Three-dimensional CFD simulations are carried out to investigate heat transfer and fluid flow characteristics of a four-row plain fin-and-tube heat exchanger using the Commercial Computational Fluid Dynamics Code ANSYS CFX 12.0. Heat transfer and pressure drop characteristics of the heat exchanger are investigated for Reynolds numbers ranging from 400 to 2000. Fluid flow and heat transfer are s...

We present experimental data for the static or breakloose friction for lubricated elastomer contacts, as a function of the time of stationary contact. Due to fluid squeeze-out from the asperity contact regions, the breakloose friction force increases continuously with the time of stationary contact. We consider three different cases: (a) PDMS rubber balls against flat smooth glass surfaces, (b)...

Predictions of the gas temperature and pressure profiles are vital to the design and operation of gas transmission lines. Available analytical methods for the calculation of these profiles are evaluated and a numerical framework for the rigorous calculation has been developed. The predictions from both the analytical and numerical procedure have been compared to field data from the Iranian Gas ...

[1] In the study of natural rivers, accurate conveyance estimation is challenging because of complex cross-sectional geometry and variable flow resistance. The aim of this study was to investigate the additional friction factor due to lateral momentum transfer at the interface of vegetated and nonvegetated channel parts in two rivers: (1) the Rhine River, a large dredged river with partially ve...

We develop a simplified model to predict the frictional behaviour of the contact between the surfaces of a rotary shouldered thread connection in the make-up process of premium tubular connections as used in the oil pipeline business. A classic wear model is applied at the scale of the surface asperities to predict the evolution of friction between initially shot-peened surface and bronze plate...

in order to evaluate intercropping of barley (hordeum vulgare) and vetch (vicia vilosa ler ssp. desycarpa), two field experiments were conducted on the farm of the university of tehran, karaj, iran in 2004 and 2005. a split plot experiment based on randomized complete block design (rcbd) with four replications was used in this study. nitrogen was the main factor (0, 45 and 90) and sub plot fact...

The mixture of factor analyzers model, which has been used successfully for the model-based clustering of high-dimensional data, is extended to generalized hyperbolic mixtures. The development of a mixture of generalized hyperbolic factor analyzers is outlined, drawing upon the relationship with the generalized inverse Gaussian distribution. An alternating expectation-conditional maximization a...

The space Brayton nuclear reactor system usually adopts the helium–xenon gas mixture (He–Xe) as working fluid. flow of He–Xe in micro channel regenerator is generally laminar. Since properties are significantly different from those common pure gases, impact this difference on laminar and heat transfer needs to be evaluated. In present study, numerical simulations convective for helium, nitrogen...

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