Comparing numerical accuracy and stability for different horizontal discretizations in MPAS-Ocean

2021 ◽  
pp. 101908
Author(s):  
Sara Calandrini ◽  
Darren Engwirda ◽  
Mark Petersen
Keyword(s):  
Numerical Accuracy ◽  
Accuracy And Stability

OPTIMIZED DIFFERENTIATION SCHEMES ON NON-UNIFORM GRIDS FOR COMPUTATIONAL AEROACOUSTICS

2002 ◽  
Vol 10 (02) ◽  
pp. 195-209
Author(s):  
E. J. AVITAL
Keyword(s):  
Dispersion Relation ◽  
Spatial Differentiation ◽  
Optimization Procedure ◽  
Uniform Grid ◽  
Computational Aeroacoustics ◽  
Numerical Accuracy ◽  
High Order Scheme ◽  
Uniform Grids ◽  
Order Scheme ◽  
Accuracy And Stability

Dispersion-relation-preserving (DRP) spatial differentiation schemes are investigated for staggered non-uniform finite-volume grid type. It is shown that the staggering improves the numerical accuracy and stability whether the grid is uniform or non-uniform. The effect of the non-uniformity in the grid on the optimization procedure of the schemes is discussed. The spatial differentiation schemes are tested for the aeroacoustic problems of monopole and quadrupole radiation, showing the effectiveness of the non-uniform grid and the optimized high-order scheme.

A NOVEL SCHEME FOR FORCE TERM IN THE LATTICE BGK MODEL

2006 ◽  
Vol 17 (07) ◽  
pp. 945-958 ◽  
Author(s):  
RUI DU ◽  
BAOCHANG SHI
Keyword(s):  
Numerical Simulation ◽  
Navier Stokes ◽  
Evolutionary Equation ◽  
Constant Force ◽  
Force Term ◽  
Bgk Model ◽  
Numerical Accuracy ◽  
Special Cases ◽  
Discrete Methods ◽  
Accuracy And Stability

In this paper a novel scheme of the lattice BGK (LBGK) model with a force term has been proposed. Unlike the existing models, an appropriate term was added in the evolutionary equation. Through the Chapman–Enskog (C–E) procedure the Navier–Stokes (N–S) equations with a force term can be recovered with the kinetic viscosity. Three discrete methods of the added term have been discussed in detail. It can be proved that some existing models are the special cases of the model in this paper. We have taken the numerical simulation of the generalized Poiseuille flow driven by a constant force in a channel filled with a porous medium of porosity flow in 2D with different values of the parameters and compared the three models of different discrete schemes in the aspect of the numerical accuracy and stability.

Issues of numerical accuracy and stability in inverse simulation

2008 ◽  
Vol 16 (9) ◽  
pp. 1350-1364 ◽  
Author(s):  
Linghai Lu ◽  
David J. Murray-Smith ◽  
D.G. Thomson
Keyword(s):  
Numerical Accuracy ◽  
Inverse Simulation ◽  
Accuracy And Stability

scholarly journals Shaping the equation of state to improve numerical accuracy and stability of the pseudopotential lattice Boltzmann method

2022 ◽  
Vol 105 (1) ◽  
Author(s):  
Luiz Eduardo Czelusniak ◽  
Vinícius Pessoa Mapelli ◽  
Alexander J. Wagner ◽  
Luben Cabezas-Gómez
Keyword(s):  
Equation Of State ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Numerical Accuracy ◽  
Boltzmann Method ◽  
Accuracy And Stability

Linear Visco-Resistive Computations of Magnetohydrodynamic Waves: I. The Code and Test Cases

1994 ◽  
Vol 144 ◽  
pp. 503-505
Author(s):  
R. Erdélyi ◽  
M. Goossens ◽  
S. Poedts
Keyword(s):  
Resonant Absorption ◽  
Numerical Code ◽  
Mhd Waves ◽  
Test Cases ◽  
Numerical Accuracy ◽  
Element Discretization ◽  
Flux Tubes ◽  
Magnetohydrodynamic Waves ◽  
Viscosity Coefficients ◽  
Magnetic Flux Tubes

AbstractThe stationary state of resonant absorption of linear, MHD waves in cylindrical magnetic flux tubes is studied in viscous, compressible MHD with a numerical code using finite element discretization. The full viscosity tensor with the five viscosity coefficients as given by Braginskii is included in the analysis. Our computations reproduce the absorption rates obtained by Lou in scalar viscous MHD and Goossens and Poedts in resistive MHD, which guarantee the numerical accuracy of the tensorial viscous MHD code.

