WP 2: CAD-free design parametrisation

CAD-free parametrisations are light-weight and can easily be integrated into workflows, the difficulty of returning the results to CAD will be addressed in WP3. Three major CAD-free parametrisations will be further developed in this WP:

Topology optimisation is usually based on either on a variable porosity field or the level-set method. Irrespective of how the outcome of a topology optimisation can be transformed to a CAD-based representation, a promising optimization algorithm is one that combines topology and shape optimization, applied in an interleaving way. This development is strongly linked with WP3 and also WP5 regarding the handling of geometrical constraints in topology optimisation.

Node-based optimisation offers the richest possible design space for shape optimisation, but allows oscillatory shapes which need regularisation/smoothing. Better smoothing preconditioners will be developed with cover 3-D viscous flows and a wide range of cost functions, integration with multi-level methods for the design will provide the necessary improvements in convergence to the optimum, and hence computational cost. Volume mesh morphing methods for large displacement suitable for node-based and CAD-based parametrisations will be developed using linear elasticity models, which include mesh quality improvement, mesh repair, remeshing and interpolation.

Morphing based methods allow the expression of simple box constraints, but need manual setup. Harmonic-coordinate based morphing approaches will be implemented. Adaptive methods for lattice node movement and subdivision will be developed that combine HCM with adjoint sensitivities to reduce manual input.

Objectives:

• Adaptive preconditioning and regularisation for node-based parametrisation

• Parametrisation based on Harmonic Coordinate Morphing

• Robust and efficient volume mesh smoothing allowing large deformations using linear elasticity formulations, optimisation-based smoothing and preconditioning.

• Automated deformation workflows with quality checking, efficient restarts through remeshing and interpolation

Personnel and Project Deliverables

WP leader: Queen Mary University of London - Dr. Jens-Dominik Mueller

Rejish Jesudasan (ESR 1) "Node-based parametrisation kernel"

Pavlos Alexias (ESR 4) "Harmonic co-ordinate based mesh morphing" and "Advanced control for HC"

Chris Kapellos (ESR15) "VW workflow with RBF and HC morphing"

James Koch (ESR 8) "Combined/hierarchical shape/topology optimisation"

Athanasios Liatsikouras (ESR 6) "Mesh-Morpher with adaptive CAD-free parametrisation"

Pavanakumar Mohanamuraly (ESR 3) "Robust mesh deformation library"

Marc Schwalbach (ESR 14) "Mesh deformation method linked to CAD"