Re: [Libmesh-users] Explicit Central difference time integration

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

On Sat, 14 Oct 2017, Xiao Ma wrote:

> I am trying to solve a transient problem using explicit integration scheme
> (e.g central difference in time) with a lumpped mass technique solving a
> wave propagation problem.
>
> I am wondering if there is anything that is close to this purpose ?

Not to my knowledge.

> Due to the explicit integration scheme , I don't need to form a stiffness
> matrix K , so do I still need to use the Equationsystem class ?

Yes; you'll just need to make sure to only add ExplicitSystem-derived,
not ImplicitSystem-derived, systems to it.

> If I want to still use the Equationsystem class , is there a
> ExplcitTransient System available ?

Close: TransientExplicitSystem, in transient_system.h

> Bascily what I am gonna do is just :
>
> acceleration = F_ext./M_lumpped
> velocity = v_n+dt*accleration
> disp = u_n + dt*velocity
>
> The solve is just cwiseQuotient (coefficient wise Quotient product) of two
> vectors .

That all sounds reasonable.

You might run into performance issues, though.  Most libMesh users do
implicit solves exclusively, so we've never really heavily optimized
the library as used by an explicit application.  If performance turns
out to be a problem for you then let us know and we might be able to
help improve it.
---
Roy