• Title/Summary/Keyword: WENO schemes

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Development of a High-Order Accurate Hybrid Scheme Using the Central Flux and WENO Schemes (Central Flux Scheme과 WENO Scheme을 이용한 고차 정확도 Hybrid Scheme의 개발)

  • Kim D.;Kwon J. H.
    • 한국전산유체공학회:학술대회논문집
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    • 2005.04a
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    • pp.135-141
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    • 2005
  • A hybrid central-WENO scheme is proposed. The fifth order WENO-LF scheme is coupled with a central flux scheme at cell face. Two sub-schemes, the WENO-LF scheme and the central flux scheme, are switched by a weighting function. The efficiency and accuracy of the proposed hybrid central-WENO scheme is validated through several numerical experiments.

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Preconditioned Jacobian-free Newton-Krylov fully implicit high order WENO schemes and flux limiter methods for two-phase flow models

  • Zhou, Xiafeng;Zhong, Changming;Li, Zhongchun;Li, Fu
    • Nuclear Engineering and Technology
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    • v.54 no.1
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    • pp.49-60
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    • 2022
  • Motivated by the high-resolution properties of high-order Weighted Essentially Non-Oscillatory (WENO) and flux limiter (FL) for steep-gradient problems and the robust convergence of Jacobian-free Newton-Krylov (JFNK) methods for nonlinear systems, the preconditioned JFNK fully implicit high-order WENO and FL schemes are proposed to solve the transient two-phase two-fluid models. Specially, the second-order fully-implicit BDF2 is used for the temporal operator and then the third-order WENO schemes and various flux limiters can be adopted to discrete the spatial operator. For the sake of the generalization of the finite-difference-based preconditioning acceleration methods and the excellent convergence to solve the complicated and various operational conditions, the random vector instead of the initial condition is skillfully chosen as the solving variables to obtain better sparsity pattern or more positions of non-zero elements in this paper. Finally, the WENO_JFNK and FL_JFNK codes are developed and then the two-phase steep-gradient problem, phase appearance/disappearance problem, U-tube problem and linear advection problem are tested to analyze the convergence, computational cost and efficiency in detailed. Numerical results show that WENO_JFNK and FL_JFNK can significantly reduce numerical diffusion and obtain better solutions than traditional methods. WENO_JFNK gives more stable and accurate solutions than FL_JFNK for the test problems and the proposed finite-difference-based preconditioning acceleration methods based on the random vector can significantly improve the convergence speed and efficiency.

ADAPTIVE MESH REFINEMENT FOR WEIGHTED ESSENTIALLY NON-OSCILLATORY SCHEMES

  • Yoon, Dae-Ki;Kim, Hong-Joong;Hwang, Woon-Jae
    • Bulletin of the Korean Mathematical Society
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    • v.45 no.4
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    • pp.781-795
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    • 2008
  • In this paper, we describe the application procedure of the adaptive mesh refinement (AMR) for the weighted essentially non-oscillatory schemes (WENO), and observe the effects of the derived algorithm when problems have piecewise smooth solutions containing discontinuities. We find numerically that the dissipation of the WENO scheme can be lessened by the implementation of AMR while the accuracy is maintained. We deduce from the experiments that the AMR-implemented WENO scheme captures shocks more efficiently than the WENO method using uniform grids.

NUMERICAL COMPARISON OF WENO TYPE SCHEMES TO THE SIMULATIONS OF THIN FILMS

  • Kang, Myungjoo;Kim, Chang Ho;Ha, Youngsoo
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.16 no.3
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    • pp.193-204
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    • 2012
  • This paper is comparing numerical schemes for a differential equation with convection and fourth-order diffusion. Our model equation is $h_t+(h^2-h^3)_x=-(h^3h_{xxx})_x$, which arises in the context of thin film flow driven the competing effects of an induced surface tension gradient and gravity. These films arise in thin coating flows and are of great technical and scientific interest. Here we focus on the several numerical methods to apply the model equation and the comparison and analysis of the numerical results. The convection terms are treated with well known WENO methods and the diffusion term is treated implicitly. The diffusion and convection schemes are combined using a fractional step-splitting method.

COMPARISON BETWEEN THE POSITIVE SCHEMES AND WENO FOR HIGH MACH JETS IN 1D

  • Ha, Young-Soo
    • Communications of the Korean Mathematical Society
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    • v.22 no.4
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    • pp.609-621
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    • 2007
  • Comparison of high Mach number jets using positive schemes and Weighted ENO methods is considered in this paper. The positive scheme introduced by [11, 14] and Weighted ENO [9, 10] have allowed us to simulate very high Mach numbers more than Mach 80. Simulations at high Mach numbers and with radiative cooling are essential for achieving detailed agreement with astrophysical images.

