Comparison on Electrode and Ground Arrangements Effect on Heat Transfer under Electric Force in a Channel and a Cavity Flow

This study numerically investigates the effects of Electrohydrodynamic on flow patterns and heat transfer enhancement within a cavity which is on the lower wall of channel. In this simulation, effects of using ground wire and ground plate on the flow patterns are compared. Moreover, the positions of electrode wire respecting with ground are tested in the range of angles θ = 0 - 180°. High electrical voltage exposes to air is 20 kV. Bulk mean velocity and temperature of inlet air are controlled at 0.1 m/s and 60°C, respectively. The result shows when electric field is applied, swirling flow is appeared in the channel. In addition, swirling flow patterns in the main flow of using ground plate are widely spreader than that of using ground wire. Moreover, direction of swirling flow also affects the flow pattern and heat transfer in a cavity. These cause the using ground wire to give the maximum temperature and heat transfer higher than using ground plate. Furthermore, when the angle is at θ = 60°, high shear flow effect is obtained. This results show high strength of swirling flow and effective heat transfer enhancement

Performance and Emission Characteristics of a Single-Cylinder Diesel Engine Fueled with Yang (Dipterocarpus alatus) Oil

The objective of this study was to determine the performance and emission of diesel engine using Yang (Dipterocarpus alatus) oil compared with conventional diesel fuel. This test was conducted on a single-cylinder diesel engine at 800, 1200, 1600, 2000, and 2400 rpm, then measured and recorded the values. The experimental results showed that torque, brake power and brake thermal efficiency of the engine using Yang oil showed average increased by 5.22%, 5.38% and 4.27%, respectively and brake specific fuel consumption of the engine using Yang oil showed an average decreased by 6.27% compared with those from diesel. The exhaust gas emission of engine using Yang oil were higher than diesel; CO, CO2 and NOx emissions increased slightly by 0.3% Vol., 2.02% Vol. and 18.80 ppm, respectively

Performance and Emission Characteristics of a Single-Cylinder Diesel Engine Fueled with Yang (Dipterocarpus alatus) Oil

846-849The objective of this study was to determine the performance and emission of diesel engine using Yang (Dipterocarpus alatus) oil compared with conventional diesel fuel. This test was conducted on a single-cylinder diesel engine at 800, 1200, 1600, 2000, and 2400 rpm, then measured and recorded the values. The experimental results showed that torque, brake power and brake thermal efficiency of the engine using Yang oil showed average increased by 5.22%, 5.38% and 4.27%, respectively and brake specific fuel consumption of the engine using Yang oil showed an average decreased by 6.27% compared with those from diesel. The exhaust gas emission of engine using Yang oil were higher than diesel; CO, CO2 and NOx emissions increased slightly by 0.3% Vol., 2.02% Vol. and 18.80 ppm, respectively

Experimental and numerical study of the solidification process in saturated porous media: Influence of the solid particle, types and freezing temperature

This research conducted an experimental and numerical study of the solidification process of a water saturated porous medium. The experiments were conducted in a rectangular test cell cooled from the lateral walls to obtain quantitative temperature distribution and solidification interface motion. Solid glass and steel particles were used as the porous medium and distilled water was the phase-change material. A one-dimensional mathematical model considered heat conduction as the only mode of heat transfer in both the frozen and unfrozen layer. A comparison of the experimental data with numerical predictions of the interface position and temperature distribution showed good agreement and thus confirmed the proposed mathematical model for a system of glass particles and water. For a system of steel particles and water, the computed results give the same trends as the experimental data

Photo-thermo-mechanical model for laser hair removal simulation using multiphysics coupling of light transport, heat transfer, and mechanical deformation (case study)