Reconstruction of complex shaped crack from ECT signals based on a fast forward solver using an advanced multi-media element

2020 ◽  
Vol 64 (1-4) ◽  
pp. 621-629
Author(s):  
Yingsong Zhao ◽  
Cherdpong Jomdecha ◽  
Shejuan Xie ◽  
Zhenmao Chen ◽  
Pan Qi ◽  
...  
Keyword(s):  
Coefficient Matrix ◽  
Crack Edge ◽  
Numerical Accuracy ◽  
Gauss Point ◽  
Current Testing ◽  
Efficient Simulation ◽  
Shaped Crack ◽  
Multi Media ◽  
Profile Reconstruction ◽  
Crack Profile

In this paper, the conventional database type fast forward solver for efficient simulation of eddy current testing (ECT) signals is upgraded by using an advanced multi-media finite element (MME) at the crack edge for treating inversion of complex shaped crack. Because the analysis domain is limited at the crack region, the fast forward solver can significantly improve the numerical accuracy and efficiency once the coefficient matrices of the MME can be properly calculated. Instead of the Gauss point classification, a new scheme to calculate the coefficient matrix of the MME is proposed and implemented to upgrade the ECT fast forward solver. To verify its efficiency and the feasibility for reconstruction of complex shaped crack, several cracks were reconstructed through inverse analysis using the new MME scheme. The numerical results proved that the upgraded fast forward solver can give better accuracy for simulating ECT signals, and consequently gives better crack profile reconstruction.

scholarly journals Dirichlet absorbing boundary conditions for classical and peridynamic diffusion-type models

2020 ◽  
Vol 66 (4) ◽  
pp. 773-793 ◽  
Author(s):  
Arman Shojaei ◽  
Alexander Hermann ◽  
Pablo Seleson ◽  
Christian J. Cyron
Keyword(s):  
Boundary Conditions ◽  
Materials Science ◽  
Unbounded Domains ◽  
Diffusion Models ◽  
Absorbing Boundary Conditions ◽  
The Finite Element Method ◽  
Absorbing Boundary ◽  
Diffusion Type ◽  
2D And 3D ◽  
Accuracy And Stability

Abstract Diffusion-type problems in (nearly) unbounded domains play important roles in various fields of fluid dynamics, biology, and materials science. The aim of this paper is to construct accurate absorbing boundary conditions (ABCs) suitable for classical (local) as well as nonlocal peridynamic (PD) diffusion models. The main focus of the present study is on the PD diffusion formulation. The majority of the PD diffusion models proposed so far are applied to bounded domains only. In this study, we propose an effective way to handle unbounded domains both with PD and classical diffusion models. For the former, we employ a meshfree discretization, whereas for the latter the finite element method (FEM) is employed. The proposed ABCs are time-dependent and Dirichlet-type, making the approach easy to implement in the available models. The performance of the approach, in terms of accuracy and stability, is illustrated by numerical examples in 1D, 2D, and 3D.

Whale optimization algorithm based on lateral inhibition for image matching and vision-guided AUV docking

2020 ◽  
pp. 1-12
Author(s):  
Zheping Yan ◽  
Jinzhong Zhang ◽  
Jialing Tang
Keyword(s):  
Lateral Inhibition ◽  
Optimization Algorithm ◽  
Image Matching ◽  
Autonomous Underwater Vehicle ◽  
Optimal Solution ◽  
Search Space ◽  
Whale Optimization Algorithm ◽  
Inhibition Mechanism ◽  
Whale Optimization ◽  
Accuracy And Stability

The accuracy and stability of relative pose estimation of an autonomous underwater vehicle (AUV) and a target depend on whether the characteristics of the underwater image can be accurately and quickly extracted. In this paper, a whale optimization algorithm (WOA) based on lateral inhibition (LI) is proposed to solve the image matching and vision-guided AUV docking problem. The proposed method is named the LI-WOA. The WOA is motivated by the behavior of humpback whales, and it mainly imitates encircling prey, bubble-net attacking and searching for prey to obtain the globally optimal solution in the search space. The WOA not only balances exploration and exploitation but also has a faster convergence speed, higher calculation accuracy and stronger robustness than other approaches. The lateral inhibition mechanism can effectively perform image enhancement and image edge extraction to improve the accuracy and stability of image matching. The LI-WOA combines the optimization efficiency of the WOA and the matching accuracy of the LI mechanism to improve convergence accuracy and the correct matching rate. To verify its effectiveness and feasibility, the WOA is compared with other algorithms by maximizing the similarity between the original image and the template image. The experimental results show that the LI-WOA has a better average value, a higher correct rate, less execution time and stronger robustness than other algorithms. The LI-WOA is an effective and stable method for solving the image matching and vision-guided AUV docking problem.

Salp swarm algorithm with crossover scheme and Lévy flight for global optimization

2021 ◽  
pp. 1-12
Author(s):  
Heming Jia ◽  
Chunbo Lang
Keyword(s):  
Global Optimization ◽  
Heuristic Algorithm ◽  
Experimental Results ◽  
High Dimensional ◽  
Lévy Flight ◽  
Test Functions ◽  
Levy Flight ◽  
Salp Swarm Algorithm ◽  
Swarm Algorithm ◽  
Accuracy And Stability

Salp swarm algorithm (SSA) is a meta-heuristic algorithm proposed in recent years, which shows certain advantages in solving some optimization tasks. However, with the increasing difficulty of solving the problem (e.g. multi-modal, high-dimensional), the convergence accuracy and stability of SSA algorithm decrease. In order to overcome the drawbacks, salp swarm algorithm with crossover scheme and Lévy flight (SSACL) is proposed. The crossover scheme and Lévy flight strategy are used to improve the movement patterns of salp leader and followers, respectively. Experiments have been conducted on various test functions, including unimodal, multimodal, and composite functions. The experimental results indicate that the proposed SSACL algorithm outperforms other advanced algorithms in terms of precision, stability, and efficiency. Furthermore, the Wilcoxon’s rank sum test illustrates the advantages of proposed method in a statistical and meaningful way.

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