scholarly journals NODAL COSINE SINE MATERIAL INTERPOLATION IN MULTI OBJECTIVE TOPOLOGY OPTIMIZATION WITH THE GLOBAL CRITERIA METHOD FOR LINEAR ELASTO STATIC, HEAT TRANSFER, POTENTIAL FLOW AND BINARY CROSS ENTROPY SHARPENING

2021 ◽  
Vol 1 ◽  
pp. 2247-2256
Author(s):  
Martin Denk ◽  
Klemens Rother ◽  
Mario Zinßer ◽  
Christoph Petroll ◽  
Kristin Paetzold
Keyword(s):  
Heat Transfer ◽  
Topology Optimization ◽  
Potential Flow ◽  
Cross Entropy ◽  
Objective Criterion ◽  
Multi Objective ◽  
Material Interpolation ◽  
Continuous Material ◽  
Mean Compliance ◽  
Transfer Potential

AbstractTopology optimization is typically used for suitable design suggestions for objectives like mean compliance, mean temperature, or model analysis. Some modern modeling technics in topology optimization require a nodal based material interpolation. Therefore this article is referred to a continuous material interpolation in topology optimization. To cover a smooth and differentiable density field, we address trigonometric shape functions which are infinitely differentiable. Furthermore, we extend a so-known global criteria method with a sharpening function based on binary cross-entropy, so that sharper solutions results. The proposed material interpolation is applied to different applications such as heat transfer, elasto static, and potential flow. Furthermore, these different objectives are together optimized using a multi-objective criterion.

Three-Dimensional Fluid Topology Optimization and Validation of a Heat Exchanger With Turbulent Flow

2020 ◽  
Author(s):  
M. Pietropaoli ◽  
A. Gaymann ◽  
F. Montomoli
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Thermal Conductivity ◽  
Topology Optimization ◽  
Turbulent Flow ◽  
Experimental Investigations ◽  
Optimization Approach ◽  
Detached Eddy Simulation ◽  
Fluid Structure ◽  
Multi Objective

Abstract The present work shows an innovative design framework for fluid Topology Optimization (TO) able to fully exploit the flexibility offered by Additive Manufacturing (AM) in the production of fluid-structure interaction systems. We present a geometry optimization method able to automatically design complex and efficient heat exchangers, adapted to maximizing fluid-structure heat transfer while minimizing turbulent flow pressure drop. The core of the method is the in-house Fluid Topology Optimization solver extended to include conjugate heat transfer problems. The TO method consists in emulating a sedimentation process inside an empty cavity in which a fluid dynamics problem is numerically solved. A design variable, in this case impermeability, is iteratively updated across the fluid dynamics domain. This mechanism leads to the formation of internal solid structures accordingly to a Lagrangian multi-objective optimization approach, adopted to include a multi-objective function. The solution of the optimization routine is the set of solidified structures, shaping the final optimized geometry. In order to match engineering applications, real conditions are implemented: an impermeability dependent thermal conductivity is included and a smoother operator is adopted to bound numerical thermal conductivity gradients across solid and fluid regions. The optimization is performed on a 3-dimensional straight duct: on the walls the temperature is constant and a coolant turbulent flow is simulated (Re 10000) inside the duct. The solver builds structures enhancing the heat transfer level between the walls of the domain and a coolant flow, by generating counter rotating vortices and complex fluid patterns. This is consistent to solution proposed in the open literature, such as v-shaped ribs, even if the geometry generated is more complex and efficient. The solution is validated with a high fidelity numerical simulation on StarCCM+, using a Detached Eddy Simulation (DES). Validation results shows higher heat transfer efficiency compared to the results present in the literature: the average Nusselt number computed on the domain walls is about 20% higher than the value obtained through experimental investigations on v-shape ribbed ducts. It is the first time that this method is applied and validated on real working conditions.

scholarly journals Multi-objective topology optimization of pin-fin heat exchangers using spectral and finite-element methods

2021 ◽  
Author(s):  
Ali Ghasemi ◽  
Ali Elham
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Topology Optimization ◽  
Heat Exchangers ◽  
Conjugate Heat Transfer ◽  
Transfer Model ◽  
Multi Objective ◽  
Pin Fin ◽  
Flow Part ◽  
Pseudo Spectral

