Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics Commons

Open Access. Powered by Scholars. Published by Universities.®

Articles 1 - 2 of 2

Full-Text Articles in Physical Sciences and Mathematics

Semi-Lagrangian Implicit Bhatnagar-Gross-Krook Collision Model For The Finite-Volume Discrete Boltzmann Method, Leitao Chen, Sauro Succi, Xiaofeng Cai, Laura Schaefer Jun 2020

Semi-Lagrangian Implicit Bhatnagar-Gross-Krook Collision Model For The Finite-Volume Discrete Boltzmann Method, Leitao Chen, Sauro Succi, Xiaofeng Cai, Laura Schaefer

Publications

In order to increase the accuracy of temporal solutions, reduce the computational cost of time marching, and improve the stability associated with collisions for the finite-volume discrete Boltzmann method, an advanced implicit Bhatnagar-Gross-Krook (BGK) collision model using a semi-Lagrangian approach is proposed in this paper. Unlike existing models, in which the implicit BGK collision is resolved either by a temporal extrapolation or by a variable transformation, the proposed model removes the implicitness by tracing the particle distribution functions (PDFs) back in time along their characteristic paths during the collision process. An interpolation scheme is needed to evaluate the PDFs at …


The Exotime Project: Signals In The O − C Diagrams Of The Rapidly Pulsating Subdwarfs Dw Lyn, V1636 Ori, Qq Vir, And V541 Hya, F. Mackebrandt, Terry Oswalt, S. Schuh, R. Silvotti, S. -L. Kim, D. Kilkenny, E. M. Green, R. Lutz, T. Nagel, J. L. Provencal, Tomomi Otani, S. Benatti, L. Lanteri, A. Bonanno, A. Frasca, R. Janulis, M. Paparó, L. Molnár, R. Claudi, R. H. Østensen Apr 2020

The Exotime Project: Signals In The O − C Diagrams Of The Rapidly Pulsating Subdwarfs Dw Lyn, V1636 Ori, Qq Vir, And V541 Hya, F. Mackebrandt, Terry Oswalt, S. Schuh, R. Silvotti, S. -L. Kim, D. Kilkenny, E. M. Green, R. Lutz, T. Nagel, J. L. Provencal, Tomomi Otani, S. Benatti, L. Lanteri, A. Bonanno, A. Frasca, R. Janulis, M. Paparó, L. Molnár, R. Claudi, R. H. Østensen

Publications

Aims. We aim to investigate variations in the arrival time of coherent stellar pulsations due to the light-travel time effect to test for the presence of sub-stellar companions. Those companions are the key to one possible formation scenario of apparently single sub-dwarf B stars. Methods. We made use of an extensive set of ground-based observations of the four large amplitude p-mode pulsators DW Lyn, V1636 Ori, QQ Vir, and V541 Hya. Observations of the TESS space telescope are available on two of the targets. The timing method compares the phase of sinusoidal fits to the full multi-epoch light curves with …