Dissertation > Excellent graduate degree dissertation topics show

Investigations of Convergence Acceleration and Complex Flow Numerical Simulation for High-Order Accurate Scheme (WCNS)

Author: ZhangYiFeng
Tutor: DengXiaoGang
School: China Aerodynamics Research and Development Center
Course: Fluid Mechanics
Keywords: Higher order accuracy Susceptibility Flow Simulation Direct Numerical Simulation Flat plate boundary layer Timestep Doctoral Dissertation Turbulence model Applied Research Accelerate convergence
CLC: O35
Type: PhD thesis
Year: 2008
Downloads: 313
Quote: 4
Read: Download Dissertation

Abstract


As a class of numerical tools, high-order accurate scheme has been playing an important role in many calculation domains of science and technology, such as direct numerical simulation (DNS) and large eddy simulation (LES) for turbulence flows, computational AeroAcoustics (CAA), computational electro-magnetics (CEM) and magneto-hydrodynamic (MHD). Computations with high-order scheme can provide flow data and details for observations and analyses, and can make up for the limitations of wind-tunnel experiments and drawbacks of theories. Especially, with the increasing requirements for the accuracy of computations, more and more refined and exact numerical simulations are needed in application and research fields. In this context, high-order weighted compact nonlinear scheme (WCNS) is studied and applied further in this dissertation, and some valuable conclusions and computational experiences are obtained.The purpose of this thesis is to develop and exploit WCNS’s potential in practical computations, investigate its numerical characters in simulations of complex flows, and extend its application scope. Additionally, it is expected to improve understanding of some flow mechanisms, and bestead the future works about high-order accuracy computations.This thesis contains six chapters as follows:Chapter one is the introduction, in which the state of arts of high-order accurate scheme in computational fluid dynamics (CFD) are reviewed. This section presents the evolution and properties of WCNS and points out the handicap in applications. Also, this chapter narrates the meaning of WCNS for using in the complex flows of turbulence and boundary-layer receptivity. Finally, the current research works are described in brief.Chapter two presents the numerical methods used in this dissertation. The main contents include: governing equations, space discretization, time integration, boundary conditions, turbulence models and aerodynamic coefficient formulas.In chapter three, a number of different implicit time methods are compared with each other for several supersonic flows over cylinder and sphere, when the high-order scheme of WCNS-E-5 is used in the discretization of space terms. The time methods involve LU-SGS, Gauss-Seidel point relaxation and line relaxation, and generalized minimum residual (GMRES) algorithm. To evaluate convergence of time methods, the influences of many factors including time step, sub-iteration number and precondition method of GMRES, are considered in the numerical experiments. The results show that the using of accurate analytical Jacobians in the left hand of discretized equations can improve the convergence of WCNS-E-5, and the GMRES method can accelerate the converging process further. And, these methods are successfully employed in more complex hypersonic flows over double-ellipse.In chapter four, the discrepancies in turbulence simulation between five-order accurate scheme WCNS-E-5 and two-order accurate scheme MUSCL are researched in the numerical cases of transonic flows over RAE2822 airfoil and M6 wing and low-speed high-attack-angle separation flows over slender cylinder. The effects induced from grids, inviscous flux formulas and turbulence models are carefully investigated with comparisons. The preliminary results indicate that the dissipation error level of numerical scheme has remarkable influence on the simulations of turbulent flows, and that the computation of high-order scheme WCNS is affected little by the factors except for turbulence models. Therefore, high-order scheme can obtain more reliable and accurate turbulence solutions and do more benefits for turbulence modeling.In chapter five, WCNS-E-5 is applied to directly simulating the receptivity processes of hypersonic boundary-layer to acoustic disturbance. The receptivity case of parabola leading-edge is adopted to validate the spatial resolution of WCNS-E-5. The temporal resolution and efficiency of single-time-step implicit scheme are also studied in contrast with Runge-Kutta explicit time scheme. It is found that the space and time methods employed in this thesis are accurate enough and highly efficient. Using these methods, a series of receptivity simulations for flat plate boundary-layer to two-dimension acoustic wave are systemically carried out with consideration of many parameter effects involving wall cooling, fast/slow wave, incidence angle and leading-edge thickness. From these massive calculations, the understanding of physical process is improved and some meaningful conclusions are achieved for receptivity researches.Chapter six reviews all works in this dissertation and gives the concluding remarks and the future research directions.Finally, the references and acknowledgements are presented.

Related Dissertations

  1. The Application Study of Lao Tze Thought in the Chinese Teaching of Middle School,G633.3
  2. Application of Ascending-Descending Theory in Treatment of Chronic Renal Failure,R277.5
  3. The Applied Research on Inquiry Teaching in Wushu Courses of Physical Education,G852-4
  4. Assessment of Resistance Risk in Spodoptera Exigua (Hubner) and Spodoptera Litura (Lepidoptera: Noctuidae) to Chlorantraniliprole,S433
  5. Mineralogical and Geochemical Evidence of the Presence of Ancient Paddy Soil Layer in Chuodun Ancient Agricultural Site, Kunshan,S-09
  6. Susceptibilities to Four Neonicotinoids and Related Tolerant Mechanisms in Colorado Potato Beetles (Leptinotarsa Decemlineata),S435.32
  7. Studies on the Differences of Tolerance between Chilo Supperssalis Walker and Sesamia Inferens Walker to Bt Rice,S435.112.1
  8. Toxicities of Several Newly-Typed Insecticides to Colorado Potato Beetle, Leptinotarsa Decemlineata (Say) and Molecular Cloning of Two Kinds of Targets,S435.32
  9. Determining Insecticde Susceptibility and Laboratory Screening for Combined Insecticide to Leaffolder, Cnaplocrocis Medinalis (Guenee) (Lepidoptera: Pyralidae),S482.3
  10. Combined Study of Susceptibility Weighted Imaging and Dynamical Susceptibility Contrasted Perfusion Imaging in Detection of Heterogeneity of Brain Neoplasms,R739.4
  11. In Vitro State the Experiment Study of the Arterial Blood Gas Level and the Arterial Thrombus Volume by MRI,R445.2
  12. Preliminary Study of Molecular Epidemiology on Hepatitis B among Certain Regions in Anhui Province,R512.62
  13. A Case Control Study of Cognitive Change for Higher and Lower Hypnotic Susceptible Group after Hypnotic Suggestion,R749
  14. Research on Cooperative Learning in the Junior High School Biology Teaching,G633.91
  15. Antibiotic-resistance of Helicobacter Pylori and Effects of Helicobacter Pylori Eradication on Different Subtypes of Functional Dyspepsia,R57
  16. Experimental Study Saline Subbase with Calcium Carbide Dust,U412.22
  17. Jiangxi University Office Hours regime applied research,G434
  18. Low carbon concept in Tourism Planning Application,F592;F205
  19. Six Sigma management in the telecommunications base stations Fault Management Application,TN929.5
  20. Spreading green technology research facilities Yushan,S571.1
  21. Dynamic teaching game mode in college Volleyball Teaching Research,G842-4

CLC: > Mathematical sciences and chemical > Mechanics > Fluid Mechanics
© 2012 www.DissertationTopic.Net  Mobile