Re: [Libmesh-users] Starting out with libmesh

[Roy S. <roy...@ic...>]

On Thu, 22 Mar 2018, Jorge Lopes wrote:

> 1) Understanding the structure of the documentation: It is highly
> non-trivial to browse through that.

It is; it's a half-decent reference but not a tutorial.

The closest thing we have to a tutorial is the examples, and even
there you have to skim descriptions and skip over the ones
focused on features you don't care about.

> I'm going to describe my problem and ask you to direct me to several
> relevant structures for me to get familiar with.
>
> 2) The problem I want to tackle is a combination of the Poisson equation
> and the Heat Equation.
> For a given time step we solve
> \nabla V = Source
> and use this to evolve to evolve the Heat-like equation
> i \partial \phi / \partial t = f(\phi, \phi', \phi'') + V \phi
> where \phi is a complex function, naturally.
>
> 3) I noted that libmesh has the 2 problems solved separately in
> examples/introduction/introduction_ex4 and somewhere in fem_systems. If
> this is useful, I'd have my problem half solved.
>
> All I'm looking for is some guidelines on how to start tackling the problem
> with my moderate knowledge of C++ and enormous difficulty in browsing
> through the documentation.

Two questions about your problem:

Do you want to solve it decoupled (e.g. if Source is independent of
phi, so you can get an exact value of V at each time step before
solving for phi) or (weakly or fully?) coupled?

Do you want to integrate with implicit time stepping, explicit, or
both?
---
Roy