The conservation equations for chemical reactors

An improved analytical model for the description of the anode contraction zone of a high intensity arc takes radiation effects into account. The conservation equations for the anode contraction zone and the adjacent undisturbed arc column are solved numerically with a relaxation method. Results for atmospheric pressure argon arcs at three different currents demonstrate that radiation losses reduce temperature peaks substantially and, at the same time, provide a smooth matching of arc column and contraction zone solutions. Although the model seems to be adequate for a large portion of the anode contraction zone, the results indicate that refinements of the model are necessary for the region close to the anode, in particular, deviations from LTE have to be taken into account.

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Hidden Attractors in Discrete Dynamical Systems

Entropy ◽

10.3390/e23050616 ◽

2021 ◽

Vol 23 (5) ◽

pp. 616

Author(s):

Marek Berezowski ◽

Marcin Lawnik

Keyword(s):

Dynamical Systems ◽

Chaos Theory ◽

Scientific Literature ◽

Discrete Systems ◽

Discrete Dynamical Systems ◽

Continuous Systems ◽

Hidden Attractors ◽

Negative Effects ◽

Chemical Reactors ◽

Points Of View

Research using chaos theory allows for a better understanding of many phenomena modeled by means of dynamical systems. The appearance of chaos in a given process can lead to very negative effects, e.g., in the construction of bridges or in systems based on chemical reactors. This problem is important, especially when in a given dynamic process there are so-called hidden attractors. In the scientific literature, we can find many works that deal with this issue from both the theoretical and practical points of view. The vast majority of these works concern multidimensional continuous systems. Our work shows these attractors in discrete systems. They can occur in Newton’s recursion and in numerical integration.

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MFIX-Exa: A path toward exascale CFD-DEM simulations

The International Journal of High Performance Computing Applications ◽

10.1177/10943420211009293 ◽

2021 ◽

pp. 109434202110092

Author(s):

Jordan Musser ◽

Ann S Almgren ◽

William D Fullmer ◽

Oscar Antepara ◽

John B Bell ◽

...

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Element Model ◽

Discrete Element Model ◽

Software Framework ◽

Chemical Reactors ◽

Software Infrastructure ◽

Fundamental Physics ◽

Dem Simulations ◽

Algorithmic Approaches

MFIX-Exa is a computational fluid dynamics–discrete element model (CFD-DEM) code designed to run efficiently on current and next-generation supercomputing architectures. MFIX-Exa combines the CFD-DEM expertise embodied in the MFIX code—which was developed at NETL and is used widely in academia and industry—with the modern software framework, AMReX, developed at LBNL. The fundamental physics models follow those of the original MFIX, but the combination of new algorithmic approaches and a new software infrastructure will enable MFIX-Exa to leverage future exascale machines to optimize the modeling and design of multiphase chemical reactors.

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