The Challenges of In Situ Analysis for Multiple Simulations

International audienceIn situ analysis and visualization have mainly been applied to the output of a single large-scale simulation. However, topics involving the execution of multiple simulations in supercomputers have only received minimal attention so far. Some important examples are uncertainty quantification, data assimilation, and complex optimization. In this position article, beyond highlighting the strengths and limitations of the tools that we have developed over the past few years, we share lessons learned from using them on large-scale platforms and from interacting with end users. We then discuss the forthcoming challenges, which future in situ analysis and vi-sualization frameworks will face when dealing with the exascale execution of multiple simulations

Captura de proveniência assíncrona em simulações computacionais

Large-scale computational simulations are computational experiments increasingly more processing intensive. Users and developers of this type of simulation generally analyze data during simulation execution. This is not a trivial task since largescale simulations are often performed in high-performance processing environments and can produce a large volume of data. Existing solutions, as DfAnalyzer, use provenance data to assist analysis with success. However, these systems use synchronous approaches to gather data that makes difficult to set up it and, mainly, interferes in the performance of the computational simulation. This dissertation proposes an approach to asynchronously collect provenance data making it available for analysis during the execution of the simulation with the least possible delay. In order to evaluate the proposed strategies, a tool, Asynchronous Dataflow Analyzer. This implementation extends DfAnalyzer to use the proposed asynchronous approach and to simplify the configuration process by making the prospective provenance definition process more flexible. The experimental results, with a soils sedimentation simulation, show that the tool is able to meet the needs of users of large-scale computational simulations with lower overloads than similar tools.Simulações computacionais em larga escala são experimentos computacionais cada vez com mais processamento de dados. Usuários e desenvolvedores deste tipo de simulação geralmente realizam análises sobre dados científicos durante a execução da simulação. Esta não é uma tarefa trivial, já que as simulações em larga escala costumam ser executadas em ambientes de processamento de alto desempenho e produzir grande volume de dados. Soluções existentes, como o DfAnalyzer, fazem uso de dados de proveniência para auxiliar esta análise com muito sucesso. No entanto, esses sistemas possuem abordagens síncronas de coleta de dados, o que dificulta a sua instalação e, principalmente, interfere no desempenho da simulação computacional. Esta dissertação propõe uma abordagem assíncrona de coleta de dados de proveniência com o objetivo de disponibilizar dados científicos para consulta durante a execução da simulação sem muito impacto no seu tempo de execução. Para validar as estratégias propostas, foi desenvolvida a ferramenta Asynchronous Dataflow Analyzer. A implementação realizada estende o DfAnalyzer para adotar o assincronismo proposto e simplifica a configuração do sistema por meio da flexibilização da gerência da proveniência prospectiva. Os resultados experimentais, com uma simulação de processos de sedimentação de solos, mostram que a ferramenta é capaz de atender as necessidades de análises de dados dos usuários de simulações computacionais com sobrecargas inferiores a ferramentas existentes

Design of an Intensified Reactor for the Synthetic Natural Gas Production through Methanation in the Carbon Capture and Utilization Context

