Flow restrictor design for extrusion slit dies for a range of materials: Simulation and comparison of optimization techniques

Sienz, Johann; Bates, Stuart J.; Pittman, J. F. T.

doi:10.1016/j.finel.2005.06.008

Cited by 25 publications

(15 citation statements)

References 19 publications

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“…This capability is being exploited in the rapidly-growing research field of Computational Fluid Dynamics (CFD) optimization which is being utilised across a range of areas including aerospace engineering [2,3], tribology [4], polymer moulding [5], ship design [6], vehicle aerodynamics [7][8][9][10], hospital ward ventilation [11] and jet pump design [12]. Although these examples demonstrate the versatility of CFD-based optimization, there is one aspect which can prove problematic: the presence of numerical noise in the CFD responses [10,[13][14][15][16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Dealing with numerical noise in CFD-based design optimization

Gilkeson¹,

Торопов²,

Thompson³

et al. 2014

Computers & Fluids

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SUMMARYNumerical noise is an inevitable by-product of Computational Fluid Dynamics (CFD) simulations which can lead to challenges in finding optimum designs. This article draws attention to the issue, illustrating the difficulties it can cause for road vehicle aerodynamics simulations. Firstly a benchmark problem is used to assess a range of turbulence models and grid types. Large noise amplitudes up to 22% are evident for solutions computed on unstructured tetrahedral grids whereas computations on hexahedral and polyhedral grid structures exhibit substantially less noise. The Spalart Allmaras turbulence model is shown to be far less susceptible to noise levels than two other commonly-used models for this application.Secondly, multi-objective aerodynamic shape optimization is applied to a fairing for a practical road vehicle which is parameterised in terms of three design variables. Moving Least Squares (MLS) metamodels are constructed from 50 highfidelity CFD solutions for two objective functions. Subsequent optimization is successful for the first objective, however numerical noise levels in excess of 7% give rise to difficulties for the second one. A revision to the problem leads to success and the construction of a small Pareto Front. Further analysis underlines the inherent capability of MLS metamodels in dealing with noisy CFD responses.

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Section: Introductionmentioning

confidence: 99%

Dealing with numerical noise in CFD-based design optimization

Gilkeson¹,

Торопов²,

Thompson³

et al. 2014

Computers & Fluids

View full text Add to dashboard Cite

show abstract

“…Optimization of complex flows is a rapidly growing research field with several applications in aircraft aerodynamics and turbomachinery (Keane and Nair 2005;Jeong, Obayashi, and Yamamoto 2006;Shahrokhi and Jahangirian 2010) and several recent examples in, for example, polymer moulding (Sienz, Bates, and Pittman 2006), tribology (Buscaglia, Auras, and Jai 2006), jet pump design (Fan et al 2011) and hospital ward ventilation (Khan, Noakes, and Toropov 2012). The ability of CFD methods, such as those based on popular Reynolds averaged Navier-Stokes (RANS) turbulence models, to predict drag and surface pressure coefficients accurately for flow past complex vehicle geometries (Roy 2006;Roy and Ghuge 2009) has also led to increasing popularity of CFD-based optimization methods in vehicle design.…”

Section: Introductionmentioning

confidence: 99%

Multi-objective aerodynamic shape optimization of small livestock trailers

Gilkeson

Торопов

Thompson

et al. 2012

Engineering Optimization

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This article presents a formal optimization study of the design of small livestock trailers, within which the majority of animals are transported to market in the UK. The benefits of employing a headboard fairing to reduce aerodynamic drag without compromising the ventilation of the animals' microclimate are investigated using a multi-stage process involving computational fluid dynamics (CFD), optimal Latin hypercube (OLH) design of experiments (DoE) and moving least squares (MLS) metamodels. Fairings are parameterized in terms of three design variables and CFD solutions are obtained at 50 permutations of design variables. Both global and local search methods are employed to locate the global minimum from metamodels of the objective functions and a Pareto front is generated. The importance of carefully selecting an objective function is demonstrated and optimal fairing designs, offering drag reductions in excess of 5% without compromising animal ventilation, are presented.

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“…The diversity in the rheology of different polymers also needs individual optimization of the die for each polymer. The combination of polymer and die channel geometry often requires additional equipment such as a choker bar [10]. In this case, a trial‐and‐error approach can be used to obtain a uniform velocity at the die exit.…”

Section: Introductionmentioning

confidence: 99%

An optimization method with experimental validation for the design of extrusion wire coating dies for a range of different materials and operating conditions

Lebaal

Puissant²,

Schmidt

et al. 2012

Polymer Engineering & Sci

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The objective of this article is to determine a wire coating-hanger melt distributor geometry to ensure a homogenous exit velocity distribution that will best accommodate a wide material range and multiple operating conditions (i.e., die wall temperature and flow rate change). The computational approach incorporates finite element (FE) analysis to evaluate the performance of a die design and includes a nonlinear constrained optimization algorithm based on the Kriging interpolation and sequential quadratic programming algorithm to update the die geometry. Two optimization problems are then solved, and the best solution is taken into account to manufacture the optimal distributor. The Taguchi method is used to investigate the effect of the operating conditions, i.e., melt and die wall temperature, flow rate and material change, on the velocity distribution for the optimal die. In the example chosen, the wire coating die geometry is optimized by taking into account the geometrical limitations imposed by the tool geometry. Finally, the FE analysis and optimization results are validated by comparison with the experimental data obtained with the optimal die. The purpose of the experiments described below is to investigate the effect of material change.

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Flow restrictor design for extrusion slit dies for a range of materials: Simulation and comparison of optimization techniques

Cited by 25 publications

References 19 publications

Dealing with numerical noise in CFD-based design optimization

Dealing with numerical noise in CFD-based design optimization

Multi-objective aerodynamic shape optimization of small livestock trailers

An optimization method with experimental validation for the design of extrusion wire coating dies for a range of different materials and operating conditions

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