The mathematical model has become one of the tools for prediction to assist physicians and specialists with hair laser removal in dermatology. This paper proposes a model that comprehensively predicts optical, thermal, and mechanical responses within the skin during laser hair removal to determine optimal therapeutic conditions and prevent skin tissue damage. This research highlighted developing a mathematical model using multiple physics of light transport, heat transfer, and mechanical deformation. The present mathematical model is resolved using the 2D axisymmetric finite element method (FEM) with optical, thermal, and mechanical properties to characterize the laser intensity, temperature distribution, mechanical stress, and displacements within skin tissue. The comparison of the simulated results in laser wavelengths of 595 nm, 800 nm, and 1064 nm is also provided. The results revealed that laser deposition with skin tissue depends on the wavelength and optical diffusion coefficient. Applying the 1064 nm performs the best treatment outcome for hair laser removal. In contrast, 595 nm and 800 nm might lead to adverse pain sensations. The high temperature caused an increase in mechanical stress and displacement. The results of this study indicate that laser therapy has certain limitations that must be considered

Comparative analysis of RADAR vs. conventional techniques for AVF maturation in patients with blood viscosity and vessel elasticity-related diseases through fluid-structure interaction modeling: Anemia, hypertension, and diabetes.

PurposeThis study aims to compare two surgical techniques, the standard Vein-to-Artery and the newer Artery-to-Vein (Radial Artery Deviation And Reimplantation; RADAR), for enhancing the success of Arterio-Venous Fistula maturation in end-stage renal disease patients. The impact of diseases like anemia, diabetes, hypertension, and chronic kidney disease were considered. The goals are to advance Arterio-Venous Fistula (AVF) surgery, improve patient outcomes, and contribute to evidence-based surgical guidelines.MethodsFluid-structure interaction modeling was employed to investigate how hemodynamic and mechanical stresses impact arteriovenous fistula maturation, with a particular focus on the role of wall shear stress in determining maturation outcomes. The critical threshold for vessel injury was identified as wall shear stress values exceeding 35 N/m2, while stenosis formation was projected to occur at levels below 1 N/m2. This work introduced a novel approach by considering disease-related factors, including blood viscosity (anemia), and vessel elasticity (diabetes, hypertension, and chronic kidney diseases), which directly influence hemodynamics and the generation of wall shear stress. Furthermore, the model was designed to incorporate varying thicknesses and elasticities for both the vein and artery, accurately representing authentic vascular anatomy.ResultsThe RADAR technique has demonstrated superior performance compared to the standard technique by providing appropriate wall shear stress in critical regions and minimizing the risk of wall damage. Its use of a thicker vessel also reduces the risk of vessel injury, making it particularly effective for patients with Chronic Kidney Disease (CKD), hypertension, anemia, and diabetes, ensuring optimal blood flow and fewer complications. However, there are minor concerns about stenosis formation in hypertension and anemia cases, which could be mitigated by adjusting the anastomosis angle to be lower than 30°.ConclusionDiabetes and hypertension have significant physiological effects that increase the risks associated with arteriovenous fistula maturation. The anemic condition resulting from CKD may help reduce vessel injury but raises concerns about potential stenosis formation. Despite these co-morbidities, the RADAR technique has demonstrated its ability to induce more favorable hemodynamic changes, promoting arteriovenous fistula maturation

การศึกษาการแพร่กระจายความเข้มข้นของสารพิษที่ได้รับอิทธิพลจากความเร็วการไหลของน้ำในแม่น้ำและคลองที่ไหลมาบรรจบกันNumerical Study of a Combined Fluid Flow and Pollutant Concentration Dispersion in a Confluent River and Canal

