Improvement of experimental apparatus dedicated to pulsating phenomena study in mudflows: experimental validation of cutting frequency

Abstract

This proposal arises from the motivation to investigate further the non Newtonian hyperconcentrated fluid flows with free surface, as part of "Natural" Disasters, specifically mudflows.Seeking greater understanding of disasters and more complete mathematical models, RMVP Team (Reologia de Materiais Viscosos e Viscoplásticos) of College of Engineering of Ilha Solteira at Unesp has posed a challenge to train its researches on the perception and acquisition of skills on this subject under three aspects: Interpretative frameworks establishment, based on studies of Social Sciences, Risk Analysis and Mechanistic Approach of mudflows through physical and numerical modeling.In the context of the mechanistic approach (focus of this proposal), it has the scientific agents to better understand the "natural" phenomena, causes of disasters, and promote the creation of more effective tools and methodologies in its forecast. In this perspective, RMVP Team has embarked efforts in developing mathematical, numerical and experimental models of mudflows phenomenon. In addition, the researchers are studying the mechanisms of generation and control and characteristics of roll waves present eventually in mudflows.Right away, it is noteworthy that if the mudflows and their potential fronts are responsible for the destruction of infrastructures, as well as loss of life. Its consequences can be amplified in the presence of instabilities (roll waves) on the free surface. Such waves in the literature are called roll waves that propagate with amplitude and celerity well defined by a dynamic extremely linked to the mud rheology.With a regard to the experimental work on roll waves, mainly in non-Newtonian rheology to the presence of yield stress, there is still significant gap in the literature. In this sense, the main objective of this project is to conduct experiments with non-Newtonian rheology using the existing experimental apparatus at Unesp by implementing improvements in the flow disturbance system and also in the measurement system of the free surface, making it possible to generate roll waves stabilized and measure their properties (amplitude and period), with greater accuracy. CONTROL AND EXPERIMENTAL VALIDATION of the cutoff frequency, proposed in this project, in the generation process of roll waves, is original, which is expected to contribute for the full understanding of the phenomenon. (AU)