China 
Africa 
Explore chapters and articles related to this topic
Atmospheric Dispersion with a Large-Eddy Simulation: Eulerian and Lagrangian Perspectives
Published in Davidson Moreira, Marco Vilhena, Air Pollution and Turbulence, 2009
Umberto Rizza, Giulia Gioia, Guglielmo Lacorata, Cristina Mangia, Gian Paolo Marra
As noted before, the pseudo-spectral method allows the application of periodic boundary conditions in both horizontal directions. Those fields that are provided in the output from one side of the domain are therefore used as input fields in the plane (x, y) for the opposite side of the domain. Even if periodic boundary conditions are convenient from a computational point of view, they are appropriate only for PBLs over homogeneous terrain.
Formation of Localized Nonlinear Waves in Layered Composites
Published in Igor V. Andrianov, Vladyslav Danishevskyy, Jan Awrejcewicz, Linear and Nonlinear Waves in Microstructured Solids, 2021
Igor V. Andrianov, Vladyslav Danishevskyy, Jan Awrejcewicz
Series (6.5) present a continuous approximation where the Runge-Kutta method is based on the discrete difference scheme. Combination of both approaches is named the pseudo-spectral method [175, 393]. The pseudo-spectral method has found the wide application while solving numerically nonlinear wave equations [69, 243, 395].
Investigation of the interfacial instability in a non-Boussinesq density stratified flow using linear stability theory
Published in Cogent Engineering, 2019
Ehsan Khavasi, Pouriya Amini, Javad Rahimi, Mohammad Hadi Mohammadi
Using linear stability method and normal modes, first, the instability equations were obtained for a double-layered flow with density layer and on an inclined bed. Using these equations, the flow stability was evaluated in the temporal framework. To solve the equations, the pseudo-spectral method with Chebyshev polynomials is used. The base velocity and concentration profiles were selected as hyperbolic tangent. The results of the present paper shows that instability characteristics of the stratified flow considering the non-Boussinesq regime is different from the cases with Boussinesq approximation (Khavasi et al., 2013). The results of the present paper can be useful in the prediction of the unstable modes in reality and designing experiments in which the Boussinesq approximation is meaningless. It is also shown that different parameters can affect the stability features of the stratified shear layers. The precise prediction of unstable waves can help the better understanding of influential parameters on mixing and entrainment.
MPI Parallel Implementation for Pseudo-Spectral Simulations for Turbulent Channel Flow
Published in International Journal of Computational Fluid Dynamics, 2020
Oh-Kyoung Kwon, Jin Lee, Junghoon Lee, Ji-Hoon Kang, Jung-Il Choi
In terms of parallelisation on distributed memory computing, the pseudo-spectral method is more difficult than the finite method. For example, the pseudo-spectral method requires information at all grid points in the wall-parallel plane for the Fourier transform, unlike the finite difference method, which requires information at adjacent grid points only. Transposing the computational domain that contains all information in the periodic direction requires a large amount of CPU time. In general, scalability decreases when using the Fourier transform, and greatly decelerates for very large computational domains owing to a very large number of grid points in the wall-parallel plane.