Question about velocity mapping in DLM/ex0 example.cpp (line 551–561)

[皮卡丘卡皮卡丘]

Dear all,

I have a question regarding the data mapping section in examples/DLM/ex0/example.cpp, specifically around lines 551–585.

In this part of the code, during the step

// Map IBFE data to the FEM solver and perform half a time step with the structural solver.
{
    System& ibfe_x_system =
        ibfe_beam_equation_systems->get_system(ib_method_ops->getCurrentCoordinatesSystemName());
    *fem_y_system.solution = *ibfe_x_system.solution;
    *fem_y_system.current_local_solution = *ibfe_x_system.current_local_solution;

    System& ibfe_u_system = fem_equation_systems->get_system(fem_solver->getVelocitySystemName());
    *fem_v_system.solution = *ibfe_u_system.solution;
    *fem_v_system.current_local_solution = *ibfe_v_system.current_local_solution;
}

I noticed that the velocity system (ibfe_u_system) is being retrieved from
fem_equation_systems rather than from ibfe_beam_equation_systems.

Could you please clarify the intended logic here?
Is this line intentionally using the FEM velocity system (e.g., for synchronization within the FEM solver),
or is it possibly a typo and should instead access
ibfe_beam_equation_systems->get_system(ib_method_ops->getVelocitySystemName())
to be symmetric with the later mapping step (FEM → IBFE)?

Thank you very much for your time and for maintaining such a great codebase.

Best regards,
Peng

[皮卡丘卡皮卡丘]

And I have a question about the last line:
Why is current_local_solution copied from ibfe_v_system, rather than from ibfe_u_system?
Shouldn’t it be consistent with the first line (i.e., both solution and current_local_solution copied from the same system)?
Is there a specific reason for this design, or could it be a small typo in the example code?
Thank you in advance for the clarification!