scholarly journals Comparison of second-order mixed symplectic integrator between semi-implicit Euler method and implicit midpoint rule

2011 ◽  
Vol 60 (9) ◽  
pp. 090402
Author(s):  
Zhong Shuang-Ying ◽  
Wu Xin
Keyword(s):  
Euler Method ◽  
Second Order ◽  
Symplectic Integrator ◽  
Implicit Midpoint Rule ◽  
Midpoint Rule ◽  
Implicit Euler Method

scholarly journals Implicit Euler Method for Three-Dimensional Turbomachinery Flow Calculation

1993 ◽  
Author(s):  
Shih H. Chen ◽  
Anthony H. Eastland
Keyword(s):  
Three Dimensional ◽  
Prediction Method ◽  
Minimum Cost ◽  
Inviscid Flow ◽  
Turnaround Time ◽  
Euler Method ◽  
Second Order ◽  
Approximate Factorization ◽  
Implicit Euler Method ◽  
Numerical Instabilities

A compressible three-dimensional implicit Euler solution method for turbomachinery flows has been developed. The goal of the present study is to develop an efficient and reliable method that can be used to replace the semi-empirical, semi-analytical quasi-three-dimensional turbomachinery flow prediction method currently being used for multi-stage turbomachinery design at early design stages. Currently, a methodology has been developed based on an inviscid flow model (Euler solver) and tested on single blade rows for validation. The method presented here is derived from the Beam and Warming implicit approximate factorization (AF) finite difference algorithm. To avoid high frequency numerical instabilities associated with the use of central differencing schemes to obtain a spatial second order accuracy, a combined explicit and implicit artificial dissipation model is adopted. This model consists of a second order implicit dissipation and mixed second/fourth order explicit dissipation terms. A Cartesian coordinate H-grid generated by a three-dimensional interactive grid generator developed by Beach is used. Results for SSME High Pressure Fuel Turbine are presented and the comparison with experimental data is discussed. The use of the present implicit Euler method and the three-dimensional turbomachinery interactive grid generator shows that turnaround time could be as short as one day using a workstation. This allows the designers to explore optimal design configurations at minimum cost.

scholarly journals Draining of Water Tank using Runge-Kutta Methods

2020 ◽  
Vol 8 (5) ◽  
pp. 2342-2348
Keyword(s):  
Distribution System ◽  
Water Distribution ◽  
Euler Method ◽  
Water Tank ◽  
Implicit Midpoint Rule ◽  
Midpoint Rule ◽  
Runge Kutta ◽  
Fourth Order Method ◽  
Stability And Accuracy ◽  
Water Tanks

The use of water tanks as a tool for storing water before being distributed for daily use has become a widely used system today. Among the attempts to develop a water distribution system is optimization in terms of system and operating costs. In this study, four methods of the Runge Kutta method are the Implicit such as Explicit Euler method, Implicit Euler method, Implicit Midpoint Rule, Runge Kutta Fourth-order method are used and compared with the exact solution method. The method will be compared in terms of accuracy and efficiency in solving differential equations based on set parameters for optimum design of water tank. The accuracy and efficiency of each method can be determined based on error graph. At the end of the study, numerical results obtained indicate that the Implicit Midpoint Rule provides greater stability and accuracy for the fixed stepsize given compared to other numerical methods.

scholarly journals A First-Order Explicit-Implicit Splitting Method for a Convection-Diffusion Problem

2020 ◽  
Vol 20 (4) ◽  
pp. 769-782
Author(s):  
Amiya K. Pani ◽  
Vidar Thomée ◽  
A. S. Vasudeva Murthy
Keyword(s):  
Splitting Method ◽  
Diffusion Problem ◽  
Euler Method ◽  
Second Order ◽  
Time Step ◽  
Convection Diffusion ◽  
First Order ◽  
Backward Euler ◽  
Strang Splitting ◽  
Spatially Periodic

AbstractWe analyze a second-order in space, first-order in time accurate finite difference method for a spatially periodic convection-diffusion problem. This method is a time stepping method based on the first-order Lie splitting of the spatially semidiscrete solution. In each time step, on an interval of length k, of this solution, the method uses the backward Euler method for the diffusion part, and then applies a stabilized explicit forward Euler approximation on {m\geq 1} intervals of length {\frac{k}{m}} for the convection part. With h the mesh width in space, this results in an error bound of the form {C_{0}h^{2}+C_{m}k} for appropriately smooth solutions, where {C_{m}\leq C^{\prime}+\frac{C^{\prime\prime}}{m}}. This work complements the earlier study [V. Thomée and A. S. Vasudeva Murthy, An explicit-implicit splitting method for a convection-diffusion problem, Comput. Methods Appl. Math. 19 2019, 2, 283–293] based on the second-order Strang splitting.

scholarly journals Error estimates for forward Euler shock capturing finite element approximations of the one-dimensional Burgers' equation

2015 ◽  
Vol 25 (11) ◽  
pp. 2015-2042
Author(s):  
Erik Burman
Keyword(s):  
Finite Element ◽  
Error Estimates ◽  
Burgers Equation ◽  
Euler Method ◽  
Second Order ◽  
Shock Capturing ◽  
Discrete Solution ◽  
A Priori Bound ◽  
Forward Euler ◽  
Forward Euler Method

We propose an error analysis for a shock capturing finite element method for the Burgers' equation using the duality theory due to Tadmor. The estimates use a one-sided Lipschitz stability (Lip+-stability) estimate on the discrete solution and are obtained in a weak norm, but thanks to a total variation a priori bound on the discrete solution and an interpolation inequality, error estimates in Lp-norms (1 ≤ p < ∞) are deduced. Both first-order artificial viscosity and a nonlinear shock capturing term that formally is of second order are considered. For the discretization in time we use the forward Euler method. In the numerical section we verify the convergence order of the nonlinear scheme using the forward Euler method and a second-order strong stability preserving Runge–Kutta method. We also study the Lip+-stability property numerically and give some examples of when it holds strictly and when it is violated.

Nonlinear dynamic analysis of worn oil-lubricated rolling bearings

2020 ◽  
Vol 234 (2) ◽  
pp. 214-221
Author(s):  
Xue-Qian Fang ◽  
Fu-Ning Liu ◽  
Shao-Pu Yang
Keyword(s):  
Film Thickness ◽  
Nonlinear Dynamic ◽  
Significant Variation ◽  
Nonlinear Dynamic Analysis ◽  
Euler Method ◽  
Rolling Speed ◽  
Dynamic Equations ◽  
Rolling Bearings ◽  
Numerical Examples ◽  
Implicit Euler Method

Based on the elastohydrodynamic theory, the nonlinear dynamic behavior of worn oil-lubricated rolling bearings is explored, and the dynamic response including the effect of trajectory of the axis center, the accelerated speed, and the film thickness is analyzed. The worn model is represented by the worn depth. The discrete iterative method and implicit Euler method are combined to solve the dynamic equations. In numerical examples, the trajectory of the axis center, the accelerated speed and the film thickness under different worn depths are discussed. It is found that the stabilized point shows significant variation with the worn depth, and the wear effect is also quite related with the rolling speed. The trajectory of the axis center of worn bearing subjected to a step load is also examined in detail.

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