Optimization Techniques for Entropy-Based Moment Closures in Linear Transport
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Abstract
Kinetic equations are used to model many physical phenomena, including gas
dynamics, semiconductors, radiative transport, and more. However, high
dimensionality of the domain of definition of the system makes simulation
difficult. The entropy-based moment closure model of the kinetic equation
reduces the dimension of the domain and has attractive theoretical and practical
properties, but most implementations have avoided numerically solving the
defining optimization problem. We use the linear one-dimensional slab-geometry
model to expose the main challenges in the use of numerical optimization then
propose an isotropic regularization and describe the benefits of using fixed
quadrature. A numerical technique using adaptive polynomial bases
in the optimization algorithm is also tested. We develop manufactured
solutions to test our algorithm and also present its performance on two standard
test problems.