Lab Home | Phone | Search
Center for Nonlinear Studies  Center for Nonlinear Studies
 Home 
 People 
 Current 
 Executive Committee 
 Postdocs 
 Visitors 
 Students 
 Research 
 Publications 
 Conferences 
 Workshops 
 Sponsorship 
 Talks 
 Seminars 
 Postdoc Seminars Archive 
 Quantum Lunch 
 Quantum Lunch Archive 
 P/T Colloquia 
 Archive 
 Ulam Scholar 
 
 Postdoc Nominations 
 Student Requests 
 Student Program 
 Visitor Requests 
 Description 
 Past Visitors 
 Services 
 General 
 
 History of CNLS 
 
 Maps, Directions 
 CNLS Office 
 T-Division 
 LANL 
 
Tuesday, November 05, 2024
11:00 AM - 12:00 PM
CNLS Conference Room (TA-3, Bldg 1690)

Seminar

A micro-macro decomposition for implicit time-stepping of the BGK model

Stefan Schnake
Oak Ridge National Laboratory

In this talk, we combine a high-order/low-order (HOLO) method with a micro-macro (MM) formulation to accelerate iterative solvers in fully implicit time stepping of the BGK equation for gas dynamics. The MM formulation represents a kinetic distribution as the sum of a local Maxwellian and a perturbation. In highly collisional regimes, the perturbation is small and can be compressed to reduce the overall storage cost of the distribution. The accuracy and performance of the MM-HOLO method is compared to the usual HOLO method and standard source iteration on a Sod shock tube problem and a sudden heating boundary layer problem. Both HOLO and MM-HOLO methods are implemented using a discontinuous (DG) discretization in phase space, which naturally preserves the consistency between high- and low-order models required by the HOLO approach. The compression enabled by the MM formulation is demonstrated as a function of the collision frequency.

Host: William T. Taitano (T-5)