrinking sheet in magnetohydrodynamics (MHD), along with the effect of partial slip and heat generation on the system. We employ a similarity transformation technique for turning the governing partial differential equations into ordinary differential equations. These equations are solved numerically through shooting method in Maple, and the results are compared to the previous research. The analysis shows that the suction parameter and velocity slip parameter have an increasing effect on both the skin friction rate and the heat transfer rate. In the meantime, the heat transfer rate decreases as the parameter increases for the heat generation, magnetic parameter, Eckert number and thermal slip parameter. The bvp4c solver in MATLAB is implemented to conduct a stability analysis and determine the physically feasible solution. According to our research, the stability of the solution occurs only in the first solution.

Transport Process of Virus Concentration from Airway to Cerebral Artery by using Computational Fluid Dynamics

Sun, 15 Dec 2024 00:00:00 +0700

When a person infected with the virus releases aerosol including the virus by sneezing or talking, the virus stays in atmosphere for a long time. If other persons inhale the virus, the person maybe infected. In our previous researches, in order to decrease efficiently the risk of infection, various indoor ventilation conditions have been evaluated by analyzing transport process of the virus concentration using Computational Fluid Dynamics (CFD). From them, it was found that indoor ventilation condition can be optimised by evaluating amount of the virus concentration and residence time. However, the infection process in air way and vascular when these airborne viruses from indoor air is inhaled has not been elucidated yet. In this research, a couple analysis from nasal cavity to cerebral artery via organ is tried to be applied in order to analyze the transport process of virus concentration from nasal cavity to cerebral artery. In addition, the effect of breathing waveforms and virus proliferation on the virus infection is evaluated. Regarding the methods, 3D CAD model of these three parts is created. Continuity equation, Navier-Stokes equation and transport equations of virus concentration are used as the governing equations. The transport equations in the organ is modified with the virus proliferation. Inlet boundary conditions in the nasal cavity are set up to be four types of breathing waveforms. A boundary condition between the nasal cavity and the organ is continuity of virus concentration at the contact surface. Similarly, the other boundary condition between the organ and the cerebral artery is continuity of virus concentration. As results, it was found that the virus concentration in the cerebral artery in case of sinusoidal breathing waveform with long period is the smallest. It was also found that the virus concentration in the organ and the cerebral artery in case of proliferation within the organ is higher than that has no proliferations. It is concluded that a method for minimalizing risk of virus infection can be proposed by the couple analysis.

Hybrid Nanofluids in Solar Thermal Collectors: Size and Cost Reduction Opportunities

Sun, 15 Dec 2024 00:00:00 +0700

Solar thermal collector, an alternative way to harvest renewable solar energy, requires high heat transfer area. Hybrid nanofluid has potential to reduce the size of the collector due to its high thermal conductivity and low specific heat capacity. This study investigates the effects of Multi-Walled Carbon Nanotubes (MWCNT) combine with metal oxides, including Al₂O₃, CeO₂, TiO₂, ZnO at the volume ratio of 1:4 between MWCNT and metal oxides with a total of 1 vol.% in water. The investigation focuses on assessing this nanofluids with 1 kg/min mass flow rate for its effect in size and cost reduction. Following the validation of nanofluids properties predictor and the numerical model of flat plate solar collector with experimental data, the effects in terms of size and cost reduction is evaluated. In best case scenario, the use of MWCNT-TiO₂can reduce the size of flat plate solar thermal collector by up to 8.54% and cost by 5.15% compared to using water as the heat transfer fluid.

Application of the Phase Field Approach for Crack Propagation in Viscoelastic Solid Materials under Thermal Stress: A Case Study of Solder Fracturing

Sun, 15 Dec 2024 00:00:00 +0700

To date, solder has been a crucial component for interconnecting circuit boards (PCBs) and electronic components in the electronics industry. However, solder faces certain challenges, such as cracking due to thermal changes. This paper investigates solder cracking under thermal expansion. We employ a phase field model to study crack propagation under thermal stress in a square domain and in solder with a fillet shape. The model is based on those proposed by Takaishi-Kimura and Alfat, where the stress and strain tensors are modified to account for variations in the temperature field. In this study, we consider the solder material to be viscoelastic, while the other materials are treated as homogeneous and isotropic. A numerical example is computed using the adaptive mesh finite element method, with the code implemented in FreeFEM software. The results of this study are in good agreement with previous numerical and experimental findings.

Effects of Newtonian Heating on MHD Jeffrey Hybrid Nanofluid Flow via Porous Medium

