Evaluation and Transport of the Crystallization Heat in an Iterative Self-consistent Multi-scale Simulation of Semi-crystalline Thermoplastics

Author(s):  
Christian Hopmann ◽  
Jonathan Alms ◽  
Gottfried Laschet
2021 ◽  
Author(s):  
Jinghuan Li ◽  
Xuzhi Zhou ◽  
Fan Yang ◽  
Anton V. Artemyev ◽  
Qiugang Zong

<p>Magnetic cavities are sudden depressions of magnetic field strength widely observed in the space plasma environments, which are often accompanied by plasma density and pressure enhancement. To describe these cavities, a self-consistent kinetic model has been proposed as an equilibrium solution to the Vlasov-Maxwell equations. However, observations from the Magnetospheric Multi-Scale (MMS) constellation have shown the existence of helical magnetic cavities characterized by the presence of azimuthal magnetic field, which could not be reconstructed by the aforementioned model. Here, we take into account another invariant of motion, the canonical axial momentum, to construct the particle distributions and accordingly modify the equilibrium model. The reconstructed magnetic cavity shows excellent agreement with the MMS1 observations not only in the electromagnetic field and plasma moment profiles but also in electron pitch-angle distributions. With the same set of parameters, the model also predicts signatures of the neighboring MMS3 spacecraft, matching its observations satisfactorily.</p>


2005 ◽  
Vol 276 (1-2) ◽  
pp. 133-147 ◽  
Author(s):  
Arun Pandy ◽  
Andrew Yeckel ◽  
Michael Reed ◽  
Csaba Szeles ◽  
Marc Hainke ◽  
...  

Author(s):  
Lena Noack ◽  
Nicola Tosi

Modelling of geodynamic processes like mantle or core convection has strongly improved over the last two decades thanks to the steady development of numerical codes that tend to incorporate a more and more realistic physics. High-performance parallel computations allow the simulation of complex problems, such as the self-consistent generation of tectonic plates or the formation of planetary magnetic fields. However, the need to perform broad explorations of the parameter space and the large computational demands imposed by the non-linear, multi-scale nature of convection, requires several simplifications, in the domain geometry as well as in the physical complexity of the problem. In this chapter, the authors give an overview of the state-of-the-art convection simulations in planetary mantles, the different models and geometries used, and various methods to simplify the computations.


2013 ◽  
Vol 1582 ◽  
Author(s):  
Tingting Qi ◽  
Evan J. Reed

ABSTRACTA methodology is described for atomistic simulations of shock-compressed materials that incorporates quantum nuclear effects on the fly. We introduce a modification of the multi-scale shock technique (MSST) that couples to a quantum thermal bath described by a colored noise Langevin thermostat. The new approach, which we call QB-MSST, is of comparable computational cost to MSST and self-consistently incorporates quantum heat capacities and Bose-Einstein harmonic vibrational distributions. As a first test, we study shock-compressed methane using the ReaxFF potential. The Hugoniot curves predicted from the new approach are found comparable with existing experimental data. We find that the self-consistent nature of the method results in the onset of chemistry at 40% lower pressure on the shock Hugoniot than observed with classical molecular dynamics. The temperature change associated with quantum heat capacity is determined to be the primary factor in this shift.


2018 ◽  
Vol 11 (1) ◽  
pp. 213-234 ◽  
Author(s):  
Adam S. Candy ◽  
Julie D. Pietrzak

Abstract. The approaches taken to describe and develop spatial discretisations of the domains required for geophysical simulation models are commonly ad hoc, model- or application-specific, and under-documented. This is particularly acute for simulation models that are flexible in their use of multi-scale, anisotropic, fully unstructured meshes where a relatively large number of heterogeneous parameters are required to constrain their full description. As a consequence, it can be difficult to reproduce simulations, to ensure a provenance in model data handling and initialisation, and a challenge to conduct model intercomparisons rigorously. This paper takes a novel approach to spatial discretisation, considering it much like a numerical simulation model problem of its own. It introduces a generalised, extensible, self-documenting approach to carefully describe, and necessarily fully, the constraints over the heterogeneous parameter space that determine how a domain is spatially discretised. This additionally provides a method to accurately record these constraints, using high-level natural language based abstractions that enable full accounts of provenance, sharing, and distribution. Together with this description, a generalised consistent approach to unstructured mesh generation for geophysical models is developed that is automated, robust and repeatable, quick-to-draft, rigorously verified, and consistent with the source data throughout. This interprets the description above to execute a self-consistent spatial discretisation process, which is automatically validated to expected discrete characteristics and metrics. Library code, verification tests, and examples available in the repository at https://github.com/shingleproject/Shingle. Further details of the project presented at http://shingleproject.org.


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