Multiapp steady coupled : re-solve mainapp.

[xieeeect]

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Question

I intend to realize the steady-state coupling of two physical fields u and v through multiapp. The problem is as follows:
Here I use FullSolveMultiApp, where u is mainapp and v is subapp for solving, but I do not know how to achieve the re-solving of u and end the iteration.
Thank you very much for your answers.

[GiudGiud]

Hello

To trigger multiapp fixed point iterations you have to set in the executioner block the fixed_point_max_its parameter

[maxnezdyur]

@GiudGiud Do you mean fixed_point_min_its to force more iterations then needed for convergence?

[GiudGiud]

The trigger for FP iterations is one of these two parameters.

It s on my todo list to trigger on all of them

[xieeeect]

Thank you for your answers.
I tried again yesterday and probably got it
Here's what I tried.
First, I use the FullSolveMultiApp, u for mainapp, v for subapp, use steady executioner, execute on = timestep_end. The calculation result shows that v is calculated after u is completed.
But what I want is that the program can then update some parameter from v, and then repeatedly compute u and v until the ending condition is satisfied.
I then tried to the cases of execute_on = LINEAR or NONLINEAR, but the convergence was not good.
So, I tried changing the u executioner to be Transient, giving it a large num steps, but setting steady_state_detection = true, and execute_on = 'timestep_end'.
Here, for each time step, u and v will be fully calculated and the parameters will be updated. When satisfies nl_abs_tol, the Transient calculation will be ended, and the calculation speed is also good.
Next, I will try to implement FP-iterations to solve the problem and have a comparison.
Thank you again. Have a nice day.

[maxnezdyur]

How are you sure that this is not what is going on?
The default execution of FullSolveMultiapp is TIMESTEP_BEGIN so that means if the "u" is the main app and "v" is the sub app, the order of operations is to first run and solve "v" then finish solving "u".