Model Order Reduction by means of Active Subspaces and Dynamic Mode Decomposition for Parametric Hull Shape Design Hydrodynamics

TL;DR

This paper combines active subspaces and dynamic mode decomposition to reduce the complexity of parametric hull shape design, enabling efficient hydrodynamic simulations and sensitivity analysis in ship design.

Contribution

It introduces a novel pipeline integrating active subspaces, dynamic mode decomposition, and response surface methods for efficient parametric hull hydrodynamics analysis.

Findings

Active subspaces identify lower-dimensional structures in shape parameters.

Dynamic mode decomposition reconstructs steady states from few snapshots.

The approach reduces computational cost in ship hull design simulations.

Abstract

We present the results of the application of a parameter space reduction methodology based on active subspaces (AS) to the hull hydrodynamic design problem. Several parametric deformations of an initial hull shape are considered to assess the influence of the shape parameters on the hull wave resistance. Such problem is relevant at the preliminary stages of the ship design, when several flow simulations are carried out by the engineers to establish a certain sensibility with respect to the parameters, which might result in a high number of time consuming hydrodynamic simulations. The main idea of this work is to employ the AS to identify possible lower dimensional structures in the parameter space. The complete pipeline involves the use of free form deformation to parametrize and deform the hull shape, the high fidelity solver based on unsteady potential flow theory with fully nonlinear free surface treatment directly interfaced with CAD, the use of dynamic mode decomposition to reconstruct the final steady state given only few snapshots of the simulation, and the reduction of the parameter space by AS, and shared subspace. Response surface method is used to minimize the total drag.