Re: [Libmesh-users] A question for the ordering of unknowns

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

On Mon, 25 May 2020, Li Luo wrote:

> For a multicomponent system, such as Navier-Stokes equations, I found that
> the ordering of unknowns in the system depends on the order of polynomials
> used for the variables. Take a two-component system with variables u and p
> for example:
>   -If using first order for both variables, the ordering is point by
> point, that is u_1, p_1, u_2, p_2, ...., u_n, p_n.
>   -If using second order for u and first order for p, the ordering is
> field by field, i.e., all the unknowns of u are ordered first then followed
> by all the unknowns of p.
>
> For the second case, is there any way to change to a point by point
> ordering? Though in such case there is no unknown of p on the mid-edge
> point.

Try setting --node-major-dofs on the command line.  It should give you
a point by point ordering, though as you say there's no way in that
case for the number of variables to be *identical* on each point.
---
Roy