ปัญหามลพิษเป็นปัญหาที่สำคัญ และส่งผลต่อการดำรงชีวิตของมนุษย์ ไม่ว่าจะเป็นมลพิษทางอากาศ หรือมลพิษทางน้ำในกรณีของมลพิษทางน้ำ ถ้าหากน้ำไม่สะอาด อาจส่งผลต่อน้ำสำหรับการบริโภค การอยู่อาศัยของสัตว์น้ำ และการประมง นอกจากนี้ยังส่งผลทางอ้อมโดยส่งกลิ่นเหม็นรบกวนได้ ในงานวิจัยนี้ศึกษาการแพร่กระจายความเข้มข้นของสารพิษที่ถูกปล่อยลงสู่คลองและไหลต่อไปยังแม่น้ำ ซึ่งถูกจำลองมาจากลักษณะภูมิประเทศจริงในประเทศไทย การวิเคราะห์และคำนวณจากสมการความต่อเนื่อง สมการโมเมนตัม และสมการการแพร่กระจายความเข้มข้นของสารด้วยโปรแกรมคอมพิวเตอร์ที่อยู่บนพื้นฐานของระเบียบวิธีไฟไนต์เอลิเมนต์ (Finite Element Method; FEM) ในงานวิจัยศึกษาถึงผลกระทบของความเร็วการไหลต่อการแพร่กระจายความเข้มข้นของสารพิษ ที่ความเร็วการไหลของน้ำในคลองที่มีค่า Reynold Number 8.3 × 104, 1.2 × 105 และ 1.7 × 105 และความเร็วการไหลของน้ำในแม่น้ำที่มีค่า Reynold Number 2.15 × 105, 4.3 × 105 และ 8.6 × 105 จากผลการวิจัยพบว่าโดยทั่วไปแล้วความเร็วการไหลในแม่น้ำสูงจะทำให้ความเร็วการไหลในคลองสูงขึ้น และความเร็วการไหลในคลองสูงจะทำให้ความเร็วการไหลในแม่น้ำสูงขึ้นเช่นเดียวกัน เพราะฉะนั้นแล้วในกรณีที่มีความเร็วการไหลสูงจะทำให้ความเข้มข้นเฉลี่ยของสารพิษเพิ่มขึ้นอย่างรวดเร็วและมีค่าสูง แต่สามารถลดความเข้มข้นเฉลี่ยได้รวดเร็วเช่นเดียวกัน ยกเว้นบางกรณีที่ความเร็วการไหลในคลองและแม่น้ำต่ำมากทำให้ค่าความเข้มข้นเฉลี่ยสูงขึ้น และบางค่าความเร็วทำให้เกิดการปะทะกันของน้ำที่จุดบรรจบกันของคลองและแม่น้ำส่งผลให้สารพิษสะสมบริเวณนั้นเป็นปริมาณมากและความเข้มข้นเฉลี่ยเพิ่มสูงขึ้นผลจากงานวิจัยนี้สามารถนำไปพัฒนาและประยุกต์ใช้กับแบบจำลองอื่นๆ หรือปัญหาที่คล้ายคลึงกันได้ เพื่อประโยชน์ในการจัดการปัญหาด้านมลพิษThe problems of air pollution and of water pollution are serious and harmful to human beings and other living organisms as contaminated water and pollution can affect human life, aquatic organisms and fisheries. Besides polluted water has long been recognized as an indirect cause of foul odors. This study investigates concentrations and dispersion of toxic pollutants released into a river and a canal. A model is simulated from the real geography of Thailand. Our study involves analyzing and calculating the continuity equation, momentum equations and species concentration dispersion equation based on the finite element method (FEM). This research focuses on the effects of inlet velocities on the concentration dispersions. The Reynold number of inlet velocities in the canal are 8.3 × 104, 1.2 × 105 and 1.7 × 105, and the Reynold number of inlet velocities in the river are 2.15 × 105, 4.3 × 105 and 8.6 × 105. Generally, the velocity of the canal increases when the inlet velocities of the river increases. Also, river velocity generally increases when the inlet velocities in the canal increase. Therefore, high flow velocity has a major impact on enhanced speed, elevated pollutant concentrations. Meanwhile concentrations of toxic substances can be reduced rapidly. In certain cases, the flow velocities in canals and rivers are very low, resulting in higher average concentrations. Moreover, flow velocities can cause collisions at the confluence, resulting in high concentrations of toxic substances and increased average pollutant concentrations. The research findings should be further developed and applied to other types of models or similar issues for effective pollution control and management