# Dannberg et al. \[2019\] Ridge melt migration model failing in SolverCG

**URL:** <https://community.geodynamics.org/t/dannberg-et-al-2019-ridge-melt-migration-model-failing-in-solvercg/4473>\
**Category:** ASPECT\
**Tags:** convergence\
**Created:** [February 27, 2026, 7:21am UTC](https://community.geodynamics.org/t/dannberg-et-al-2019-ridge-melt-migration-model-failing-in-solvercg/4473 "2026-02-27T07:21:03Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![gito](https://yyz2.discourse-cdn.com/flex036/user_avatar/community.geodynamics.org/gito/32/756_2.png) [@gito](https://community.geodynamics.org/u/gito)\
**Post date:** [February 27, 2026, 7:21am UTC](https://community.geodynamics.org/t/dannberg-et-al-2019-ridge-melt-migration-model-failing-in-solvercg/4473/1 "2026-02-27T07:21:03Z")

</div>

Hello,

ASPECT 3.1.0-pre is not solving timestep 0 of the Dannberg et al. [2019], mid-ocean ridge melting model. It produces solutions, but when it gets down to the last refinement level the BlockSchurPreconditioner fails. I’ve tried relaxing the Linear solver tolerance to 1e-6, and reducing the global refinement from 6 to 5, but it ends up crashing in the same solver block (in timestep 1 or 2) . I’ve attached my input file (adapted from “mid\_ocean\_ridge\_adaptive\_porosity.prm”), std out, and error output. There was no solver\_history.txt file produced. A few of the original input parameters have changed or gone away (noted by “G.Ito”) so I wonder if those contribute to the issues.

Thanks in advance,

Garrett

[input\_Lst1e-6.prm](https://community.geodynamics.org/uploads/short-url/97hQXwAt8po1DFeGslxx53JEF2J.prm) (11.3 KB)

[log\_Lst1e-6.out.txt](https://community.geodynamics.org/uploads/short-url/pQZkWdfPkcQB9n589I0l68q1T3n.txt) (9.4 KB)

[log\_Lst1e-6.err.txt](https://community.geodynamics.org/uploads/short-url/mqMTJy7tnOt91hpU9goNMfe9hKY.txt) (20.2 KB)

---

<div class="post-metadata">

**Author:** ![gito](https://yyz2.discourse-cdn.com/flex036/user_avatar/community.geodynamics.org/gito/32/756_2.png) [@gito](https://community.geodynamics.org/u/gito)\
**Post date:** [February 28, 2026, 5:28am UTC](https://community.geodynamics.org/t/dannberg-et-al-2019-ridge-melt-migration-model-failing-in-solvercg/4473/2 "2026-02-28T05:28:50Z")

</div>

Ah! The input file was trying to solve the problem with 6 and 6 or 5 and 6 Initial global and adaptive refinement levels. This looks to be beyond the limits of resolution shown in the paper, and hence what set the limit on the number of rows in Table 4. It solves fine with the resolution I surmise the problem needs in practice. Note to self: failure in the inner CGSolve is a symptom of too many dofs for the problem. Comments welcome, though.