Sun, 15 Dec 2024 00:00:00 +0700

In recent years, hybrid nanoparticles have gained significant attention for their ability to enhance thermal conductivity in various fluid systems, making them effective heat transport catalysts. Despite advancements in thermal fluid technology, a gap remains in understanding how hybrid nanoparticles interact within non-Newtonian Jeffrey fluid systems, particularly under complex boundary conditions like Newtonian heating. The present study aims to shed light on the effect of hybrid nanoparticles (alumina and copper) incorporated into a Jeffrey fluid model on flow and heat transport, considering them as heat transport catalyst and subject to Newtonian heating to optimize thermal efficiency. An exponentially accelerated plate is used to induce the fluid flow, taking into account the effects of porosity, MHD, and thermal radiation. The examined fluid exhibits an unsteady one-dimensional flow, formulated by deriving partial differential equations, which are subsequently transformed into ordinary differential equations using suitable non-dimensional variables and the Laplace transformation. This research distinguishes itself by presenting a novel mathematical model for MHD Jeffrey hybrid nanofluid, accounting for porosity and Newtonian heating effects. The inverse of Laplace is used to generate the exact solutions for velocity and temperature profiles, which is not explored in existing literature. Graphical representations are generated using Mathcad, depicting the velocity and temperature distributions. A comparison with prior study from the literature demonstrates strong agreement between our findings and theirs. The findings indicate that the velocity and temperature profiles of the hybrid nanofluid are higher with Newtonian heating than without it. Additionally, an increase in the Grashof number, radiation, acceleration, and porosity parameters also leads to an enhanced velocity profile.

Thermal and Flow Characteristics of Alumina Nanofluids in Microfluidic Systems: A Low-Concentration Study

Sun, 15 Dec 2024 00:00:00 +0700

Microfluidic technologies and nanofluids represent a synergistic combination with significant potential for enhancing heat transfer and thermal management applications. This study investigates the thermal and flow characteristics of a 0.001 wt.% alumina (Al₂O₃)-water nanofluid within a custom-designed serpentine microfluidic channel. The nanofluid was prepared and characterized for its thermal conductivity, viscosity, specific heat, and density. Experimental microfluidic studies, supplemented by numerical simulations, were conducted to evaluate the fluid's behavior under controlled conditions. Results indicated a slight increase in thermal conductivity for the Al₂O₃ nanofluid compared to pure water, with increments ranging from 0.16% at 20°C to 0.30% at 80°C, attributed to enhanced Brownian motion of the nanoparticles. Viscosity measurements revealed marginal increases, suggesting minimal impact on fluid flow dynamics. The microfluidic experiments demonstrated a consistent pressure gradient and laminar flow regime, essential for precise control and efficient thermal management. Temperature contours showed effective heat dissipation, with a steady thermal gradient from the inlet to the outlet. The study concludes that low-concentration Al₂O₃ nanofluids can enhance thermal performance in microfluidic systems without significantly affecting flow characteristics, making them suitable for applications requiring efficient heat dissipation, such as electronic cooling and chemical reactions. These findings provide a foundation for future research into higher nanoparticle concentrations and different base fluids, aimed at optimizing the thermal and flow properties of nanofluids in microfluidic environments. The integration of nanofluids with microfluidic technologies holds promise for advancing the performance and reliability of next-generation thermal management systems.

Computational Simulation of MHD Blood-Based Hybrid Nanofluid Flow through a Stenosed Artery

Sun, 15 Dec 2024 00:00:00 +0700

As the leading cause of death worldwide, cardiovascular disease underscores the urgent need for effective therapies and diagnostic tools. The use of magnetic fields and nanoparticles has demonstrated potential for creating cutting-edge treatments. To analyse blood flow in an artery with stenosis and the impact of an external magnetic field on blood flow infused with hybrid nanoparticles, this study is conducted. A generalised power law is used to model the flow of a hybrid blood nanofluid comprising silver (Ag) and gold (Au) nanoparticles. This study focuses on a deeper level of the magnetic field with hybrid nanoparticles in a non-Newtonian fluid, which extends from previous studies on nanoparticles in Newtonian blood. In a straight artery, the blood flow through a cosine-shaped stenosis is simulated using COMSOL Multiphysics software. The physical controlling parameters, including velocity profiles and wall shear stress, are illustrated through graphs. The external magnetic field significantly reduces shear stress and the velocity profile. The addition of gold and silver nanoparticles allows for smooth blood flow in the diseased artery. The findings show a decline in aberrant behaviour and recirculation in the post-stenotic area. The combination of a hybrid nanofluid with an external magnetic field presents a practicable method for improving blood flow in stenosed arteries. The results have implications for targeted drug delivery in stenotic arteries and advancements in nanomedicine.

Investigation of Al₂O₃:Cu Hybrid Nanofluid Composition in Jet Impingement Cooling: Numerical Analysis

Sun, 15 Dec 2024 00:00:00 +0700

Hybrid nanofluids have emerged as a promising medium for enhancing heat transfer in various cooling systems, particularly in jet impingement cooling applications. This study conducts a numerical analysis of the heat transfer performance of aluminium oxide (Al₂O₃) and copper (Cu) hybrid nanofluids at different mixing ratios (25:75, 50:50, and 75:25) under jet impingement cooling conditions. The research employs computational fluid dynamics (CFD) simulations to investigate the thermophysical properties and heat transfer behaviour of these hybrid nanofluids at a constant nanoparticle concentration of 0.5% by volume. Among the tested compositions, the 50:50 Al₂O₃ mixture demonstrated the highest heat transfer coefficient and surface temperature reduction, improving heat transfer by up to 22.20% compared to pure water. The findings suggest that the balanced thermal properties of this ratio has optimized cooling performance, making it suitable for industrial cooling applications, such as electronics and power systems, where efficient heat dissipation is critical.