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While magnetic resonance velocimetry (MRV) has been used in technological flow studies for over 30 years, it has not yet reached the levels of usage as more traditional experimental techniques such as particle image velocimetry or laser Doppler anemometry. This work involves a relatively simple U-bend geometry with complex three-dimensional turbulent flow characteristics which was shared with four research groups, including a combined effort from the U.S. Military Academy/Stanford University, and teams from Hanyang University, the University of Rostock, and the Mayo Clinic. The geometry—including upstream flow development—was shipped between groups with nominally similar experimental conditions, and the acquired data are presented including both two- and three-dimensional comparisons. In addition, details on how each team conducted the MRV experiments are provided, with each team using a different set of procedures and hardware. The results are remarkably similar, with only a few variations at the flow regions with the highest in-plane velocity gradients showing differences outside the combined uncertainty of the results. [ABSTRACT FROM AUTHOR]

Vortex-induced vibration (VIV) based energy conversion is a promising methodology to generate electricity by utilizing the flow energy neglected and eventually dissipated in nature, as the power generation process is sustainable and free from emission of pollutants. In this vein, micro-scale energy convertors driven in low-Reynolds-number flows have caught the attention for engineering applications. As the performance of the convertors highly depends on the acting forces or VIV responses, VIV amplifications are necessary to elevate the power output or energy conversion efficiency toward a level of engineering practicability. The attachment of a pair of bumps on an elastically mounted circular cylinder was demonstrated as an effective way to elevate the energy output for VIV-based energy convertors. However, most of relevant studies were conducted for turbulent flows as high-capacity energy convertors are of significant interest for direct engineering applications. On the other hand, the effects of the bumps on the energy transfer have rarely been studied for low Reynolds number flows. This paper then aims to quantify the effects of the circumferential locations of a pair of bumps on the energy transfer ratio in a single circular cylinder VIV configuration for Reynolds number 150. The circumferential location of the bumps is optimized under the synchronization condition, and this is compared with the plain cylinder VIV configuration; the energy transfer ratio is appreciably elevated when the bumps are placed at θ = 60 or 75-degree. [ABSTRACT FROM AUTHOR]

Abstract: A slot coating process has been recently applied to the production of electric circuits due to its fast production rate and low cost. The prediction of minimum coating thickness or coating stability has been performed by using a viscocapillary model. However, the results are inaccurate for a high speed coating because it neglects inertia effects arising in the high speed coating condition. Thus, we modified the viscocapillary model to propose an inertia-capillary model that includes the inertial effects. As a result, this new model can be applicable to a Reynolds number of an order higher than the viscocapillary model. [Copyright &y& Elsevier]

Abstract: A mathematical model is proposed to evaluate the frosting behavior of a fin–tube heat exchanger under frosting conditions. Empirical correlations of the heat transfer coefficients for the plate and tube surfaces and a diffusion equation for the frost layer are used to establish the model. The correlations for the heat transfer coefficients, derived from various experimental data, were obtained as functions of the Reynolds number and Prandtl number. The proposed model is validated by comparing the numerical results with experimental data for the frost thickness, frost accumulation, and heat transfer rate. The numerical results agree well with the experimental data. It is also found that this model can be applied to evaluate the thermal performance of a common fin–tube heat exchanger under frosting conditions. [Copyright &y& Elsevier]

The effects of wall roughness were examined experimentally for two different rough-wall cases involving flow over a ramp with separation and reattachment. For these cases, the roughness Reynolds number was matched at two different momentum thickness Reynolds numbers. Both flow conditions were fully rough. The effect of increasing the wall roughness was to increase the friction velocity and increase the separation region size. The two rough-wall cases produced different size separation regions and different friction velocity values. This shows that the roughness Reynolds number is not sufficient to characterise the roughness effects. Another parameter such as the ratio of the roughness height to the boundary layer thickness is also necessary. In both cases, the outer layer turbulence was mainly affected by the change in the friction velocity. [Copyright &y& Elsevier]