Quantifying Sub-gridding Errors in Standard and Hybrid Higher Order 2D FDTD Simulations

2021 ◽  
Vol 35 (11) ◽  
pp. 1428-1429
Author(s):  
Madison Le ◽  
Mohammed Hadi ◽  
Atef Elsherbeni
Keyword(s):  
Finite Difference ◽  
Time Domain ◽  
Finite Difference Time Domain ◽  
Contrast Ratio ◽  
Higher Order ◽  
Fdtd Simulation ◽  
Fdtd Simulations ◽  
2D Fdtd ◽  
Difference Time

Sub-gridding errors for a 2D Finite-Difference Time-Domain (FDTD) simulation are compared for both the standard FDTD and Hybrid higher order FDTD cases. Subgridding contrast ratios of 1:3, 1:9, 1:15, and 1:27 are considered and analyzed. A correlation is seen between the increase of contrast ratio with the increase of sub-gridding errors for both standard and hybrid cases. However, a trend of errors reduction when using hybrid formulations over standard formulations is apparent for each contrast ratio.

Finite-Difference Time-Domain Simulation of Microwave Sintering in A Variable-Frequency Multimode Cavity

1996 ◽  
Vol 430 ◽  
Author(s):  
Mikel J White ◽  
Steven F. Dillon ◽  
Magdy F. Iskander ◽  
Hal D. Kimrey
Keyword(s):  
Finite Difference ◽  
Time Domain ◽  
Finite Difference Time Domain ◽  
Microwave Sintering ◽  
Single Frequency ◽  
Frequency Variation ◽  
Variable Frequency ◽  
Frequency Range ◽  
Fdtd Simulations ◽  
Difference Time

AbstractThere have been recent indications that variable-frequency microwave sintering of ceramics provides several advantages over single-frequency sintering, including more uniform heating, particularly for larger samples. The Finite-Difference Time-Domain (FDTD) code at the University of Utah was modified and used to simulate microwave sintering using variable frequencies and was coupled with a heat-transfer code to provide a dynamic simulation of this new microwave sintering process. This paper summarizes results from the FDTD simulations of sintering in a variable-frequency cavity. FDTD simulations were run in 100-MHz steps to account for the frequency variation in the electromagnetic fields in the multimode cavity. It is shown that a variable-frequency system does improve the heating uniformity when the proper frequency range is chosen. Specifically, for a single ceramic sample (4 × 4 × 6 cm3), and for a variable-frequency range from f = 2.5 GHz to f = 3.2 GHz, the temperature distribution pattern was much more uniform than the heating pattern achieved when using a single-frequency sintering system at f = 2.45 GHz.

scholarly journals A higher order perfectly matched layer formulation for finite-difference time-domain seismic wave modeling

Geophysics ◽  
2015 ◽  
Vol 80 (1) ◽  
pp. T1-T16 ◽  
Author(s):  
David P. Connolly ◽  
Antonios Giannopoulos ◽  
Michael C. Forde
Keyword(s):  
Finite Difference ◽  
Time Domain ◽  
Finite Difference Time Domain ◽  
Degrees Of Freedom ◽  
Higher Order ◽  
Staggered Grid ◽  
First Order ◽  
Enhanced Absorption ◽  
Absorption Performance ◽  
Difference Time

We have developed a higher order perfectly matched layer (PML) formulation to improve the absorption performance for finite-difference time-domain seismic modeling. First, we outlined a new unsplit “correction” approach, which allowed for traditional, first-order PMLs to be added directly to existing codes in a straightforward manner. Then, using this framework, we constructed a PML formulation that can be used to construct higher order PMLs of arbitrary order. The greater number of degrees of freedom associated with the higher order PML allow for enhanced flexibility of the PML stretching functions, thus potentially facilitating enhanced absorption performance. We found that the new approach can offer increased elastodynamic absorption, particularly for evanescent waves. We also discovered that the extra degrees of freedom associated with the higher order PML required careful optimization if enhanced absorption was to be achieved. Furthermore, these extra degrees of freedom increased the computational requirements in comparison with first-order schemes. We reached our formulations using one compact equation thus increasing the ease of implementation. Additionally, the formulations are based on a recursive integration approach that reduce PML memory requirements, and do not require special consideration for corner regions. We tested the new formulations to determine their ability to absorb body waves and surface waves. We also tested standard staggered grid stencils and rotated staggered grid stencils.

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