scholarly journals Computation of clear-air radar backscatter from numerical simulations of turbulence: 1. Numerical methods and evaluation of biases

2011 ◽  
Vol 116 (D21) ◽  
Author(s):  
P. M. Franke ◽  
S. Mahmoud ◽  
K. Raizada ◽  
K. Wan ◽  
D. C. Fritts ◽  
...  
Keyword(s):  
Numerical Methods ◽  
Numerical Simulations ◽  
Radar Backscatter

Turbulent Flows with Drops and Bubbles: What Numerical Simulations Can Tell Us – Freeman Scholar Lecture

2021 ◽  
Author(s):  
Giovanni Soligo ◽  
Alessio Roccon ◽  
Alfredo Soldati
Keyword(s):  
Numerical Methods ◽  
Best Practices ◽  
Numerical Simulations ◽  
Turbulent Flows ◽  
Multiphase Flows ◽  
Simulation Analysis ◽  
Droplet Size Distribution ◽  
Limited Range ◽  
Numerical Resolution ◽  
Multi Scale

Abstract Turbulent flows laden with large, deformable drops or bubbles are ubiquitous in nature and in a number of industrial processes. These flows are characterized by a physics acting at many different scales: from the macroscopic length scale of the problem down to the microscopic molecular scale of the interface. Naturally, the numerical resolution of all the scales of the problem, which span about eight to nine orders of magnitude, is not possible, with the consequence that numerical simulations of turbulent multiphase flows impose challenges and require methods able to capture the multi-scale nature of the flow. In this review, we start by describing the numerical methods commonly employed and discussing their advantages and limitations, and then we focus on the issues arising from the limited range of scales that can be possibly solved. Ultimately, the droplet size distribution, a key result of interest for turbulent multiphase flows, is used as a benchmark to compare the capabilities of the different methods and to discuss the main insights that can be drawn from these simulations. Based on this, we define a series of guidelines and best practices that we believe important in the simulation analysis and in the development of new numerical methods.

scholarly journals Experimental and Numerical Research on Cylindrical Tubes under Outer Cylindrical Explosive Waves

2017 ◽  
Vol 2017 ◽  
pp. 1-10
Author(s):  
Sui Yaguang ◽  
Zhang Dezhi ◽  
Tang Shiying ◽  
Chen Bo
Keyword(s):  
Numerical Methods ◽  
Numerical Simulations ◽  
Explosive Loading ◽  
Important Application ◽  
Uniform Deformation ◽  
Collision Region ◽  
Explosive Wave ◽  
Cylindrical Tubes ◽  
Numerical Research ◽  
Microscopic Deformation

Cylindrical explosive loading has an important application in explosive working, researching on weapon damage, and explosive-driving load. This study uses experimental and numerical methods to study the response of long and thin tubes when subjected to cylindrical explosive loading. The flake-like charge and multipoint initiation technique were adopted to load cylindrical explosive waves. Experimental results showed that the method could produce uniform deformation in certain parts of the long tube, but partial spall injuries occurred after the explosion. The macroscopic and microscopic deformation of tubes were analyzed. Numerical simulations were conducted to investigate the detailed response of the tube subjected to a cylindrical explosive wave. The results indicate that the collision of explosive waves brought inconsistencies in pressure and velocity. The pressure and velocity in the collision region were significantly higher than those of other parts, which caused the collision region to be easily damaged.

A numerical framework for the approximate solution of fractional tumor-obesity model

2019 ◽  
Vol 10 (01) ◽  
pp. 1941008 ◽  
Author(s):  
Sadia Arshad ◽  
Dumitru Baleanu ◽  
Ozlem Defterli ◽  
Shumaila
Keyword(s):  
Immune Response ◽  
Approximate Solution ◽  
Numerical Methods ◽  
Numerical Simulations ◽  
Fractional Order ◽  
Response Rate ◽  
Stability And Convergence ◽  
Fractional Operators ◽  
High Caloric Diet

In this paper, we have proposed the efficient numerical methods to solve a tumor-obesity model which involves two types of the fractional operators namely Caputo and Caputo-Fabrizio (CF). Stability and convergence of the proposed schemes using Caputo and CF fractional operators are analyzed. Numerical simulations are carried out to investigate the effect of low and high caloric diet on tumor dynamics of the generalized models. We perform the numerical simulations of the tumor-obesity model for different fractional order by varying immune response rate to compare the dynamics of the Caputo and CF fractional operators.

scholarly journals Note on the Sensitivity of Simulated Solutions of the Nonlinear Singularly Perturbed Dynamical System on the Used Different Rewriting into a System of First Order Differential Equations

2016 ◽  
Vol 24 (39) ◽  
pp. 51-55
Author(s):  
Vladimír Liška ◽  
Zuzana Šútova ◽  
Dušan Pavliak
Keyword(s):  
Dynamical System ◽  
Numerical Methods ◽  
Differential Equations ◽  
Numerical Simulations ◽  
Numerical Scheme ◽  
Singularly Perturbed ◽  
First Order ◽  
First Order Differential Equations

Abstract In this paper we analyze the sensitivity of solutions to a nonlinear singularly perturbed dynamical system based on different rewriting into a System of the First Order Differential Equations to a numerical scheme. Numerical simulations of the solutions use numerical methods implemented in MATLAB.

scholarly journals Predicting multiple planet stability and habitable zone companions in the TESS era