Supersonic Base Flow by Using High Order Schemes

  • Shin, Edward Jae-Ryul;Won, Su-Hee;Cho, Doek-Rae;Choi, Jeong-Yeol
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2008.03a
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    • pp.723-728
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    • 2008
  • We performed numerical analysis of base drag phenomenon, when a projectile with backward step flies into atmosphere at supersonic speed. We compared with other researchers. From our previous studies that were 2-dimensional simulation, we found out from sophisticated simulations that need dense mesh points to compare base pressure and velocity profile after from base with experimental data. Therefore, we focus on high order spatial disceretization over 3rd order with TVD such as MUSCL TVD 3rd, 5th, and WENO 5th order, and Limiters such as minmod, Triad. Moreover, we enforce to flux averaging schemes such as Roe, RoeM, HLLE, AUSMDV. In present, one dimensional result of Euler tests, there are Sod, Lax, Shu-Osher and interacting blast wave problems. AUSMDV as a flux averaging scheme with MUSCL TVD 5th order as spatial resolution is good agreement with exact solutions than other combinations. We are carrying out the same approaches into 3-dimensional base flow only candidate flux schemes that are Roe, AUSMDV. Additionally, turbulence models are used in 3-dimensional flow, one is Menter s SST DES model and another is Sparlat-Allmaras DES/DDES model in Navier-Stokes equations.

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Numerical Simulations for Magnetohydrodynamics based on Upwind Schemes

  • Jang, Hanbyul;Ryu, Dongsu
    • The Bulletin of The Korean Astronomical Society
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    • v.39 no.2
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    • pp.119.2-119.2
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    • 2014
  • Many astrophysical phenomena involve processes of magnetohydrodynamics (MHD) and relativistic magnetohydrodynamics (RMHD). A number of numerical schemes have been developed to solve the equations of ideal MHD and RMHD. Recent codes are based on upwind schemes which solve hyperbolic systems of equations following the characteristics of the systems. Upwind schemes stand out by their robustness, clarity of the underlying physical model, and ability of achieving high resolution. We present MHD and RMHD codes based on the total variation diminishing (TVD) and weighted essentially non-oscillatory (WENO) schemes, which are second and higher order accurate extensions of upwind schemes. We demonstrate the ability and limitation of codes based on upwind schemes through a series of tests.

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AN IMPROVED ALTERNATIVE WENO SCHEMES WITH PERTURBATIONAL TERMS FOR THE HYPERBOLIC CONSERVATION LAWS

  • KUNMIN SUNG;YOUNGSOO HA;MYUNGJOO KANG
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.27 no.4
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    • pp.207-231
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    • 2023
  • This paper aims to improve the alternative formulation of the fifth- and sixth-order accurate weighted essentially non-oscillatory (AWENO) finite difference schemes. The first is to derive the AWENO scheme with sixth-order accuracy in the smooth region of the solution. Second, a new weighted polynomial functions combining the perturbed forms with conserved variable to the AWENO is constructed; the new form of tunable functions are invented to maintain non-oscillatory property. Detailed numerical experiments are presented to illustrate the behavior of the new perturbational AWENO schemes. The performance of the present scheme is evaluated in terms of accuracy and resolution of discontinuities using a variety of one and two-dimensional test cases. We show that the resulted perturbational AWENO schemes can achieve fifth- and sixth-order accuracy in smooth regions while reducing numerical dissipation significantly near singularities.

Study on the Phase Interface Tracking Numerical Schemes by Level Set Method (Level Set 방법에 의한 상경계 추적 수치기법 연구)

  • Kim, Won-Kap;Chung, Jae-Dong
    • Proceedings of the SAREK Conference
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    • 2006.06a
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    • pp.116-121
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    • 2006
  • Numerical simulations for dendritic growth of crystals are conducted in this study by the level set method. The effect of order of difference is tested for reinitialization error in simple problems and authors founded in case of 1st order of difference that very fine grids have to be used to minimize the error and higher order of difference is desirable to minimize the reinitialization error The 2nd and 4th order Runge-Kutta scheme in time and 3rd and 5th order of WENO schemes with Godunov scheme are applied for space discretization. Numerical results are compared with the analytical theory, phase-field method and other researcher's level set method.

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MULTIDIMENSIONAL INTERPOLATIONS FOR THE HIGH ORDER SCHEMES IN ADAPTIVE GRIDS (적응 격자 고차 해상도 해법을 위한 다차원 내삽법)

  • Chang, S.M.;Morris, P.J.
    • Journal of computational fluids engineering
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    • v.11 no.4 s.35
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    • pp.39-47
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    • 2006
  • In this paper, the authors developed a multidimensional interpolation method inside a finite volume cell in the computation of high-order accurate numerical flux such as the fifth order WEND (weighted essentially non-oscillatory) scheme. This numerical method starts from a simple Taylor series expansion in a proper spatial order of accuracy, and the WEND filter is used for the reconstruction of sharp nonlinear waves like shocks in the compressible flow. Two kinds of interpolations are developed: one is for the cell-averaged values of conservative variables divided in one mother cell (Type 1), and the other is for the vertex values in the individual cells (Type 2). The result of the present study can be directly used to the cell refinement as well as the convective flux between finer and coarser cells in the Cartesian adaptive grid system (Type 1) and to the post-processing as well as the viscous flux in the Navier-Stokes equations on any types of structured and unstructured grids (Type 2).