scholarly journals A high order splitting method for time-dependent domains

2008 ◽  
Vol 197 (51-52) ◽  
pp. 4763-4773 ◽  
Author(s):  
Tormod Bjøntegaard ◽  
Einar M. Rønquist
Keyword(s):  
Splitting Method ◽  
High Order ◽  
Time Dependent

scholarly journals Integrating Semilinear Wave Problems with Time-Dependent Boundary Values Using Arbitrarily High-Order Splitting Methods

Mathematics ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 1113
Author(s):  
Isaías Alonso-Mallo ◽  
Ana M. Portillo
Keyword(s):  
Numerical Experiments ◽  
Splitting Method ◽  
Method Of Lines ◽  
Time Integration ◽  
Initial Boundary ◽  
Initial Boundary Value Problem ◽  
High Order ◽  
Time Dependent ◽  
Boundary Values ◽  
Lipschitz Continuous

The initial boundary-value problem associated to a semilinear wave equation with time-dependent boundary values was approximated by using the method of lines. Time integration is achieved by means of an explicit time method obtained from an arbitrarily high-order splitting scheme. We propose a technique to incorporate the boundary values that is more accurate than the one obtained in the standard way, which is clearly seen in the numerical experiments. We prove the consistency and convergence, with the same order of the splitting method, of the full discretization carried out with this technique. Although we performed mathematical analysis under the hypothesis that the source term was Lipschitz-continuous, numerical experiments show that this technique works in more general cases.

scholarly journals High Order Semi-implicit Multistep Methods for Time-Dependent Partial Differential Equations

2021 ◽  
Author(s):  
Giacomo Albi ◽  
Lorenzo Pareschi
Keyword(s):  
Multistep Methods ◽  
General Setting ◽  
Reaction Diffusion ◽  
Strong Stability ◽  
High Order ◽  
Iterative Solvers ◽  
Time Dependent ◽  
Linear Multistep Methods ◽  
Advection Diffusion Equation ◽  
Separation Of Scales

AbstractWe consider the construction of semi-implicit linear multistep methods that can be applied to time-dependent PDEs where the separation of scales in additive form, typically used in implicit-explicit (IMEX) methods, is not possible. As shown in Boscarino et al. (J. Sci. Comput. 68: 975–1001, 2016) for Runge-Kutta methods, these semi-implicit techniques give a great flexibility, and allow, in many cases, the construction of simple linearly implicit schemes with no need of iterative solvers. In this work, we develop a general setting for the construction of high order semi-implicit linear multistep methods and analyze their stability properties for a prototype linear advection-diffusion equation and in the setting of strong stability preserving (SSP) methods. Our findings are demonstrated on several examples, including nonlinear reaction-diffusion and convection-diffusion problems.

AUSM-Based High-Order Solution for Euler Equations

2012 ◽  
Vol 12 (4) ◽  
pp. 1096-1120 ◽  
Author(s):  
Angelo L. Scandaliato ◽  
Meng-Sing Liou
Keyword(s):  
Euler Equations ◽  
Splitting Method ◽  
High Order ◽  
Riemann Solvers ◽  
Carbuncle Phenomenon ◽  
Solution Accuracy ◽  
Matrix Vector ◽  
Approximate Riemann Solvers ◽  
Monotonicity Preserving ◽  
High Order Interpolation

AbstractIn this paper we demonstrate the accuracy and robustness of combining the advection upwind splitting method (AUSM), specifically AUSM+-UP, with high-order upwind-biased interpolation procedures, the weighted essentially non-oscillatory (WENO-JS) scheme and its variations, and the monotonicity preserving (MP) scheme, for solving the Euler equations. MP is found to be more effective than the three WENO variations studied. AUSM+-UP is also shown to be free of the so-called “carbuncle” phenomenon with the high-order interpolation. The characteristic variables are preferred for interpolation after comparing the results using primitive and conservative variables, even though they require additional matrix-vector operations. Results using the Roe flux with an entropy fix and the Lax-Friedrichs approximate Riemann solvers are also included for comparison. In addition, four reflective boundary condition implementations are compared for their effects on residual convergence and solution accuracy. Finally, a measure for quantifying the efficiency of obtaining high order solutions is proposed; the measure reveals that a maximum return is reached after which no improvement in accuracy is possible for a given grid size.

A Numerical Study of Quantum Decoherence

2012 ◽  
Vol 12 (1) ◽  
pp. 85-108 ◽  
Author(s):  
Riccardo Adami ◽  
Claudia Negulescu
Keyword(s):  
Density Matrix ◽  
Particle Density ◽  
Numerical Study ◽  
Heavy Particle ◽  
Splitting Method ◽  
Time Dependent ◽  
Quantum Decoherence ◽  
Approximation Formula ◽  
Time Splitting ◽  
Decoherence Effect

AbstractThe present paper provides a numerical investigation of the decoherence effect induced on a quantum heavy particle by the scattering with a light one. The time dependent two-particle Schrödinger equation is solved by means of a time-splitting method. The damping undergone by the non-diagonal terms of the heavy particle density matrix is estimated numerically as well as the error in the Joos-Zeh approximation formula.

High-order harmonic generation with a single-color mid-infrared laser field by frequency-chirping

2019 ◽  
Vol 33 (13) ◽  
pp. 1950122 ◽  
Author(s):  
Yunhui Wang ◽  
Dandan Song ◽  
Qiang Zuo ◽  
Hong Wu ◽  
Zhihong Yang
Keyword(s):  
Harmonic Generation ◽  
Laser Field ◽  
Infrared Laser ◽  
Pulse Generation ◽  
High Order ◽  
Time Dependent ◽  
Mid Infrared ◽  
High Order Harmonic ◽  
Isolated Attosecond Pulse ◽  
Frequency Chirping

By numerically solving the time-dependent Schrödinger equation for helium atoms in a single mid-infrared laser field, we explore the frequency-chirping effect of laser field on high-order harmonic and isolated attosecond pulse generation. One or two ultrabroad supercontinuum harmonic plateaus can be controlled through modulating the laser field frequency by a small time-dependent signal. Under the best chirping condition, an ultrashort 2.2 as pulse can be obtained by Fourier transformation with the bandwidth of 782 eV. Furthermore, we explain the harmonic generation physical mechanisms by classical ionizing and returning energy maps and time–frequency analyzes.

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