scholarly journals Data-Efficient Design Exploration through Surrogate-Assisted Illumination

2018 ◽  
Vol 26 (3) ◽  
pp. 381-410 ◽  
Author(s):  
Adam Gaier ◽  
Alexander Asteroth ◽  
Jean-Baptiste Mouret
Keyword(s):  
Three Dimensional ◽  
Flow Simulation ◽  
Optimal Solution ◽  
Optimization Techniques ◽  
Efficient Design ◽  
Design Exploration ◽  
High Performing ◽  
Airfoil Optimization ◽  
Modeling Techniques ◽  
Illumination Algorithms

Design optimization techniques are often used at the beginning of the design process to explore the space of possible designs. In these domains illumination algorithms, such as MAP-Elites, are promising alternatives to classic optimization algorithms because they produce diverse, high-quality solutions in a single run, instead of only a single near-optimal solution. Unfortunately, these algorithms currently require a large number of function evaluations, limiting their applicability. In this article, we introduce a new illumination algorithm, Surrogate-Assisted Illumination (SAIL), that leverages surrogate modeling techniques to create a map of the design space according to user-defined features while minimizing the number of fitness evaluations. On a two-dimensional airfoil optimization problem, SAIL produces hundreds of diverse but high-performing designs with several orders of magnitude fewer evaluations than MAP-Elites or CMA-ES. We demonstrate that SAIL is also capable of producing maps of high-performing designs in realistic three-dimensional aerodynamic tasks with an accurate flow simulation. Data-efficient design exploration with SAIL can help designers understand what is possible, beyond what is optimal, by considering more than pure objective-based optimization.

An Adjoint Formulation for Shape Optimization in Free-Surface Potential Flow

2001 ◽  
Vol 45 (04) ◽  
pp. 269-278
Author(s):  
Saad A. Ragab
Keyword(s):  
Free Surface ◽  
Shape Optimization ◽  
Three Dimensional ◽  
Optimal Solution ◽  
Free Surface Flow ◽  
Surface Flow ◽  
Optimization Techniques ◽  
Marine Vehicles ◽  
Direct Calculations

This paper is a step towards the application of automatic shape optimization techniques to the hydrodynamic design of marine vehicles. The flow is assumed to be irrotational and free-surface conditions are linearized. Several objective functionals of relevance to free-surface flow are proposed, and adjoint formulations for the determination of their gradients are derived. The accuracy of the gradient using the adjoint formulations has been verified by comparisons with direct calculations using second-order finite differences. The method is then used to obtain an optimal solution to the inverse problem for a three-dimensional body submerged near a free surface, and to design a minimum wave resistance body.

Parametric modelling of helical rotors for efficient design of twin-screw superchargers

2007 ◽  
Vol 221 (2) ◽  
pp. 267-272 ◽  
Author(s):  
K Ilie ◽  
A Subic
Keyword(s):  
Performance Optimization ◽  
Computer Aided Design ◽  
Geometric Model ◽  
Three Dimensional ◽  
Flow Simulation ◽  
Parametric Modelling ◽  
Efficient Design ◽  
Rotor Profile ◽  
Twin Screw ◽  
Aided Design

The parametric three-dimensional geometric model of twin-screw supercharger rotors of any aspect ratio was developed. For model validation through visualization, computer-aided design (CAD) rotor models with scalable data were generated in commercial CAD software and calibrated experimentally by laser Doppler velocimetry (LDV) tests. Calibrated rotor profile data can be transferred into CAD-CFD interface for flow simulation for performance optimization.

scholarly journals Effects of 3D Printing-Line Directions for Stretchable Sensor Performances

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1791
Author(s):  
Chi Cuong Vu ◽  
Thanh Tai Nguyen ◽  
Sangun Kim ◽  
Jooyong Kim
Keyword(s):  
3D Printing ◽  
Thermoplastic Polyurethane ◽  
Three Dimensional ◽  
Optimal Solution ◽  
Human Motion ◽  
Repeated Measurements ◽  
Fused Filament Fabrication ◽  
And Performance ◽  
The Times ◽  
Stretchable Sensors

Health monitoring sensors that are attached to clothing are a new trend of the times, especially stretchable sensors for human motion measurements or biological markers. However, price, durability, and performance always are major problems to be addressed and three-dimensional (3D) printing combined with conductive flexible materials (thermoplastic polyurethane) can be an optimal solution. Herein, we evaluate the effects of 3D printing-line directions (45°, 90°, 180°) on the sensor performances. Using fused filament fabrication (FDM) technology, the sensors are created with different print styles for specific purposes. We also discuss some main issues of the stretch sensors from Carbon Nanotube/Thermoplastic Polyurethane (CNT/TPU) and FDM. Our sensor achieves outstanding stability (10,000 cycles) and reliability, which are verified through repeated measurements. Its capability is demonstrated in a real application when detecting finger motion by a sensor-integrated into gloves. This paper is expected to bring contribution to the development of flexible conductive materials—based on 3D printing.

