Topology optimisation for fluid flow and heat transfer applications

In this study, we apply the two most prevalent topological optimisation algorithms to the design of single material heat sinks and heat exchangers. We aim to determine the merits and drawbacks of each method, extend the most suitable method to consider multi-material structures and to subsequently apply this method to design heat recovery structures subject to fluid convection. The two optimisation methods assessed were the density method and the level-set topological optimisation method. This study presents a review of the current state-of-the-art in topology optimisation, identifying gaps and limitations in current knowledge relating to the application of these methods to fluid-flow and heat transfer problems. Both topological optimisation approaches have been implemented in a numerical framework consisting of a combination of the Matlab package and the Comsol Multiphysics package. The optimisation algorithms have been implemented in Matlab while Comsol is used to perform thermofluid analyses. The implementation has been validated against standard test cases. Comparison of the two methods indicated that the level-set method developed designs performed better than those developed by the density method, and that the level-set method had a number of additional advantages stemming from its superior handling of fluid-solid interface boundary. The relative performance of the approaches is fully discussed. The level-set approach was extended through implementation of a regular re-initialisation capability to increase the accuracy of interface boundary and through implementation of an adjoint-based sensitivity evaluation to enhance the computational efficiency. This framework is applied to the design of heat-recovery channels, particularly assessing the effect of solid-to-fluid thermal conductivity ratio and flow Reynolds number on the optimised shapes. This framework is subsequently extended to consider multi-material problems through development of the underlying level-set formulation. The optimal design of copper-aluminium and copper-steel heatsinks are assessed and results and observations are discussed. Potential areas for further works are discussed after drawing conclusions.

Name dc:type.qualificationname

phd

Level dc:type.qualificationlevel

doctoral

Grantor dc:publisher.institution

University of Greenwich

Year dc:date.issued

2018

Author dc:creator

• Santhanakrishnan, Mani Sekaran

Advisors dc:contributor.advisor

• Tilford, Timothy
• Bailey, Christopher

• QA Mathematics

Language dc:language

en