112 páginasThe idea of a sustainable future has led to the exclusion of fossil fuels from development policies and the inclusion of low-carbon alternatives instead. The strategy must be holistic, as proposed by the carbon capture and utilization technologies alongside renewable energies. An example is converting CO2 into value-added products, such as CH4 or Synthetic Natural Gas (SNG), using surplus power of renewable alternatives, in a low-carbon footprint process. The chemical route for the synthesis of SNG from CO2 and H2 is a catalytic reaction known as CO2 methanation or Sabatier reaction. The methanation is an example of CO2 capture and utilization technologies' industrial application within the so-called Power-to-Methane (PtM) context. In this scenario, fixed bed reactors have been the reaction technology employed by default. However, their deficiency in handling the heat released from the highly exothermic Sabatier reaction or responding to the process' intermittency appropriately has been demonstrated. These drawbacks have aroused scientific interest in developing reactors better adapted to the PtM context demands. One approach is by intensifying the methanation process to increase the mass- and energy-transfer and improve its transient response. In this project, the phenomenological hot spots formation in fixed bed reactors used for the methanation industrial process was investigated through a parametric sensitivity analysis, simulating the reactor start-up. On the other hand, it was proposed a CFD simulation-aided conceptual design of a wall-coated reactor for the SNG production using an intensification strategy. The design was based on a reactor formed by single-pass and heat-exchanger stacked-plates. The reacting channel dimensions were defined, including the catalytic layer thickness, fulfilling a minimum quality threshold given by the CO2 conversion (≥ 95%). The proposed design was also intended to maximize the volume of processed gas while meeting the quality requirement, resulting in a throughput per reaction channel of ~12 ml/min. Likewise, the plates manifold geometry and dimensions that best promoted a flow rate uniform distribution were established as a function of the number of reacting channels. Finally, a preliminary dynamic analysis of the operation start-up and shutdown was performed, establishing that the designed reactor does not present a hysteresis behaviour, an ideal condition for intermittent environments.La idea de un futuro sostenible ha conllevado a suprimir el uso de combustibles de origen fósil de los planes de desarrollo y por el contrario incluir alternativas con baja huella de carbono. La estrategia debe ser holística, como lo proponen las tecnologías de captura y utilización de CO2 junto con las energías renovables. Un ejemplo es la conversión del CO2 en productos con valor agregado, como el CH4 o Gas Natural Sintético (GNS), utilizando la energía sobrante de las alternativas renovables, en un proceso con baja huella de carbono. La ruta química para síntesis de GNS a partir de CO2 e H2 es una reacción catalítica que se conoce como metanación de CO2 o reacción de Sabatier. La metanación es un ejemplo de aplicación industrial de las tecnologías de captura y utilización de CO2 en lo que también se conoce como el contexto Power-to-Methane (PtM). En ese ámbito, los reactores de lecho fijo han sido la tecnología de reacción utilizada por defecto. Sin embargo, se ha demostrado su incapacidad para manejar el calor liberado producto de la reacción de Sabatier (altamente exotérmica), o de responder apropiadamente a la intermitencia del proceso. Estas dificultades han despertado el interés científico por desarrollar reactores que se adapten mejor a las exigencias del contexto PtM. Una propuesta yace en intensificar el proceso de metanación, incrementando la transferencia de masa y energía además de mejorar su respuesta transitoria. En este proyecto se estudió, por un lado, la formación fenomenológica de puntos calientes en reactores de lecho fijo utilizados industrialmente para el proceso de metanación a través de un análisis de sensibilidad paramétrico, simulando el arranque del reactor. Por el otro lado, se propuso un diseño conceptual asistido por simulación CFD de un reactor de pared recubierta para la producción de GNS a través de una estrategia de intensificación. El diseño partió de un reactor formado por platos apilados de intercambio de calor de un solo paso. Se definieron las dimensiones del canal de reacción, incluyendo el grosor de la capa catalítica, que cumplían con el umbral mínimo de calidad dado por la conversión de CO2 (≥ 95%). El diseño propuesto también tuvo por objeto maximizar el volumen de gas procesado, cumpliendo a la vez con el requisito de calidad, lo que resultó en un rendimiento por canal de reacción de ~12 ml/min. Así mismo se estableció la geometría y dimensiones del colector del plato que mejor favorecían una distribución uniforme de la velocidad del flujo en función del número de canales de reacción. Por último, se realizó un análisis dinámico preliminar del arranque y apagado de la operación, estableciendo que el reactor diseñado no presenta un comportamiento de histéresis, ideal para un entorno con alta intermitencia.Maestría en Diseño y Gestión de ProcesosMagíster en Diseño y Gestión de Proceso

In situ visualization and data analysis for turbidity currents simulation

International audienceTurbidity currents are underflows responsible for sediment deposits that generate geological formations of interest for the oil and gas industry. libMesh-sedimentation is an application built upon the libMesh library to simulate turbidity currents. In this work, we present the integration of libMesh-sedimentation with in situ visualization and in transit data analysis tools. DfAnalyzer is a solution based on provenance data to extract and relate strategic simulation data in transit from multiple data for online queries. We integrate libMesh-sedimentation and ParaView Catalyst to perform in situ data analysis and visualization. We present a parallel performance analysis for two turbidity currents simulations showing that the overhead for both in situ visualization and in transit data analysis is negligible. We show that our tools enable monitoring the sediments appearance at runtime and steer the simulation based on the solver convergence and visual information on the sediment deposits, thus enhancing the analytical power of turbidity currents simulations