How to restrict a NodalDamper (BoundingValueNodalDamper) to specific blocks?

[PengWei97]

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Question

Dear MOOSE team,

I have a mesh with two touching blocks:

• Block 1: electrode – variable theta_m is defined here
• Block 2: electrolyte – theta_m is not defined here

I want to use:

[Dampers]
  [./limit_theta_m]
    type         = BoundingValueNodalDamper
    variable     = theta_m
    min_value    = 0.0
    max_value    = 1.0
  [../]
[]

to keep theta_m within physical bounds during nonlinear iterations.

---

🔴 Problem

If I enable the damper, the simulation crashes with a segmentation fault:

Time Step 1, time = 0.1, dt = 0.1
 0 Nonlinear |R| = 6.318228e-06
      0 Linear |R| = 6.318228e-06
      1 Linear |R| = 1.528764e-06
      2 Linear |R| = 7.777395e-07
      3 Linear |R| = 1.998457e-07
      4 Linear |R| = 4.241091e-08
      5 Linear |R| = 1.056099e-08
      6 Linear |R| = 2.925392e-09
      7 Linear |R| = 5.487313e-10

===================================================================================
=   BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES
=   PID 2525542 RUNNING AT pwmoose-PowerEdge-T640
=   EXIT CODE: 9
=   CLEANING UP REMAINING PROCESSES
=   YOU CAN IGNORE THE BELOW CLEANUP MESSAGES
===================================================================================
YOUR APPLICATION TERMINATED WITH THE EXIT STRING: Segmentation fault (signal 11)
This typically refers to a problem with your application.
Please see the FAQ page for debugging suggestions

I believe this happens because:

• BoundingValueNodalDamper evaluates nodal increments on all nodes,
• but nodes in Block 2 do not own DOFs for theta_m,
• so the damper accesses invalid memory.

When I try:

block = 'electrode'

the parser reports:

ERROR: unused parameter 'Dampers/limit_theta_m/block'

so the standard damper apparently does not support block restriction.

---

❓ My questions

1. Is there a recommended way to apply a NodalDamper only on nodes belonging to a specific block?
   (i.e., only where the variable actually exists)

2. or should I implement a custom damper derived from BoundingValueNodalDamper?

---

🙏 Any suggestions or guidance would be greatly appreciated.

Best regards,
Wei Peng

[GiudGiud]

Hello

This not implemented.
I think you cannot implement it manually in a derived class because in the threaded loop ComputeNodalDampingThread we have:

  const auto & ndampers = _nl.getNodalDamperWarehouse().getActiveObjects(_tid);
  for (const auto & damper : ndampers)
    damped_vars.insert(damper->getVariable());

  _nl.reinitIncrementAtNodeForDampers(_tid, damped_vars);

and that will always segfault when used outside of the domain of definition of the damped variable.

This would need to be modified