Modelling Practices and Practices of Modelling

Modelling represents a core method of investigation in the sciences. Relying on a number of case studies, I want to explore the main concepts that denote the practice of modeling in pure and applied sciences. I argue that these concepts could be seen as metaphors to reflect upon when exploring how the practices of modeling are characterised across different disciplines

Numerical prediction of sloshing loads in flexible tanks

The scope of the presentation is to review our ongoing research on the numerical modeling of sloshing in deformable tanks

Time domain analysis of ship motion and wave loads by boundary integral equations

In this presentation, we like to discuss some aspects of a more general computational algorithm for the prediction of ship motion and loads induced by the interaction with wave systems. In particular, unlikely the more conventional models in frequency domain, we attack the problem by a time domain formulation. The purpose is twofold. First, within the framework of a linear analysis, the ship response function to a general wave excitation can be numerically determined by a transient test (i.e. the interaction with a wave pulse compact in time). In this way, a substantial saving of computational time with respect to the existing algorithm is achieved. Second, a time domain modeling is intrinsically prone to deal with the fully nonlinear problem or, at least, to recover some nonlinear effects

Confronto di solutori FEM e solutori BEM per lo sloshing in contenitori

Ė stato studiato il fenomeno di sloshing attraverso due diversi algoritmi numerici: il primo consiste in una discretizzazione con elementi finiti dell’equazione di Navier Stokes in formulazione Arbitrary Lagrangian Eulerian, è indicato nel seguito come FEM ed è descritto in [3]; il secondo è basato sulla discretizzazione delle equazioni agli integrali di contorno e delle equazioni di evoluzione della superficie libera ed è indicato come BEM e descritto in [2]. Per verificare la validità dei due codici sono stati confrontati i loro risultati con quelli presenti in letteratura, sia derivanti da altri codici numerici, sia ottenuti come risultati sperimentali. Il confronto è stato effettuato per un’ampia gamma di situazioni, in modo da studiare il comportamento dei due codici al variare delle caratteristiche della sollecitazione e delle dimensioni del dominio

Fluid-solid interaction modeling for sloshing flows in flexible tanks

The scope of the presentation is to review our ongoing research on the numerical modeling of sloshing in deformable tanks

A thermal fluid-dynamic transient analysis of the EADF down-comer channel

In this work a numerical simulation of the downcomer channel of the Energy Amplifier Demonstration Facility (EADF) [1, 2] is presented. The simulation is fully three-dimensional (3D) and is focused on a transient analysis. All relevant heat transfer phenomena are taken into account. Starting from the nominal power configuration, we have simulated the response of the system to a power shutdown of the core for a period of 60 s. The core shutdown is simulated imposing a linear variation of the inlet flow temperature from 400°C to 305°C in 10 s. The simulation shows the evolution of the thermal stratification outside the IHX and the evolution of the IHX operation

A beam window target design with independent cooling for the EADF

This report summarizes the study and the design of the window type target for the Energy Amplifier Demonstration Facility (EADF) [1]. The behaviour of the system in different condition has been analysed though extensive CFD simulations performed with the Star-CD commercial code [2]. The target represents one of the main technological problems related not only to the design of the EADF, but to all High Power Spallation Sources (HPSS) currently under study or in construction world-wide [4],[5]. Different configurations of the spallation EADF target are possible. Advantages and disadvantages of the different options are discussed elsewhere [6] and they are studied and analysed separately. The target device studied in this report is a window type target, cooled by diathermic oil in an independent loop. This target configuration is completely independent from the core operating conditions and gives advantages in terms of flexibility in the operation. The result of this report is a set of design data and constraints to take into account while engineering the spallation target

A heat exchanger design for the separated window target of the EADF

The spallation target of the Energy Amplifier Demonstration Facility (EADF) [1] is cooled by a liquid lead-bismuth eutectic (LBE), while the secondary coolant is a diathermic oil. The reasons for these choices have been extensively discussed in [2] and [3]. Here we present the design and the optimisation of a heat exchanger using these fluids, whose additional requirements are the need of fitting into the top of the annular downcomer section of the target and the minimisation of the pressure losses on the LBE side, allowing the use of natural convection for the circulation of the primary fluid. Heat exchanger working temperatures are between 250 and 180°C in the LBE side, and between 150 and 190°C in the oil side (cold fluid), while the power to be removed is up to 3 MW. We selected a bayonet-type heat exchanger, as suggested in [4] for the primary loop of the EADF vessel, which seems to be the most appropriate choice to satisfy all the requirements

A thermal fluid-dynamic steady state analysis of the EADF downcomer channel

In this work a numerical simulation of the Energy Amplifier Demonstration Facility (EADF) [1, 2] downcomer channel is presented. The simulation is fully three-dimensional (3D) and is focused on a Steady-State Analysis. All relevant heat transfer phenomena are taken into account. The Intermediate Heat eXchangers (IHX) of the EADF reference configuration are immersed in the lead-bismuth eutectic of the downcomer and no physical barrier separates the hot and cold collectors. As expected, the simulation shows a thermal stratification outside the IHX, whose characteristics mainly depend on the IHX pressure loss. A parametric study of the effects of the IHX pressure loss coeficient on the thermal stratification pattern is presented