Sökning: "Implicit Time-Stepping"

Visar resultat 1 - 5 av 17 avhandlingar innehållade orden Implicit Time-Stepping.

1. 1. Acceleration of Compressible Flow Simulations with Edge using Implicit Time Stepping

   Författare :Evelyn Otero; Arthur Rizzi; Jesper Oppelstrup; Per Wahlund; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; compressible CFD; convergence acceleration; implicit time-stepping; matrix dissipation; line-implicit; performance optimization;

   Sammanfattning : Computational fluid dynamics (CFD) has become a significant tool routinely used in design and optimization in aerospace industry. Typical flows may be characterized by high-speed and compressible flow features and, in many cases, by massive flow separation and unsteadiness. LÄS MER

3. 2. Acceleration of Compressible Flow Simulations with Edge Using  Implicit Time Stepping

   Författare :Evelyn Otero; Arthur Rizzi; Richard P. Dwight; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Compressible CFD; Convergence Acceleration; Implicit Time-Stepping; LU-SGS; Upwind Type Dissipation; Line-implicit; Ordering; Parallelization; Parameters; Multigrid;

   Sammanfattning : Computational fluid dynamics (CFD) is a significant tool routinely used indesign and optimization in aerospace industry. Often cases with unsteadyflows must be computed, and the long compute times of standard methods hasmotivated the present work on new implicit methods to replace the standardexplicit schemes. LÄS MER

4. 3. Multiresolution Continuum Theory Finite Element For Implicit Time Stepping Methods

   Författare :Hao Qin; Sebastian Skatulla; Luleå tekniska universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Material Mechanics; Materialmekanik;

   Sammanfattning : The multiresolution continuum theory is a higher order continuum theory where additional kinematic variables are added to account for the microstructural inhomogeneities at several distinct length scales. This can be particularly important for localization problems. LÄS MER

5. 4. Runge-Kutta Solution of Initial Value Problems: Methods, Algorithms and Implementation

   Författare :Hans Olsson; Institutionen för datavetenskap; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Computer science; stiffness; software; computational process; differential algebraic equations; ordinary differential equations; Runge-Kutta; initial value problems; time-stepping; system; kontroll; numerisk analys; Datalogi; control; numerical analysis; systems;

   Sammanfattning : The last decades have seen a strongly increasing use of computers for modeling larger and more complex systems. This has been made possible by a combination of increasing computer power and easy-to-use graphical modeling environments and libraries of components. LÄS MER

7. 5. Shape and material optimization for antenna applications

   Författare :Per Jacobsson; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; explicit-implicit time stepping; sensitivity analysis; Nitsche s method; total scattering cross section; shape and material optimization; array antennas; finite element method;

   Sammanfattning : In this thesis, a gradient-based method for shape and material optimization fortwo antenna applications is presented: minimization of the active reflectioncoefficient for conformal array antennas; and minimization of the totalscattering cross section for cylindrical scatterers. The sensitivity of theobjective function with respect to changes of the shape and material of the geometry isexpressed in terms of the original field problem and an adjoint field problem. LÄS MER