[BANANA] Berkeley Lab - Scientific Computing Seminar - Friday, 12/5/2008, 1:00pm

[Esmond G. Ng]

Berkeley Lab - Scientific Computing Seminar

Date:  Friday, December 5, 2008
Time:  1:00pm-2:00pm  
Location:  Building 50A, 5132 Conference Room

Seminar Speaker:
    Azzam Haidar
    University of Toulouse, INPT-ENSEEIHT, France

Title:  Parallel Hybrid Solver for Large 3D Problems

Abstract:

Large-scale scientific simulations are nowadays fully integrated in many 
scientific and industrial applications. Many of these simulations rely 
on modelisations based on PDEs that lead to the solution of huge linear 
or nonlinear systems of equations involving millions of unknowns. In 
that context the use of large high performance computers in conjunction 
with advanced fully parallel and scalable numerical techniques is 
mandatory to efficiently tackle these problems.

In this talk we consider the parallel scalability of variants of an 
algebraic additive Schwarz preconditioner for the solution of large 3D 
problems in a non-overlapping domain decomposition framework. To 
alleviate the computational cost, both in terms of memory and 
floating-point complexity, we investigate variants based on a sparse 
approximation or on mixed 32- and 64-bit calculation. The robustness and 
the scalability of the preconditioners are investigated through 
extensive parallel experiments on up to two thousand processors.

We represent also an approach based on two levels of parallelism, that 
offers the flexibility to combine the numerical and the parallel 
implementation scalabilities. The combination of the two levels of 
parallelism enables an optimal usage of the computing resource while 
preserving attractive numerical performance. Consequently such a 
numerical technique appears as a promising candidate for intensive 
simulations on massively parallel platforms.

The robustness and parallel numerical performance of the solver is 
reported on large challenging linear systems arising from the structural 
mechanics and seismic modeling applications.

(This is joint work with Luc Giraud.)

Sponsor of Seminar:  Sherry Li