Research Article
Impact of Varying Thermal Conductivity and Viscosity on Natural Convection Flow Along a Vertical Flat Plate with Heat Conduction and Viscous Dissipation
Md. Al-Amin,
Md. Mahmud Alam,
Sree Pradip Kumer Sarker*
Issue:
Volume 13, Issue 6, December 2025
Pages:
148-161
Received:
19 April 2025
Accepted:
26 May 2025
Published:
9 December 2025
Abstract: This study examines how natural convection flow down a vertical flat plate is affected by varying viscosity and thermal conductivity, taking into account the effects of heat conduction and viscous dissipation. The fluid flow and heat transfer are described mathematically, accounting for temperature-dependent changes in thermal conductivity and viscosity. Using suitable boundary conditions, the governing equations—such as the momentum, energy, and continuity equations—are numerically solved. The impact of these changes on temperature distributions, velocity profiles, Nusselt number, and total heat transfer efficiency is the main focus of the analysis. The findings show that changes in thermal conductivity and viscosity have a major effect on the establishment of thermal boundary layers, heat transfer efficiency, and flow characteristics. The research was conducted to improve the comprehension and prediction of heat transfer processes in a variety of engineering applications by examining the effect of varying thermal conductivity and viscosity on natural convection flow along a vertical flat plate with heat conduction and viscous dissipation. Natural convection is essential in situations where heat transmission occurs without external mechanical aid, including cooling systems, electronic gadgets, and building ventilation. Researchers seek to create more precise models for predicting fluid flow and heat transfer behaviour under varying settings by examining these changes.
Abstract: This study examines how natural convection flow down a vertical flat plate is affected by varying viscosity and thermal conductivity, taking into account the effects of heat conduction and viscous dissipation. The fluid flow and heat transfer are described mathematically, accounting for temperature-dependent changes in thermal conductivity and visc...
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Research Article
Evaluation of Patient Dose from Chest Ct Examinations in Selected Diagnostics Centres in Abuja, Nigeria
Issue:
Volume 13, Issue 6, December 2025
Pages:
162-168
Received:
14 October 2025
Accepted:
27 October 2025
Published:
9 December 2025
Abstract: This study assessed patient radiation exposure from chest computed tomography (CT) examinations across three diagnostic centers (A, B, and C) in Abuja, Nigeria. A total of chest 60 CT scan records were retrospectively analyzed, and radiation dose parameters including weighted CT dose index (CTDIw), dose length product (DLP), and effective dose were evaluated. Technical factors such as tube current (mAs), tube voltage (kVp), pitch, and patient body weight were also collected to determine their influence on dose variations. The mean CTDIw values were 5.49, 5.88, and 7.42 mGy.cm for Centers A, B, and C, respectively, while the corresponding DLP values were 271.48 ± 183.2, 253.32 ± 120.4, and 437.16 ± 433.5 mGy·cm. Effective doses to the chest were 4.62, 4.31, and 7.43 mSv. Centers A and B demonstrated relatively optimized protocols, whereas Center C consistently reported higher radiation metrics. Technical and demographic data revealed higher mAs (220 ± 35), tube voltage (120 kVp), lower pitch (0.9), and higher mean body weight (78 ± 12 kg) in Center C compared with Centers A and B, accounting for its higher dose indices. Compared with international benchmarks, results from Centers A and B were consistent with European and Turkish diagnostic reference levels (DRLs), while Center C exceeded some international thresholds but remained within Nigerian DRL frameworks. These findings highlight the influence of patient and technical factors on dose variation and emphasize the need for protocol harmonization to optimize patient safety without compromising diagnostic quality.
Abstract: This study assessed patient radiation exposure from chest computed tomography (CT) examinations across three diagnostic centers (A, B, and C) in Abuja, Nigeria. A total of chest 60 CT scan records were retrospectively analyzed, and radiation dose parameters including weighted CT dose index (CTDIw), dose length product (DLP), and effective dose were...
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,
Idris Mustapha Mohammed
