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This paper presents the results of an experimental study of mixing fluid flows of different temperatures in a T-junction. The experiments were performed with liquids having substantially different physical properties. The distribution fields of the average and fluctuation temperatures on the surface of the wall of the T-junction, and the structure of the temperature field in the mixing region of cold and hot fluid flows were obtained. [ABSTRACT FROM AUTHOR]

This study aims to investigate entropy generation for flow of three different nanofluids in a chaotic minichannel. Fluid particles in this channel move in chaotic trajectories, which can intensify the flow mixing. The results show that the contribution of heat transfer to entropy generation is greater than that of friction. With increasing the concentration, thermal entropy generation decreases for the alumina–water and Cu–water nanofluids, while intensifies for the magnetite–water nanofluid. With increase in Reynolds number for all nanofluids, thermal entropy generation decreases while frictional entropy generation increases. With the concentration increment, frictional entropy generation rate has an ascending trend for the alumina–water and magnetite–water nanofluids, while has a descending trend for the Cu–water nanofluid. Moreover, as Reynolds number increases from 50 to 200 at concentration of 1%, total entropy generation reduces 66.25%, 65.9% and 68.9% for the magnetite, alumina and Cu nanofluids, respectively. Based on the second law of thermodynamics, the Cu–water nanofluid is a more appropriate coolant owing to smaller total entropy generation. Moreover, use of the Cu–water and alumina–water nanofluids is more suitable at greater concentrations, while employing the magnetite–water nanofluid is only recommended at low concentrations. [ABSTRACT FROM AUTHOR]

Normal pressure hydrocephalus (NPH) is an intracranial disease characterized by an abnormal accumulation of cerebrospinal fluid (CSF) in brain ventricles within the normal range of intracranial pressure. Most NPH in aged patients is idiopathic (iNPH) and without any prior history of intracranial diseases. Although an abnormal increase of CSF stroke volume (hyper-dynamic CSF flow) in the aqueduct between the third and fourth ventricles has received much attention as a clinical evaluation index in iNPH patients, the biomechanical effects of this flow on iNPH pathophysiology are poorly understood. This study aimed to clarify the potential biomechanical effects of hyper-dynamic CSF flow through the aqueduct of iNPH patients using magnetic resonance imaging-based computational simulations. Ventricular geometries and CSF flow rates through aqueducts of 10 iNPH patients and 10 healthy control subjects were obtained from multimodal magnetic resonance images, and these CSF flow fields were simulated using computational fluid dynamics. As biomechanical factors, we evaluated wall shear stress on the ventricular wall and the extent of flow mixing, which potentially disturbs the CSF composition in each ventricle. The results showed that the relatively high CSF flow rate and large and irregular shapes of the aqueduct in iNPH resulted in large wall shear stresses localized in relatively narrow regions. Furthermore, the resulting CSF flow showed a stable cyclic motion in control subjects, whereas strong mixing during transport through the aqueduct was found in patients with iNPH. These findings provide further insights into the clinical and biomechanical correlates of NPH pathophysiology. [ABSTRACT FROM AUTHOR]

Hot air from the cooling zone of a continuous kiln is available at the end of the corresponding firing zone. It can be used again with the application of special injectors. 3D simulations in a domain containing injector nozzles are carried out to evaluate the temperature distribution inside the continuous kiln in case of using the hot air which comes from the cooling zone. The roller hearth kiln is taken as a computational domain in this study. Parameters referring to the direction of the burner streamline, the quantity of the air sucked and the effect of the cone length are studied. The temperature distribution at the outlet is determined in case of fixing the burner against or along the direction of the main flow. It is shown that the maximum air velocity at the outlet of the burner cone is about 90m/s. The upstream model temperature distribution is found better than the downstream one. It is also suggested that a burner with longer outlet duct can protect the product from direct exposure to the flame. [ABSTRACT FROM AUTHOR]

Blind-tee pipes are often employed in process piping systems used in offshore and subsea oil and gas industry. The objective of the present study is to investigate the effects of blind-tee length, end-structure shape and flow velocity on the mixing condition inside blind-tee pipes. Three-dimensional numerical simulations are performed for the laminar flows in the pipes with blind-tee length varying from 1 D to 5 D at Re = 500, 1000, 1500 and 2000. Spherical and flat end-structure shapes are also investigated for the blind-tee section. Firstly, flow simulations in a straight pipe are performed, and the numerical results are compared with the analytical solutions. Then, the computed velocity profiles are used as the inlet velocity for the simulations of blind-tee pipes. Flow characteristics both inside and downstream the blind-tee section are numerically studied by analyzing the streamlines, pressure contours and velocity profiles. The results reveal that a higher inlet velocity and a blind-tee length no more than 3 D can achieve a better mixing condition for the fluid flow in blind-tee pipes; while stagnant flows are more prone to occur towards the end of the blind-tee section at low velocities with the length longer than 3 D , leading to potential fluid deposition in blind-tee pipes. • Laminar flow can form 1 to 3 flow circulations in the blind-tee section with blind-tee length B T L ≤ 5 D. • With an increase in BTL or a decrease in Reynolds number, more flow circulations are generated with lower velocity and therefore increases the possibility of stagnant flow at the blind-tee end. • The maximum size of the first circulation created by laminar flow in the blind tee is around 3D. • A higher flow velocity and B T L ≤ 3 D can achieve a better mixing condition in blind-tee pipes. [ABSTRACT FROM AUTHOR]