Work in Progress
Adjont RANS simulations and parametric modeling have been moved closer to each other during the advancement of the FORM-PRO project. It is now possible to use the adjoint computation to directly draw conclusions for the involved form parameters in the FRIENDSHIP-Framework. But how does it work?
The result of an adjoint computation for a ship hull is a field composed of sensitivities for every grid point on the hull surface. These sensitivities tell how large the influence of the normal displacement of this point is on a specified objective (e.g. resistance or wake quality). The sensitivities can be visualized as shown in the lower middle of the picture for the wake quality and give a lead about how to change the geometry in order to improve the objective.
When working with a parametric model, the geometry is controlled by parameters. So what is needed is a way of translating the sensitivities into information about how to change the parameter values for performance improvement. As a first step to accomplish this a new geometric sensitivity analysis can be carried out in the FRIENDSHIP-Framework. Here the influence of selected parameters on the surface deformation is evaluated and can then be visualized for each parameter. The plot for one parameter is shown in the lower right of the picture.
Multiplying this field for one parameter with the sensitivity field from the adjoint computation yields a scalar parameter sensitivity that describes the influence of this parameter on the objective function. A table with parameter sensitivities for a set of geometry parameters is visible in the lower left of the picture.
This methodology gives an indication on how to alter the geometry for a better product performance with comparably very small computational effort.
Even if you don't use an adjoint RANS solver, the new geometric sensitivity analysis is still a handy tool to understand and document a parametric model. Just run it and quickly get detailed information on how every parameter influences the surface geometry.