[Libmesh-users] EquationSystems::init() takes an enormous amount of time with scalar variables

[Bailey C. <bcu...@gm...>]

Hi there,


I’m using libMesh to perform topology optimization on a mesh with a
spherical surface. I only have a single LinearImplicitSystem. The normal
displacement of nodes on the spherical surface needs to be constrained to
force the surface to remain spherical. I am using Lagrange multipliers to
do this, but have found that adding a large number of scalar variables
results in EquationSystems::init() taking an extraordinary amount of time
to build the system. For a mesh with 9585 nodes, 45728 elements, and
first-order interpolation, EquationSystems::init() takes practically no
time at all without scalar variables for the MPCs. However, when I add 1332
scalar variables (one for each node on the spherical surface,
EquationSystems::init() runs for over an hour. Is this to be expected with
libMesh? Is there a more efficient way to apply MPCs to numerous nodes?


Bailey C