Natural Convection heat transfer from a horizontal hollow cylinder having annular fins on the outer surface has been studied numerically. The constant temperature boundary condition was applied at the inner surface of the hollow cylinder. Boussinesq approximation was used with steady and laminar flow. For simulation ANSYS FLUENT was used to solve the discretized system and three dimensional model was prepared in SOLIDWORKS. The present investigation showed us that the analytical solution and numerical solution for unfinned hollow cylinder are very accurate and the cases with fins from 4 to 20 were solved by simulated showing us the pictorial representation of temperature plume and velocity vectors. The plots are shown comparing different thermal parameters such has heat flux, total heat transfer, Rayleigh number, Nusselt number and effectiveness of the system with fins with respect to the number of fins attached to the hollow cylinder.
Mixing at microscales is purely governed by the diffusion mass transport phenomenon, which is a time‐consuming process requiring a prolonged length of the microchannel to obtain desired results. The present study proposes a novel three‐dimensional helical micromixer (TDHM) with a rectangular cross‐section to achieve splendid mixing performance within a short distance contrary to the simple T‐micromixer (STM). A thorough numerical investigation of mixing performance and fluid flow patterns has been conducted using the continuity, species transport, and the Navier–Stokes equations with Newtonian and non‐Newtonian fluid at a wide range of Reynolds number (0.2–320) and mass flow rate (0.00005–0.091 kg/h), respectively. Blood is selected as the non‐Newtonian fluid, and its rheological characteristics are numerically captured by implementing the Carreau–Yasuda model, whereas water is used to study mixing with the Newtonian fluid. At Re = 2, the mixing index of TDHM is 40. 5% more than that of the STM with water as the working fluid, whereas for blood, it is 34.3%, and thus, it was concluded that the TDHM gives much better performance at much less axial distance than that of the STM at all values of the Reynolds number and flow rates considered in the study. Therefore, TDHM can be utilized for various biomedical, chemical, and biochemical applications.
New designs of mechanical ventilators require extensive testing before utilizing the ventilator on a patient. Test lungs are commonly used to understand the behavior of new designs of ventilators and the lung mechanics. The current study aims to develop a numerical model of dual test lungs utilizing the partitioned fluid-structure interaction (FSI) approach and test it against the available experimental data of volume-controlled ventilation. Two breathing rates of 12 and 18 bpm were studied at two different tidal volumes of 500 and 600 ml for spontaneous breathing. It is found that with an increase in the compliance (tidal volume/pressure rise) of the lung, the peak pressure rise inside the test lung decreases irrespective of the breathing rate. The maximum average pressure of 44.73, 27.45, and 14 cm H 2 O is observed for static lung compliances of 10, 21 , and 39 ml/cm H 2 O, respectively at a tidal volume of 600 ml.Similarly, the maximum von-misses stress was higher (498 kPa) for the lung with lower compliance (10 ml/cm H 2 O) as compared to the lung with higher compliance (39 ml/cm H 2 O) at the end of inspiration. This study forms a basis for using computational methods to model simple lung simulators that can effectively investigate the lung mechanics for both spontaneous and ventilated breathing. Thus, it can be utilized as a reference to test novel designs of mechanical ventilators.
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