2019 ◽  
Vol 485 (4) ◽  
pp. 4703-4725 ◽  
Author(s):  
Matthew T Agnew ◽  
Sarah T Maddison ◽  
Jonathan Horner ◽  
Stephen R Kane
Keyword(s):  
Numerical Methods ◽  
Numerical Simulations ◽  
Dynamical Stability ◽  
Habitable Zone ◽  
Stable Orbit ◽  
Predictive Tool ◽  
Resonant Orbits ◽  
Test Particles ◽  
The Stability ◽  
Unique Signature

Abstract We present an approach that is able to both rapidly assess the dynamical stability of multiple planet systems, and determine whether an exoplanet system would be capable of hosting a dynamically stable Earth-mass companion in its habitable zone (HZ). We conduct a suite of numerical simulations using a swarm of massless test particles (TPs) in the vicinity of the orbit of a massive planet, in order to develop a predictive tool which can be used to achieve these desired outcomes. In this work, we outline both the numerical methods we used to develop the tool, and demonstrate its use. We find that the TPs survive in systems either because they are unperturbed due to being so far removed from the massive planet, or due to being trapped in stable mean-motion resonant orbits with the massive planet. The resulting unexcited TP swarm produces a unique signature in (a, e) space that represents the stable regions within the system. We are able to scale and translate this stability signature, and combine several together in order to conservatively assess the dynamical stability of newly discovered multiple planet systems. We also assess the stability of a system’s HZ and determine whether an Earth-mass companion could remain on a stable orbit, without the need for exhaustive numerical simulations.

NUMERICAL STUDIES OF PHASE TRANSITIONS AND CRITICAL PHENOMENA IN LIQUID CRYSTALS

1995 ◽  
Vol 09 (18n19) ◽  
pp. 2219-2245 ◽  
Author(s):  
CHANDAN DASGUPTA
Keyword(s):  
Phase Transitions ◽  
Liquid Crystals ◽  
Numerical Methods ◽  
Numerical Simulations ◽  
Critical Phenomena ◽  
Numerical Studies ◽  
Future Work

This article contains an overview of numerical simulations of phase transitions and critical phenomena in liquid crystals. After a brief description of the models studied in simulations and an elementary introduction to commonly used numerical methods, results obtained from existing numerical studies of phase transitions and critial phenomena in liquid crystals are reviewed and some directions for future work are suggested.

scholarly journals Boundary conditions for semi-Lagrangian methods for the BGK model

2016 ◽  
Vol 7 (3) ◽  
pp. 138-164 ◽  
Author(s):  
Maria Groppi ◽  
Giovanni Russo ◽  
Giuseppe Stracquadanio
Keyword(s):  
Boltzmann Equation ◽  
Numerical Methods ◽  
Boundary Conditions ◽  
Numerical Simulations ◽  
Lagrangian Formulation ◽  
High Order Accuracy ◽  
Bgk Model ◽  
Order Accuracy ◽  
New Class ◽  
Iterative Procedures

Abstract A new class of high-order accuracy numerical methods based on a semi-Lagrangian formulation for the BGK model of the Boltzmann equation has been recently proposed in [1]. In this paper semi-Lagrangian schemes for the BGK equation have been extended to treat boundary conditions, in particular the diffusive ones. Two different techniques are proposed, using or avoiding iterative procedures. Numerical simulations illustrate the accuracy properties of these approaches and the agreement with the results available in literature.

scholarly journals Estimating the execution time of fully-online multiscale numerical simulations

2020 ◽  
Author(s):  
Juan Fabian ◽  
Antônio Gomes ◽  
Eduardo Ogasawara
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Numerical Methods ◽  
Numerical Simulations ◽  
Learning Process ◽  
Execution Time ◽  
Prediction Models ◽  
Computational Effort ◽  
Multiscale Numerical Methods ◽  
Element Method

In this paper, we propose a methodology for estimating the execution time of simulations driven by multiscale numerical methods. The methodology explores the idiosyncrasies of multiscale simulators to reduce the uncertainty of predictions. We use the multiscale hybrid-mixed (MHM) finite element method to validate our methodology. We compare our proposed technique with prediction models automatically selected and calibrated by Auto-WEKA. We show that the models obtained with our technique are competitive when compared with the models coming from Auto-WEKA, being interpretable and with much less computational effort during the learning process.

Numerical Simulations for the Response of a Submerged Horizontal Cylinder Moored in Waves: COER Hydrodynamic Modeling Competition

2015 ◽  
Author(s):  
Dong-Hyun Lim ◽  
Taeyoung Kim ◽  
Yonghwan Kim
Keyword(s):  
Numerical Methods ◽  
Numerical Simulations ◽  
Potential Theory ◽  
Horizontal Cylinder ◽  
Hydrodynamic Modeling ◽  
Viscous Damping ◽  
Computational Results ◽  
Hydrodynamic Behavior ◽  
Reasonable Degree ◽  
Input Wave

The hydrodynamic behavior of a submerged horizontal cylinder moored in waves was studied through numerical methods as a participant of the COER Hydrodynamic Modeling Competition. The potential theory with additional viscous damping has been used to model the problem. Three different simulation cases have been constructed to identify (i) the general behaviors of the cylinder subjected to the input wave, (ii) the effect of the second-order hydrodynamic forces, and (iii) the effect of exact wetted surface issue. Computational results were compared to the experiment, and a reasonable degree of accuracy has been confirmed.

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