Relax ghosting check

[dschwen]

Reason

When using patch_update_strategy=iteration with dynamic mesh changes (e.g., ElementSubdomainModifier changing element subdomains), NearestNodeLocator fails in parallel
with the error: "The nearest neighbor lies outside the ghosted set of elements."

This occurs because:

1. Subdomain changes can cause boundary nodes to appear/disappear on contact surfaces
2. Geometric search validation checks if elements are ghosted BEFORE the deferred ghosting is applied
3. In parallel, the validation tries to access processor_id() of elements that aren't yet ghosted, causing false errors

The issue is particularly problematic for problems with:

• Moving phase boundaries tracked by ElementSubdomainModifier
• Contact constraints on boundaries affected by subdomain changes
• Multi-processor simulations with iteration-based patch updates

Design

Replace overly strict ghosting validation in NearestNodeLocator::findNodes() and NearestNodeLocator::updatePatch() with a more appropriate check:

Previous validation (too strict):

• Checked if elements were in the current ghosted set (ghost) OR pending ghosting set (new_ghost)
• Attempted to query processor_id() of elements that may not be accessible yet
• Failed for elements correctly computed for ghosting but not yet applied

New validation (appropriate):

• Only validates that elements are accessible (not remote_elem or nullptr)
• Trusts that the ghosting patch computation is correct
• Defers strict validation until ghosting is actually applied by the framework

Additionally:

• Track pending ghosted elements in new_ghost set initialized from _new_ghosted_elems
• Accumulate newly computed ghosting into new_ghost for proper tracking across iterations

Impact

API Changes: None - this is an internal fix to validation logic

Behavior Changes:

• More lenient validation that allows deferred ghosting to work correctly in parallel
• Eliminates false positive errors when boundaries change dynamically
• Maintains safety by still catching truly inaccessible elements

User Impact:

• Users with patch_update_strategy=iteration and dynamic boundaries (ElementSubdomainModifier, phase field, etc.) will no longer see spurious ghosting errors in parallel
• No input file changes required
• patch_update_strategy=always users see no change (already worked)

Testing:

• Fixes parallel failures in contact problems with subdomain changes
• Serial behavior unchanged
• All existing tests should pass

[moosebuild]

Job Test, step Results summary on 0561c0c wanted to post the following:

Framework test summary

Compared against d8769bb in job civet.inl.gov/job/3367375.

Removed tests

Added tests

Run time changes

Modules test summary

Compared against d8769bb in job civet.inl.gov/job/3367375.

Removed tests

Added tests

Run time changes

[moosebuild]

Job Documentation, step Docs: sync website on 0561c0c wanted to post the following:

View the site here

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