Applications of the PRESB Preconditioning Method for OPT-PDE Problems

2020 ◽  
pp. 73-81
Author(s):  
Owe Axelsson
Keyword(s):  
Preconditioning Method

Numerical Method for Simulating Flows of Supercritical CO2 Compressor With Nonequilibrium Condensation

2016 ◽  
Author(s):  
Takashi Furusawa ◽  
Hironori Miyazawa ◽  
Satoru Yamamoto
Keyword(s):  
Numerical Method ◽  
Supercritical Co2 ◽  
Mass Fraction ◽  
Leading Edge ◽  
Pressure Variation ◽  
Supercritical Pressure ◽  
Local Region ◽  
Preconditioning Method ◽  
Condensation Model ◽  
Nonequilibrium Condensation

We recently proposed a numerical method for simulating flows of supercritical CO2 based on a preconditioning method and the thermophysical models programed in a program package for thermophysical properties of fluids (PROPATH). In this study, this method is applied to the investigation of cascade channel. Numerical results obtained by assuming supercritical pressure conditions indicate that the normal shock generated in the cascade channel deeply depends on the pressure condition. In particular, the speed of sound varying with the pressure variation at the supercritical state is a key thermophysical property which changes the flow field in the cascade channel. In addition, we also simulate those flows with nonequilibrium condensation in which the inlet pressure and temperature approaching to those of the critical point are specified. Then a nonequilibrium condensation model developed by our group is further applied to the numerical method. CO2 condensation observed in a case indicates that condensation occurs at a local region near the leading edge due to the flow expansion; the droplets soon grow at the local region and streams downward with keeping almost the same mass fraction.

scholarly journals Application of Hierarchical Two-Level Spectral Preconditioning Method for Electromagnetic Scattering from the Rough Surface

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
D. Z. Ding ◽  
G. M. Li ◽  
Y. Y. An ◽  
R. S. Chen
Keyword(s):  
Rough Surface ◽  
Electromagnetic Scattering ◽  
Fast Multipole Method ◽  
Scattering Problems ◽  
Approximate Inverse ◽  
Sparse Approximate Inverse ◽  
Preconditioning Method ◽  
Speed Up ◽  
Spectral Preconditioner ◽  
Field Integral

The higher-order hierarchical Legendre basis functions combining the electrical field integral equations (EFIE) are developed to solve the scattering problems from the rough surface. The hierarchical two-level spectral preconditioning method is developed for the generalized minimal residual iterative method (GMRES). The hierarchical two-level spectral preconditioner is constructed by combining the spectral preconditioner and sparse approximate inverse (SAI) preconditioner to speed up the convergence rate of iterative methods. The multilevel fast multipole method (MLFMM) is employed to reduce memory requirement and computational complexity of the method of moments (MoM) solution. The accuracy and efficiency are confirmed with a couple of numerical examples.

Stepwise Rising CO2Insufflation as an Ischemic Preconditioning Method

2007 ◽  
Vol 17 (6) ◽  
pp. 723-730 ◽  
Author(s):  
Dursun A. Sahin ◽  
Berna Haliloglu ◽  
Figen Kir Ahin ◽  
Gokhan Akbulut ◽  
Huseyin Fidan ◽  
...  
Keyword(s):  
Ischemic Preconditioning ◽  
Preconditioning Method
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