ResumenSe desarrolló un modelo matemático a partir de la ecuación general de dispersión y se comparó con tres modelos tradicionales. Para obtener los datos experimentales se realizaron ensayos hidráulicos utilizando litio como trazador agregado de forma puntual en el influente de un Reactor Anaerobio de Flujo Ascendente de 518 litros, alimentado con agua residual de la ciudad de Maracaibo-Venezuela a tiempos de retención hidráulico teórico de 10, 8, 5 y 4 horas. Se tomó muestras en el efluente y al final del lecho y manto de lodo. Los mejores ajustes se lograron con el modelo propuesto con desviación media absoluta entre 5 y 33% y desviación media relativa entre -1,7 y -18%. En todos los casos, el número de dispersión fue mayor a 0.01 indicando que no existió flujo pistón en el reactor. Palabras clave: dispersión axial; modelo; trazador; inyección puntual; reactor de flujo ascendente Axial Dispersion Model for Continuous Flow Systems Adjusted Boundary Conditions AbstractIn this study a mathematical model was developed from a general dispersion equation, which was compared with three traditional models. Tracer tests were carried injected lithium as a pulse at the reactor influent. Several samples were collected in an Upflow Anaerobic Sludge Bed reactor o 518 liters to obtain the experimental data. The reactor was feeding from municipal wastewater of Maracaibo city, Venezuela. Several theoretical retention times were evaluated between 4, 5, 8 and 10 hours. Samples were taken at the final effluent and at the end of the sludge blanket and bed level. Best fits were obtained with the proposed model giving absolute mean deviation between 5.0 and 33% and relative mean deviation between -1.7 and -18%. In most of the studies the dispersion number was lower than 0.01 concluding that plug flow did not exist in the reactor.
A physical and a computational fluid dynamic (CFD) model (HYDRO-3D) were developed to simulate the effects of novel maturation pond configurations, and critical environmental factors (wind speed and direction) on the hydraulic efficiency (HE) of full-scale maturation ponds. The aims of the study were to assess the reliability of the physical model and convergence with HYDRO-3D, as tools for assessing and predicting best hydraulic performance of ponds. The physical model of the open ponds was scaled to provide a similar nominal retention time (NRT) of 52 hours. Under natural conditions, with a variable prevailing westerly wind opposite to the inlet, a rhodamine tracer study on the full-scale prototype pond produced a mean hydraulic retention time (MHRT) of 18.5 hours (HE = 35.5%). Simulations of these wind conditions, but with constant wind speed and direction in both the physical model and HYDRO-3D, produced a higher MHRT of 21 hours in both models and an HE of 40.4%. In the absence of wind tracer studies in the open pond physical model revealed incomplete mixing with peak concentrations leaving the model in several hours, but an increase in MHRT to 24.5-28 hours (HE = 50.2-57.1%). Although wind blowing opposite to the inlet flow increases dispersion (mixing), it reduced hydraulic performance by 18-25%. Much higher HE values were achieved by baffles (67-74%) and three channel configurations (69-92%), compared with the original open pond configuration. Good agreement was achieved between the two models where key environmental and flow parameters can be controlled and set, but it is difficult to accurately simulate full-scale works conditions due to the unpredictability of natural hourly and daily fluctuation in these parameters.
Villager is an agent-based modeling framework: it prescribes a convention and interface for modelers to create and run agent-based models (ABM). The framework is aimed at researchers in the social sciences who are focused on modeling human populations. The key features of villager are:1. Scalability: villager makes extensive use of the R6 class system (Chang, 2020), enabling the power of reference semantics without the hurdles of manual memory management. This enabled an architecture design where user-supplied functions are run within the framework. The reference semantics also enable cheaper memory operations by allowing for the mutation of agents in-place rather than costly copy semantics. 2. Extensibility: villager exposes a number of classes that can be extended by domain scientists to provide flexibility in experiment design. The extended classes can be "plugged" into the villager framework and run seamlessly.Together, these two features allow researchers to design ABMs with flexible requirements-both functionally and computationally.
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