2 research outputs found
A coupled discrete adjoint method for optimal design with dynamic non-linear fluid structure interactions
Incorporating high-fidelity analysis methods in multidisciplinary design optimization necessitates efficient sensitivity evaluation, which is particularly important for time-accurate problems. This thesis presents a new discrete adjoint formulation suitable for fully coupled, non-linear, dynamic FSI problems. The solution includes time-dependent adjoint variables that arise from grid motion and chosen time integration methods for both the fluid and structural domains. Implemented as a generic multizone discrete adjoint solver for time-accurate analysis in the open-source multiphysics solver SU2, this provides a flexible framework for a wide range of applications. Design optimization of aerodynamic structures need accurate characterization of the coupled
fluid-structure interactions (FSI). Incorporating high-fidelity analysis methods in the multidisciplinary design optimization (MDO) necessitates efficient sensitivity evaluation, which is
particularly important for time-accurate problems. Adjoint methods are well established for
sensitivity analysis when large number of design variables are needed. The use of discrete adjoint method through algorithmic differentiation enables the evaluation of sensitivities using
an approximation of the Jacobian of the coupled problem, thus enabling this approach to be
applied for multidisciplinary analysis.
This thesis presents a new discrete adjoint formulation suitable for fully coupled, non-linear,
dynamic FSI problems. A partitioned approach is considered with finite volume for the fluid
and finite elements for the solid domains. The solution includes the time-dependent adjoint
variables that arise from the grid motion and chosen time integration methods for both the fluid
and structural domains. Implemented as a generic multizone discrete adjoint solver for timeaccurate analysis in the open-source multiphysics solver SU2, this provides a flexible framework
for a wide range of applications. The partitioned FSI solver approach has been leveraged to
extend the dynamic FSI capabilities to low speed flows through the introduction of a densitybased unsteady incompressible flow solver.
The developed methodology and implementation are demonstrated using a range of numerical
test cases. Optimal design for steady, coupled FSI problems are firstly presented before moving
to the building blocks of dynamic coupled problems using single domain analysis, for both
structural and fluid domains in turn. The new unsteady incompressible fluid solver, for both
the primal and adjoint analysis, are verified against a range of well-known benchmark test
cases, including problems with grid motion. Finally, applications of coupled dynamic problems
are presented to verify both the unsteady incompressible solver for FSI as well as the successful
verification of the discrete adjoint sensitivities for the transient response of a transonic compliant
airfoil for a variety of both aerodynamic and structural objective functions.Open Acces