AbstractForced convective pin-fin heat exchangers, due to the high wet surface area per volume and the hindered thermal boundary layers, feature low thermal resistances. However, the considerable coolant pressure drop, particularly for densely packed fin arrays, imposes operational costs for pumping power supply. This paper develops a multi-objective topology optimization approach to optimize sink geometries in order to minimize thermal resistance and pressure loss, concurrently. In accordance to the pin-fin geometrical characteristics, a dedicated pseudo-3D conjugate heat transfer model is utilized, by assuming periodic flow and fin design pattern, to reasonably reduce the high cost of full-3D model optimization. For the solution of flow part, a pseudo-spectral scheme is used, which is intrinsically periodic and features a high spectral accuracy, and the finite element method for the non-periodic conjugate heat transfer model. Exact partial derivatives of the discrete solutions are obtained analytically by hand-differentiation. This task is rather convenient for the flow part, due to the simplicity of the pseudo-spectral implementation; however, the MATLAB symbolic toolbox is selectively utilized for the finite element code to ensure an error-free implementation. Finally, the sensitivities are computed directly or via a discrete adjoint method, for the flow and heat models, respectively. To examine the present approach, two approaches are used for optimization of a practical cooling task: constrained and unconstrained multi-objective formulations, where in all cases more emphasis is placed on thermal resistance minimization. A series of optimized heat sink geometries via constrained or unconstrained multi-objective optimizations are obtained to examine practical utility of the present approach. The optimized topologies demonstrated superior cooling performances at lower costs of pressure losses compared to conventional (circular) in-line and staggered fins, and confirmed the supremacy of topology over pure sizing optimization.

Multi-Objective Optimization of a Microturbine Compact Recuperator

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Diego Micheli ◽  
Valentino Pediroda ◽  
Stefano Pieri
Keyword(s):  
Heat Transfer ◽  
Three Dimensional ◽  
Numerical Procedure ◽  
Design Procedure ◽  
Domain Size ◽  
Multidisciplinary Optimization ◽  
Computational Domain ◽  
Surface Geometry ◽  
Multi Objective ◽  
Flux Boundary Conditions

An automatic approach for the multi-objective shape optimization of microgas turbine heat exchangers is presented. According to the concept of multidisciplinary optimization, the methodology integrates a CAD parametric model of the heat transfer surfaces, a three-dimensional meshing tool, and a CFD solver, all managed by a design optimization platform. The repetitive pattern of the surface geometry has been exploited to reduce the computational domain size, and the constant flux boundary conditions have been imposed to better suit the real operative conditions. A new approach that couples cold and warm fluids in a periodic unitary cell is introduced. The effectiveness of the numerical procedure was verified comparing the numerical results with available literature data. The optimization objectives are maximizing the heat transfer rate and minimizing both friction factor and heat transfer surface. The paper presents the results of the optimization of a 50kWMGT recuperator. The design procedure can be effectively extended and applied to any industrial heat exchanger application.

An Evolutionary Multi-Objective Optimization Approach to the Topology Optimization of Auxetic Structures

2002 ◽  
Author(s):  
Ashraf O. Nassef
Keyword(s):  
Topology Optimization ◽  
Elastic Modulus ◽  
Finite Elements ◽  
Multiobjective Optimization ◽  
Poisson Ratio ◽  
Optimization Approach ◽  
Multi Objective Optimization ◽  
Finite Elements Analysis ◽  
Multi Objective ◽  
Auxetic Structures

Auxetic structures are ones, which exhibit an in-plane negative Poisson ratio behavior. Such structures can be obtained by specially designed honeycombs or by specially designed composites. The design of such honeycombs and composites has been tackled using a combination of optimization and finite elements analysis. Since, there is a tradeoff between the Poisson ratio of such structures and their elastic modulus, it might not be possible to attain a desired value for both properties simultaneously. The presented work approaches the problem using evolutionary multiobjective optimization to produce several designs rather than one. The algorithm provides the designs that lie on the tradeoff frontier between both properties.

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