Abstract

Concrete is the main material used in the construction industry not only for the ability to produce infinite variety of shapes for precast forms and for its characteristics of high resistance to compression, but primarily for their low manufacturing cost. Nonetheless, the production by mixing cement, fine aggregate, coarse aggregate and water, using natural raw materials such as stone, sand and water, despite being plentiful, represent the consumption of millions of tons of natural resources. Thus, the continuous search for new solutions is fundamental in order to not only further lower the manufacturing costs of this essential component in construction, but also to seek alternative materials, those of origin in processes of sustainability

Abstract

The advance in research and development will make the deployment of automated vehicles a reality in the near future. At the initial stage, semi-automated vehicles with the capability to follow each other automatically in the same lane will coexist with manually driven vehicles on the same roadway system. A number of safety and human factor issues need to be resolved before such mixing becomes possible. In this paper we analyze the effect of mixing on capacity and stability of vehicle following. We found that capacity may not always increase with the percentage of semi-automated vehicles because the intervehicle spacing has to account for driver reaction times during stopping. Semi-automated vehicles will attenuate the "slinky effects" without affecting the total travel time. © 1998 Society of Automotive Engineers, Inc. "p"Conference code: 90134 Cited By :2

Abstract

In this work original experimental data and a simplified model for the prediction of pressure drops in pipelines equipped with static mixers are presented. The experimental data clarify the effect of the element length and of the relative position between two consecutive elements on the pressure drop. A significant reduction of the pressure drop is obtained by shortening the element length, while the relative position between consecutive elements has a minor importance. The experimental data are discussed and adopted for testing the proposed model reliability under various physical and geometrical conditions. The results show that the model, which is also compared with the available literature correlations, can be confidently applied to standard static mixers as well as to unconventional static elements arrangement, since it reliably accounts for the pressure drop variations due to changes in the geometrical configuration. The analysis is focused on static mixers for turbulent flow in pipelines, in particular the corrugated plate mixers.

Abstract

This work is aimed at investigating the capability of a fully predictive computational fluid dynamics (CFD) approach to catch the main features of the liquid flow in pipelines equipped with corrugated static mixer inserts. The simulations are based on the numerical solution of the Reynolds averaged Navier−Stokes equations on the three-dimensional domain closely representing the static mixer geometry. As a benchmark, literature experiments on a laboratory scale SMV mixer were considered and the simulation results obtained at different locations were compared with relevant velocity and tracer concentration data. The effect of the turbulence modeling, the near-wall treatment, and the numerical approximations on the accuracy of the results is discussed. The results analysis demonstrated that the selected CFD model can be reliably adopted to evaluate the velocity field and the mixing performances of turbulent flows in static mixers for design and optimization purposes. On the other hand, the application of the same model to an industrial scale corrugated plate mixer highlighted the effects of the distributor geometry and of the distance between consecutive elements on the mixing of two miscible liquids.

Abstract

LIXIL Co. handles a wide range of water-related products such as showers, toilets, baths, and kitchens. The fluid behavior control is a key technology for developing of these products. Therefore, the numerical simulation with CFD plays an important role in product and technical development. The flow of water in showers has been simulated with the finite volume method (FVM). However, the simulation with fine droplets such as in a shower needs a lot of computational cost. To deal with this problem, MPS particle method [1] has been introduced to take an advantage of enabling for simulating such as splashing, droplets, and mixing. In this paper, the MPS particle method is studied to simulate the shower head design because it is the first use case for simulating the spout, coupling with mechanism analysis. Because computational efficiency is also an important factor for the product development, the computational performance on GPU against multi-CPU for the MPS particle method is also discussed.