GridapODEs - Changes in the LinearStageOperator Struct

[shreyas02]

Hi all,

I am working on implementing strong form coupling for linear transient fluid-structure interaction problems. For that, I need to modify the linear system before solving the matrix for each time step. I want to implement this with as few changes in the Gridap library as possible. We need previous time step data and some ODE-specific data for these modifications.

The solution we arrived at was creating a CustomSolver wrapper (solve, solve!, symbolicsetup, numericalsetup) and performing all the matrix modifications in the custom numericalsetup function. The problem arises when transferring previous time-step data from the ode solver to the numerical setup function while solving a linear problem.

Solution -

The solution we arrived at was modifying the LinearStageOperator struct to include ws and usx. The struct definition for the NonlinearStageOperator contains usx and ws.

I will link the code snippets below -

Linear Stage Operator -

Gridap.jl/src/ODEs/StageOperators.jl

Lines 88 to 92 in ea403aa

	struct LinearStageOperator <: StageOperator
	J::AbstractMatrix
	r::AbstractVector
	reuse::Bool
	end

Non-Linear Stage Operator -

Gridap.jl/src/ODEs/StageOperators.jl

Lines 29 to 35 in ea403aa

	struct NonlinearStageOperator <: StageOperator
	odeop::ODEOperator
	odeopcache
	tx::Real
	usx::Function
	ws::Tuple{Vararg{Real}}
	end

Can this change be introduced in Gridap? This will make it possible to perform strong coupling for linear transient multiphysics problems. If this solution is not feasible, I would be happy to discuss alternatives.

Thanks,
Shreyas

[JordiManyer]

@AlexandreMagueresse any thoughts?