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Showing 1 to 14 of 14 for “"IMEX"”.
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Relativistic neutron stars in general relativity and fourth order gravity
… case, we deal with stiffness by employing an IMEX Runge-Kutta scheme as opposed to the more computationally intensive fully implicit schemes or other adaptive Runge Kutta methods that may be impractical for partial differential equations. The first problem is focused on the mass-radius …
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Efficient Time Stepping Methods and Sensitivity Analysis for Large Scale Systems of Differential Equations
… This work develops novel implicit-explicit (IMEX) general linear time integration methods for multiphysics and multiscale simulations typically involving both stiff and non-stiff components. In an IMEX approach, one uses an implicit scheme for the stiff components and an explicit scheme for …
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Efficient Multiphysics Coupling for Fast Burst Reactors in Slab Geometry
… neutronics and linear. An implicit-explicit (IMEX) algorithm was used to follow the dynamical time-scale of the problem. However, as noted by him and his co-authors, the diffusion model does not adequately represent the neutronics of the system due to its small. Our objective is to extend the …
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Implementation of an implicit-explicit scheme for hybridizable discontinuous Galerkin
… either on their own. Thus, an implicit-explicit (IMEX) scheme that splits the computational domain into implicit and explicit regions based on the domain geometry is considered in this thesis. This allows for stability throughout the domain and exploits the advantages each scheme has to offer. A …
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Implicit-explicit methods for time-dependent PDE’s
… terms of different types, implicit-explicit (IMEX) schemes have been used, especially in conjunction with spectral methods. For convection-diffusion problems, for example, one would use an explicit scheme for the convection term and an implicit scheme for thediffusion term. Reaction-diffusion …
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Perfectly Matched Layer Absorbing Boundary Conditions for the Discrete Velocity Boltzmann-BGK Equation
… Alternatively, implicit-explicit Runge-Kutta (IMEX) schemes are used in the finite difference model and are implemented explicitly by exploiting the special structure of the Boltzmann-BGK equation. This yields a numerically stable solution by the finite difference schemes. As the lattice model …
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High order stochastic transport and Lagrangian data assimilation
… method with new high order implicitexplicit (IMEX) linear multi-step and multistage IMEX-RK time marching schemes for the coupled DO equations to ensure further stability and accuracy. We also review efficient numerical re-orthonormalization strategies during time marching. We showcase our …
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A Hybrid Spectral-Element / Finite-Element Time-Domain Method for Multiscale Electromagnetic Simulations
… we employ hybrid implicit / explicit (IMEX) time-stepping schemes, where explicit schemes are used for electrically coarse subdomains discretized by coarse spectral element meshes, and implicit schemes are used to overcome the CFL limit for electrically fine subdomains discretized by …
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Numerical Methods for All Mach Number flows for Gas Dynamics
… gas in both cases. Both approaches are based on IMEX strategy, in which some term is treated explicitly, while other terms are treated implicitly, thus avoiding the classical CFL restriction due to acoustic waves. - In Isentropic Euler Case: The core if the implicit term contains a non-linear …
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Avaliação de técnicas de acoplamento parcial entre simuladores geomecânico e de fluxo
… iterativo) entre o simulador de fluxo comercial Imex® e um simulador geomecânico. Isso é feito através do desenvolvimento de um programa de acoplamento que calcula a compressibilidade dos poros de acordo com a deformação volumétrica das rochas e atualiza a compressibilidade para a simulação de …
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Numerical Simulation of pressure Transient Analysis in Tight Formation and Field Data Categorization and Typical Well Production Data Analysis
… employing a commercial reservoir simulator, CMG IMEX, a 3D finite-difference reservoir simulation package which is widely and popularly accepted by petroleum industry. Pressure transient features are discussed and compared. As noted by many findings, it is shown that fully-filled and regional …
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Speeding up high-order algorithms in computational fluid and kinetic dynamics: based on characteristics tracing and low-rank structures
… for convection equations and implicit-explicit (IMEX) Runge-Kutta methods for convection-diffusion equations. The algorithm extends to higher dimensions via dimensional splitting. Numerical experiments demonstrate the algorithm's robustness, high-order accuracy, and ability to handle extra large …
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Adaptive Numerical Methods for Large Scale Simulations and Data Assimilation
Numerical simulation is necessary to understand natural phenomena, make assessments and predictions in various research and engineering fields, develop new technologies, etc. New algorithms are needed to take advantage of the increasing computational resources and utilize the emerging hardware and …
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Eternal Solutions and Heteroclinic Orbits of a Semilinear Parabolic Equation
This dissertation describes the space of heteroclinic orbits for a class of semilinear parabolic equations, focusing primarily on the case where the nonlinearity is a second degree polynomial with variable coefficients. Along the way, a new and elementary proof of existence and uniqueness of …