Control of instabilities in non-Newtonian free surface fluid flows

Free surface flows in inclined channels can develop periodic instabilities that are propagated downstream as shock waves with well-defined wavelengths and amplitudes. Such disturbances are called roll waves and are common in channels, torrential lava, landslides, and avalanches. The prediction and detection of such waves over certain types of structures and environments are useful for the prevention of natural risks. In this work, a mathematical model is established using a theoretical approach based on Cauchy's equations with the Herschel-Bulkley rheological model inserted into the viscous part of the stress tensor. This arrangement can adequately represent the behavior of muddy fluids, such as water-clay mixture. Then, taking into account the shallow water and the Rankine-Hugoniot's (shock wave) conditions, the equation of the roll wave and its properties, profile, and propagation velocity are determined. A linear stability analysis is performed with an emphasis on determining the condition that allows the generation of such instabilities, which depends on the minimum Froude number. A sensitivity analysis on the numerical parameters is performed, and numerical results including the influence of the Froude number, the index flow and dimensionless yield stress on the amplitude, the wavelength of roll waves and the propagation velocity of roll waves are shown. We show that our numerical results were in agreement with Coussot's experimental results (1994).

Information flows and environments in business contexts: the meat sector case of Salmanca/Spain

Organizational environments are related to hierarchic levels existing in a determined organization, and they influence in the formal and informal flows origin and in their monitoring and/or extinction. Informational environments are a result of organizational environments, of which focus is information and knowledge. Information flows are a fundamental element to informational environments, in a way that there´s no informational environments if there´s no information flows. Informational flows are natural reflections from their environments, in terms of content and in the way they occur. This qualitative and quantitative research was developed in three stages, in a way to allow the comprehension of the phenomena related to information and knowledge environments and information flows that occur in the meat sector from the Province of Salamanca, Spain. We used Laurence Bardin´s ‘Analysis of Content’, more specifically the ‘Categorical Analysis’ technique to data analysis. As data collection procedure we accomplished a field research, applying a questionnaire as an intentional sample of the meat industries segment from the Province of Salamanca, Spain. From data tabulation and analysis, we infer that information environments and flows are relevant to these companies business development, as well as we emphasized the need of information and knowledge management deployment, in a way to insure organizational processes quality, industrial chain production and companies competition to conquer potential markets.

Pressure distribution on the frontal disk for turbulent flows in a radial diffuser

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Experimental setup for measuring roll waves on laminar open channel flows

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)