Implementation of a Numerical Scheme Based on the Dual Time Stepping in COSMO LM: Idealized Test Cases

2012 ◽  
Author(s):  
Giovanni Petrone
Keyword(s):  
Numerical Scheme ◽  
Test Cases ◽  
Time Stepping ◽  
Dual Time Stepping

scholarly journals A Coupled 1D-2D Hydrodynamic Model for Urban Flood Inundation

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Yuyan Fan ◽  
Tianqi Ao ◽  
Haijun Yu ◽  
Guoru Huang ◽  
Xiaodong Li
Keyword(s):  
Test Cases ◽  
Flood Inundation ◽  
Urban Floods ◽  
Urban Flood ◽  
Practical Applications ◽  
Time Stepping ◽  
Dual Time Stepping ◽  
Proposed Model ◽  
Saint Venant Equations ◽  
1D Model

Hydrodynamic models were commonly used for flood risk management in urban area. This paper presents initial efforts in developing an urban flood inundation model by coupling a one-dimensional (1D) model with a two-dimensional (2D) model to overcome the drawbacks of each individual modelling approach, and an additional module is used to simulate the rainfall-runoff process in study areas. For the 1D model, the finite difference method is used to discretize the Saint-Venant equations. An implicit dual time-stepping method (DTS) is then applied to a 2D finite volume model for an inundation simulation to improve computational efficiency. A total of four test cases are applied to validate the proposed model; its performance is demonstrated by a comparison with an explicit scheme and previously published results (an extensive physical experiment benchmark case, a vertical linking example, and two real drainage cases with actual topography). Results demonstrate that the proposed model is accurate and efficient in simulating urban floods for practical applications.

URANS Modeling of Three Airfoils With Different Stall Mechanisms

2008 ◽  
Author(s):  
M. Elkhoury ◽  
J. Najem ◽  
Z. Nakad
Keyword(s):  
Turbulence Model ◽  
Flow Separation ◽  
Numerical Scheme ◽  
Predictive Accuracy ◽  
Grid Size ◽  
Test Cases ◽  
Transition Effect ◽  
Time Stepping

Capability of recently developed Menter (ME) and Modified Menter (MME) one-equation models in predicting prestall and poststall characteristics of three airfoils that exhibit different stall onset mechanisms is investigated. The Spalart-Allmaras (SA) turbulence model is also included to form a baseline against which both the ME and the MME models are assessed. The effects of subiteration, grid size, and time stepping on the predictive accuracy of the numerical scheme are addressed. However, transition effect is not accounted for and hence, all test cases are run fully turbulent. Significant differences in the flow predictions of all models are noticed in regions with massively flow separation.

Improvements to a dual-time-stepping method for computating unsteady flows

AIAA Journal ◽  
1997 ◽  
Vol 35 ◽  
pp. 1548-1550 ◽  
Author(s):  
S. DeRango ◽  
D. W. Zingg
Keyword(s):  
Unsteady Flows ◽  
Time Stepping ◽  
Dual Time Stepping

scholarly journals Dual Time Stepping Algorithms With the High Order Harmonic Balance Method for Contact Interfaces With Fretting-Wear

2011 ◽  
Author(s):  
Loi¨c Salles ◽  
Laurent Blanc ◽  
Fabrice Thouverez ◽  
Alexander M. Gouskov ◽  
Pierrick Jean
Keyword(s):  
Frequency Domain ◽  
Dry Friction ◽  
Harmonic Balance ◽  
Harmonic Balance Method ◽  
Contact Forces ◽  
Balance Method ◽  
Fretting Wear ◽  
Rate Equations ◽  
Time Stepping ◽  
Dual Time Stepping

Contact interfaces with dry friction are frequently used in turbomachinery. Dry friction damping produced by the sliding surfaces of these interfaces reduces the amplitude of bladed-disk vibration. The relative displacements at these interfaces lead to fretting-wear which reduces the average life expectancy of the structure. Frequency response functions are calculated numerically by using the multi-Harmonic Balance Method (mHBM). The Dynamic Lagrangian Frequency-Time method is used to calculate contact forces in the frequency domain. A new strategy for solving non-linear systems based on dual time stepping is applied. This method is faster than using Newton solvers. It was used successfully for solving Nonlinear CFD equations in the frequency domain. This new approach allows identifying the steady state of worn systems by integrating wear rate equations a on dual time scale. The dual time equations are integrated by an implicit scheme. Of the different orders tested, the first order scheme provided the best results.

scholarly journals Splitting-particle methods for structured population models: Convergence and applications

2014 ◽  
Vol 24 (11) ◽  
pp. 2171-2197 ◽  
Author(s):  
J. A. Carrillo ◽  
P. Gwiazda ◽  
A. Ulikowska
Keyword(s):  
Numerical Scheme ◽  
Order Of Convergence ◽  
Operator Splitting ◽  
Population Models ◽  
Particle Simulation ◽  
Particle Methods ◽  
Test Cases ◽  
Structured Population Models ◽  
Convergence Error ◽  
Structured Population

We propose a new numerical scheme designed for a wide class of structured population models based on the idea of operator splitting and particle approximations. This scheme is related to the Escalator Boxcar Train (EBT) method commonly used in biology, which is in essence an analogue of particle methods used in physics. Our method exploits the split-up technique, thanks to which the transport step and the nonlocal integral terms in the equation can be separately considered. The order of convergence of the proposed method is obtained in the natural space of finite non-negative Radon measures equipped with the flat metric. This convergence is studied even adding reconstruction and approximation steps in the particle simulation to keep the number of approximation particles under control. We validate our scheme in several test cases showing the theoretical convergence error. Finally, we use the scheme in situations in which the EBT method does not apply showing the flexibility of this new method to cope with the different terms in general structured population models.

Sign in / Sign up

Export Citation Format

Share Document