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Slug flow is a two-phase fluid flow pattern, characterized by a series of liquid slugs dispersed by relatively large air bubbles. Air bubbles produced and trapped during the slug flow phenomenon conduct to interruption in flow which induces pressure and velocity fluctuations. These effects have destructive circumstances in conduits and conveyance structures. This paper deals with studying numerically two-phase flows using computational fluid dynamic (CFD) techniques performed in OpenFOAM (an open source software) by interFoam solver. Most of the previous concerning studies on slug flow were performed in micro-channels with small scales in which the expansion of the air bubbles was negligible. By contrast, we investigated the systems with large pressure drops which conduct to abrupt increases on the volume of air phase. The slug flow phenomenon could be created by introducing air and water with different velocities at inlet of a culvert with air to water velocity ratio varied from 1.1 to 34. First, this study focused on temporal and spatial variations of pressure and velocity along the culvert. After that, by dimensional analysis, the nondimensional parameters influencing the slug flow phenomenon are extracted and analyzed. Finally, different strategies for reducing the destructive effects of slug flow, including the shape and location of ribs, are evaluated and the best strategy is proposed.

A frequent problem in computer aided mechanical design is the construction of arbitrarily-shaped ribs and beads on surfaces, to increase their rigidity or for aesthetic reasons. We improve upon a previous mathematical approach for defining such ribs and beads, based on using so-called extension functions to define a deformation matrix, which is then applied to the underlying shape. Our improvements offer important practical advantages: firstly, by use of cosine extension functions, we get a greater control over, and flexibility of, rib shape, including the possibility of repeating ribs; secondly, we can directly control the spine curves. We give experimental results to demonstrate that the method is simple and intuitive, has low computational cost, and is potentially useful for computer aided design, computer graphics and other applications.

Ribbed plate construction is a shallow foundation system known to provide stiff planar substructure capable of transferring large vertical loads more uniformly to the subgrade. One special class of ribbed mat foundations has been patented in Indonesia and is called the spider net construction (Konstruksi Pondasi Sarang Laba-Laba/KSLL). KSLL can function as pavement or foundation system and consists of rib, plate and infill materials. This study, first discusses the importance of different components in ribbed mat foundation and then develops the design strategy to apply it for airport and highway pavements. The effectiveness of ribbed mat foundation in comparison with the conventional rigid pavement construction is also elaborated.