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Numerical analysis of heat transfer in human head
Abstract
An investigation of heat transfer in human head is carried out by using finite element method. The head is modeled with different tissues having varying physical properties. The current work is focused to simulate the effect of various physical and geometrical parameters such as ambient temperature, heat transfer coefficient and variation in the thickness of different tissue layers of human head. The effect of presence of hair on human head is also investigated. It is found that the deep brain temperature remains almost constant whereas a small variation occurs in the other layers with respect to varying environmental and geometrical parameters.
Citation: Kamangar, S., Khan, M.A., Badruddin, I.A. et al. Numerical analysis of heat transfer in human head. J Mech Sci Technol 33, 3597–3605 (2019). https://doi.org/10.1007/s12206-019-0654-x
A Computational Study of Curvature Effect on the Coronary Diagnostic Parameters in Stenosed Coronary Artery
A Computational Study of Curvature Effect on the Coronary Diagnostic Parameters in Stenosed Coronary Artery
Abstract
The presence of downstream curvature can affect the blood flow in artery leading to complicated hemodynamics. Thus, the current study is focused to explore the effect of downstream curvature of artery wall on the severity of stenosis by assessing the Fractional Flow Reserve, Lesion Flow Coefficient and Pressure Drop Coefficient under various downstream curvature angles in coronary artery. Computational fluid dynamics (CFD) of hyperemic flow in curved arteries was performed with various downstream curvature angles (0O 300 600 900 and 1200) subjected to three different blockage (70%, 80% and 90%) area stenosis (AS). It is discovered that flow resistance caused by stenosis increases further due to the downstream curvature of artery. The FFR decreased by 5.4%, 8.6% and 13.1% for 70%, 80%, and 90%AS respectively as the downstream curvature of artery increased from 00 to 1200. The increase in CDP and decrease in LFC was found as the downstream curvature increased from 00 to 1200. The differences in diagnostic parameters FFR, CDP and LFC shows that misinterpretation could be possible while evaluating the functional significance of stenosis, so the downstream curvature must be contemplated while evaluating the importance of stenosis as an additional parameter for FFR.
Citation: Badruddin, I. A., Kamangar, S., Algahtani, A., Khan, M. A., N.J., S. A., Saleel, C. A., & Khan, T. Y. (2019). A Computational Study of Curvature Effect on the Coronary Diagnostic Parameters in Stenosed Coronary Artery.
Investigation of Coronavirus Deposition in Realistic Human Nasal Cavity and Impact of Social Distancing to Contain COVID-19: A Computational Fluid Dynamic Approach
Investigation of Coronavirus Deposition in Realistic Human Nasal Cavity and Impact of Social Distancing to Contain COVID-19: A Computational Fluid Dynamic Approach
Abstract
The novel coronavirus responsible for COVID-19 has spread to several countries within a considerably short period. The virus gets deposited in the human nasal cavity and moves to the lungs that might be fatal. As per safety guidelines by the World Health Organization (WHO), social distancing has emerged as one of the major factors to avoid the spread of infection. However, different guidelines are being followed across the countries with regards to what should be the safe distance. Thus, the current work is an attempt to understand the virus deposition pattern in the realistic human nasal cavity and also to find the impact of distance that could be termed as a safety measure. This study is performed using Computational Fluid Dynamics as a solution tool to investigate the impact of COVID-19 deposition (i) On a realistic 3D human upper airway model and (ii) 2D social distancing protocol for a distance of 0.6, 1.2, 1.8, and 2.4 m. The results revealed that the regional deposition flux within the nasal cavity was predominantly observed in the external nasal cavity and nasopharyngeal section. Frequent flushing of these regions with saltwater substitutes can limit contamination in healthy individuals. The safe distancing limit estimated with 1 m/s airflow was about 1.8 m. The extensive deposition was observed for distances less than 1.8 m in this study, emphasizing the fact that social distancing advisories are not useful and do not take into account the external dynamics associated with airflow.
M. Zuber et al., “Investigation of Coronavirus Deposition in Realistic Human Nasal Cavity and Impact of Social Distancing to Contain COVID-19: A Computational Fluid Dynamic Approach,” Comput. Model. Eng. Sci., vol. 125, no. 3, pp. 1185–1199, 2020. https://doi.org/10.32604/cmes.2020.015015
Heat transfer enhancement in multijet micropin fin heat sink. Numerical Heat Transfer, Part A: Applications, 1–20.
Heat transfer enhancement in multijet micropin fin heat sink. Numerical Heat Transfer, Part A: Applications, 1–20.
Abstract
The thermal performance of tiny heat sinks with liquid cooling is being studied in order to solve the issue of electronics cooling. Increasing thermal performance while lowering pressure drop and maintaining a constant substrate temperature is a difficult task. The purpose of this study is to harvest the useful features of combination of microjet and micropin fins and explore the influence of geometrical features on fluid structures and heat transfer. To comprehend and assess the performance of a multijet heat sink with a micropin fin, three-dimensional numerical simulation is used in this inquiry. The three parameters under consideration are, the ratio of the jet diameter to the pin fin diameter (α), which ranges from 1.5 to 6.0; the ratio of the jet diameter to the jet standoff distance (β), which ranges from 0.75 to 1.5; and the pin fin pitch is determined by the ratio of the pin fin diameter to the pitch length (λ), which ranges from 0.1 to 0.8. The grid independence test is done to ensure accuracy in numerical results. The numerical scheme is validated by comparing numerical results with that of experimental results from literature. The results obtained from numerical simulation are analyzed. It has been found that improving heat transfer is not just caused by expanding the contact surface area; fluid structure vortex generation also affects overall thermal performance. Better overall performance is produced at lower values of α, β and higher values of λ. The ideal design parameters are α = 1.99, β = 1.431, and λ = 0.699, according to the optimization of geometrical parameters using a radial basis neural network surrogate model and particle swarm optimization. The jet Reynolds number is found to have no significant impact on the overall performance.
Qidwai, M. O., Badruddin, I. A., Kamangar, S., Khan, N. Z., Khan, M. A., Khan, M. N. (2023). Heat transfer enhancement in multijet micropin fin heat sink. Numerical Heat Transfer, Part A: Applications, 1–20. https://doi.org/10.1080/10407782.2023.2294349
Black-Box Optimization for Engineering Systems with Score-Function Estimator
Black-Box Optimization for Engineering Systems with Score-Function Estimator
Abstract
Optimization of engineering systems is essential for efficient operation and enhanced lifespan of these systems. Owing to their complex designs, multiple design parameters, and their operation under stochastic conditions, optimization of such systems becomes difficult. The absence of a well-defined mathematical relation between the input and the output of such systems prevents the conventional gradient based methods from providing meaningful solutions. To optimize such problems, we use black-box optimization techniques. Multiple black-box optimization techniques have been developed, which have been shown to perform well for low and medium dimensional problems. ScoutND, a black-box optimization algorithm is shown to perform well for high dimensional problems as well as stochastic problems. The present work extends ScoutND to perform shape optimization of the PitzDaily problem, a test case problem in Computational Fluid Dynamics. We propose methods to perform Constrained and Unconstrained optimization of the PitzDaily problem. We perform optimization under stochastic and non-stochastic conditions. We compare the results of our shape optimization problem from ScoutND with other optimizers such as Nelder-Mead, SLSQP, COBYLA, and L-BFGS-B. We show that ScoutND successfully optimizes the problem for stochastic and non-stochastic conditions and outperforms all other optimizers in the case of stochastic conditions.
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