Skip to main content

Hybrid Solvers

For the moment, I am developing an Non-Overlapping Domain Decomposition Hybrid Solver for scalar PDE in 2D/3D domains.

It decomposes the underlying mesh into regions, solves the Schur Complement System onto frontier nodes between regions and then solves the problem into each inner region nodes.

This type of solver is said to be HYBRID because the Schur complement system is solved by a preconditioned iterative method whereas the inner problems are solved by a direct method. So it mixes the approach. However it requires less memory (and possibly time) than any direct solvers and in the same time suffer less of bad conditioning than iterative ones (the Schur complement system is well conditioned in that case).

This technique allows to split computation easily since each regions are more or less independent during all the process. It has been used with success on computer clusters, and I wish to use it with shared memory paradigm in mind to solve huge systems on (relatively modest) desktop computers.

In some time I will report my advance here, and the capabilities of the code I am developing, with performance profiles.

Comments

Popular posts from this blog

Shear waves, medecine and brain

Yesterday evening, too bored by what TV was proposing to me, I decided to watch a conference of Mathias Fink , a french researcher working on multidisciplinary application of waves. Specially shear waves.  Here is a brief summary of his talk. In solids, waves have two principal components:  compression waves (P-waves for primary) moving in the direction of propagation, and shear waves (S-waves, for secondary) that make ripples in the plane orthogonal to that direction. Since compression waves propagate in the direction of propagation, they move faster than shear waves. Usually ultrasound equipment in medicine only use compressional waves. But since human tissues have a high bulk modulus, the P-wave speed is relatively constant (around 1580 m/s). Human tissues are very stiff if you apply isotropic constraints on them (like pressure of water). However M. Fink and his colleagues proposed a new way to investigate human tissues by first sending a strong compressional wave in ...

I will play lego forever !

For our greatest delight (at least mine), Andrew Lipson is a crazy guy. He's building many funny things in Lego. Like topological surfaces, Klein bottle, from the in/out-side ! Escher pictures, waterfall Or scultpures, like Rodin's thinker However, lego construction may be a way to counter-act the financial crisis which has the inconvenient to cut funding in research laboratory. For instance, Daniel strange (I don't invent anything !) built and programmed a crane that moves in a set path, raising and lowering the sample between beakers containing solutions using a Lego Mindstorms NXT kit. Neat.

Alexandre's post-it dodecahedron

This magnifical (I had english lessons with Sarkozy) sculpture is the artwork of one of my co-worker, Alexandre. He got the blueprint from here: http://www.youtube.com/watch?v=vjOOhemquss Think it's better than post-it war! http://www.postitwar.com/page/2