439 research outputs found
Physics-informed Neural Network for Acoustic Resonance Analysis
This study proposes the physics-informed neural network (PINN) framework to
solve the wave equation for acoustic resonance analysis. ResoNet, the
analytical model proposed in this study, minimizes the loss function for
periodic solutions, in addition to conventional PINN loss functions, thereby
effectively using the function approximation capability of neural networks,
while performing resonance analysis. Additionally, it can be easily applied to
inverse problems. Herein, the resonance in a one-dimensional acoustic tube was
analyzed. The effectiveness of the proposed method was validated through the
forward and inverse analyses of the wave equation with energy-loss terms. In
the forward analysis, the applicability of PINN to the resonance problem was
evaluated by comparison with the finite-difference method. The inverse
analysis, which included the identification of the energy loss term in the wave
equation and design optimization of the acoustic tube, was performed with good
accuracy.Comment: 11 pages, 14 figures. The following article has been submitted to the
Journal of the Acoustical Society of America. After it is published, it will
be found at https://pubs.aip.org/asa/jasa . v2: Corrected a typo in Eq. (22
Anaerosphaera aminiphila gen. nov., sp. nov., a novel, glutamate-degrading, Gram-positive anaerobic coccus isolated from a methanogenic reactor of cattle waste
Propioniciclava tarda gen. nov., sp. nov., isolated from a methanogenic reactor treating waste from cattle farms.
Bacteroides paurosaccharolyticus sp. nov., isolated from a methanogenic reactor treating waste from cattle farms.
Clinical course of reverse redistribution on Thallium-210 myocardial SPECT in patients with myocardial infarction
Flow transition criteria of a liquid jet into a liquid pool
To better understand the fundamental interactions between melt jet and coolant during a core-disruptive accident at a sodium-cooled fast reactor, the jet breakup and droplet formation in immiscible liquid-liquid systems were studied experimentally. Experiments using two different pairs of test fluids were carried out at isothermal conditions. The observed jet breakup behavior was classified into characteristic regimes based on the classical Ohnesorge classification in liquid-gas systems. The variation in breakup length obtained in the present liquid-liquid system was similar to that in a liquid-gas system. The droplet size distribution in each breakup regime was analyzed using image processing and droplet formation via pinch-off, satellite formation, and entrainment was observed. The measured droplet size was compared with those available from melt jet experiments. Based on the observation and analysis results, the breakup regimes were organized on a dimensionless operating diagram, with the derived correlations representing the criteria for regime boundaries of a liquid-liquid system. Finally, the experimental data were extrapolated to the expected conditions of a sodium-cooled fast reactor. From this, it was implied that most of the hydrodynamic conditions during an accident would be close to the atomization regime, in which entrainment is the dominant process for droplet formation
Lattice Boltzmann modeling and simulation of liquid jet breakup
A three-dimensional color-fluid lattice Boltzmann model for immiscible two-phase flows is developed in the framework of a three-dimensional 27-velocity (D3Q27) lattice. The collision operator comprises the D3Q27 versions of three suboperators: a multiple-relaxation-time (MRT) collision operator, a generalized Liu–Valocchi–Kang perturbation operator, and a Latva-Kokko–Rothman recoloring operator. A D3Q27 version of an enhanced equilibrium distribution function is also incorporated into this model to improve the Galilean invariance. Three types of numerical tests, namely, a static droplet, an oscillating droplet, and the Rayleigh–Taylor instability, show a good agreement with analytical solutions and numerical simulations. Following these numerical tests, this model is applied to liquid-jet-breakup simulations. The simulation conditions are matched to the conditions of the previous experiments. In this case, numerical stability is maintained throughout the simulation, although the kinematic viscosity for the continuous phase is set as low as 1.8×10−4, in which case the corresponding Reynolds number is 3.4×103; the developed lattice Boltzmann model based on the D3Q27 lattice enables us to perform the simulation with parameters directly matched to the experiments. The jet\u27s liquid column transitions from an asymmetrical to an axisymmetrical shape, and entrainment occurs from the side of the jet. The measured time history of the jet\u27s leading-edge position shows a good agreement with the experiments. Finally, the reproducibility of the regime map for liquid-liquid systems is assessed. The present lattice Boltzmann simulations well reproduce the characteristics of predicted regimes, including varicose breakup, sinuous breakup, and atomization
- …