Performance assessment of density and level-set topology optimisation methods for 3D heatsink design

In this paper, two most prevalent topological optimisation approaches namely Density and Level set method are applied to a three dimensional heatsink design problem. The relative performance of the two approaches are compared in terms of design quality, robustness and computational speed. The work is original as for the first time it demonstrates the relative advantages and disadvantages for each method when applied to a practical engineering problem. It is additionally novel in that it presents the design of a convectively cooled heatsink by solving full thermo-fluid equations for two different solid-fluid material sets. Further, results are validated using a separate CFD study with the optimised designs are compared against a standard pin-fin based heatsink design. The results show that the Density method demonstrates better performance in terms of robustness and computational speed, while Level-set method yields a better quality design

Heat transfer characteristics of plate fin heat sink with longitudinal vortex generators

Purpose This study aims to provide an insight into the relationship between design parameters and thermal performance of plate fin heat sinks (PFHSs) incorporating longitudinal vortex generators (VGs) inside a PFHS channel. Design/methodology/approach A computational fluid dynamics model of a delta winglet pair VG mounted inside a PFHS geometry is detailed, and the model is validated by comparison with experimental data. The validated model is used to perform a virtual design of experiments study of the heat sink with bottom plate and vertical plate mounted VGs. Data from this study is used to regress a response surface enabling the influence of each of the assessed design variables on thermal performance and flow resistance to be determined. Findings The results of this study show that the thermal hydraulic performances of a PFHS with bottom plate mounted VG and vertical plate fin mounted VG are, respectively, 1.12 and 1.17 times higher than the baseline PFHS. Further, the performance variation of the heat sink with VG, relative to delta winglet’s arrangement (common flow up and common flow down), trailing edge gap length and Reynolds number were also evaluated and reported. Originality/value For the first time, performance characteristics of delta winglet VGs mounted inside the PFHS are evaluated against different design variables and a polynomial regression model is developed. The developed regression model and computed results can be used to design high performance PFHSs mounted with delta winglet VGs

Multi-material heatsink design using level-set topology optimization

In this article we apply a Level-set topological optimization algorithm to the design of multi-material heat sinks suitable for electronics thermal management. This approach is intended to exploit the potential of metal powder additive manufacturing technologies which enable fabrication of complex designs. The article details the state-of-the-art in topological optimization before defining a numerical framework for optimization of two-material and three-material based heatsink designs. The modelling framework is then applied to design a pure copper and a copper-aluminum heatsink for a simplified electronics cooling scenario and the performance of these designs are compared. The benefits and drawbacks of the implemented approach are discussed along with enhancements that could be integrated within the framework. A benchmarking study is also detailed which compares the performance of topologically optimized heat sink against a conventional pin-fin heat sink. This is the first time that topological optimization methods have been assessed for multi-material heat sink design where both conduction and convection are included in the analysis. Hence, the reported work is novel in its application of a state-of-the-art Level-set topology optimization algorithm to design multi-material structures subject to forced convective cooling. This paper is intended to demonstrate the applicability of topological optimization to the design of multi-material heatsinks fabricated using additive manufacturing processes and succeeds in this objective. The paper also discusses challenges, which need to be addressed in order to progress this modelling as a design approach for practical engineering situations. The presented methodology is able to design thermal management structures from a combination of aluminum and copper that perform similarly to pure copper but utilizing less expensive materials resulting in a cost benefit for electronics manufacturers

Effect of multiple pairs of vortex generators on the thermal performance of plate fin heat sink

In this paper, the heat transfer characteristics of multiple pairs of vortex generators (VG) mounted on vertical plate fins of plate fin heat sink (PFHS) are evaluated using computational fluid dynamic simulations. The delta winglet pairs are used as longitudinal VGs, and they are mounted one after the other in the axial direction. Critical design parameters for the double pair of VGs (DPVGs) are identified, and a design of experiment-based simulations is carried out to develop a response surface model for Nusselt number and thermal hydraulic performance parameter. Results show winglet length is a critical design parameter compared with winglet height, and the axial inter VG distance between VG pairs plays a crucial role in improving the heat transfer characteristics. The optimum inter VG distance for a double pair of VG is evaluated, and it is 2.2 to 3 times the length of the delta-winglet. Thermal hydraulic performance of PFHS with double pair of VG is 1.49 times higher than that of plain PFHS. Finally, the variation of heat transfer characteristics against velocity is also evaluated for the PFHS with a DPVG

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

Heat transfer characteristics of plate fin heat sink with longitudinal vortex generators

Purpose: This article aims to provide an insight into the relationship between design parameters and thermal performance of plate-fin heat sinks incorporating longitudinal vortex generators inside a plate fin heat sink channel. Design/Methodology/Approach: A computational fluid dynamics model of a delta winglet pair vortex generator mounted inside a plate-fin heat sink geometry is detailed, and the model is validated by comparison with experimental data. The validated model is used to perform a virtual design of experiments study of the heatsink with bottom plate and vertical plate mounted vortex generators. Data from this study is used to regress a response surface enabling the influence of each of the assessed design variables on thermal performance and flow resistance to be determined. Findings: The results show that the thermal hydraulic performance of a plate fin heat sink with bottom plate mounted vortex generator and vertical plate fin mounted vortex generator are respectively 1.12 and 1.17 times higher than the baseline plate fin heat sink. Further the performance variation of the heat sink with vortex generator, relative to delta winglet’s arrangement (common flow up and common flow down), trailing edge gap length and Reynolds number were also evaluated and reported. Originality/Value: For the first time, performance characteristics of delta winglet vortex generators mounted inside the plate fin heat sink is evaluated against different design variables and a polynomial regression model is developed. The developed regression model and computed results can be used to design high performance plate fin heat sinks mounted with delta winglet vortex generators