Assessment of Unsteady Flows in Turbines

1992 ◽  
Vol 114 (1) ◽  
pp. 79-90 ◽  
Author(s):  
O. P. Sharma ◽  
G. F. Pickett ◽  
R. H. Ni
Keyword(s):  
Unsteady Flow ◽  
Three Dimensional ◽  
Flow Simulation ◽  
Experimental Investigations ◽  
Flow Parameters ◽  
Research Activities ◽  
Flow Features ◽  
Computational Fluid Dynamics Cfd ◽  
Turbine Design ◽  
The Impact

The impacts of unsteady flow research activities on flow simulation methods used in the turbine design process are assessed. Results from experimental investigations that identify the impact of periodic unsteadiness on the time-averaged flows in turbines and results from numerical simulations obtained by using three-dimensional unsteady Computational Fluid Dynamics (CFD) codes indicate that some of the unsteady flow features can be fairly accurately predicted. Flow parameters that can be modeled with existing steady CFD codes are distinguished from those that require unsteady codes.

scholarly journals A Three-Dimensional Simulation of Particle Distribution in a Separator and Structure Optimization with the Statistical Approach of Taguchi Method

2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
Jinjin Liu ◽  
Kai Liu ◽  
Tong Zhao ◽  
Zhuofei Xu
Keyword(s):  
Taguchi Method ◽  
Three Dimensional ◽  
Optimal Solution ◽  
Structure Design ◽  
Dust Particles ◽  
Surface Element ◽  
Phase Method ◽  
Discrete Phase ◽  
Distribution Uniformity ◽  
Dimensional Simulation

A three-dimensional numerical simulation combining discrete phase method (DPM) and porous media based on the theory of Euler-Lagrange has been employed to investigate particles distribution in a separator. The DPM model is applied to monitor the movement of individual particles and calculate the contact force between them in the separator. The simulation results display the migration feature of dust particles over time and the distribution of particles on the surface element in porous region and reveal that the flow field influences the distribution uniformity of the particles in porous area directly. Based on the analysis, the structure of separator is optimized by the Taguchi method. An orthogonal relation motion has been established. The optimal solution is achieved by the calculation of the weight relationship. The calculated optimal structure is evaluated by the signal to noise (SNR). The result reveals that the values of SNR in case are eligible. As a result, the research of the separator points out a useful and improvable method for the parameter optimization of structure design.

Computation of Flow Through a Three-Dimensional Periodic Array of Porous Structures by a Parallel Immersed-Boundary Method

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
Zhenglun Alan Wei ◽  
Zhongquan Charlie Zheng ◽  
Xiaofan Yang
Keyword(s):  
Porous Media ◽  
Parallel Implementation ◽  
Flow Behavior ◽  
Three Dimensional ◽  
Flow Simulation ◽  
Periodic Array ◽  
Immersed Boundary ◽  
Navier Stokes Equation ◽  
Flow Through ◽  
Ib Method

A parallel implementation of an immersed-boundary (IB) method is presented for low Reynolds number flow simulations in a representative elementary volume (REV) of porous media that are composed of a periodic array of regularly arranged structures. The material of the structure in the REV can be solid (impermeable) or microporous (permeable). Flows both outside and inside the microporous media are computed simultaneously by using an IB method to solve a combination of the Navier–Stokes equation (outside the microporous medium) and the Zwikker–Kosten equation (inside the microporous medium). The numerical simulation is firstly validated using flow through the REVs of impermeable structures, including square rods, circular rods, cubes, and spheres. The resultant pressure gradient over the REVs is compared with analytical solutions of the Ergun equation or Darcy–Forchheimer law. The good agreements demonstrate the validity of the numerical method to simulate the macroscopic flow behavior in porous media. In addition, with the assistance of a scientific parallel computational library, PETSc, good parallel performances are achieved. Finally, the IB method is extended to simulate species transport by coupling with the REV flow simulation. The species sorption behaviors in an REV with impermeable/solid and permeable/microporous materials are then studied.

scholarly journals Development of a Three-Dimensional Geometry Optimization Method for Turbomachinery Applications

2004 ◽  
Vol 10 (5) ◽  
pp. 373-385
Author(s):  
Steffen Kämmerer ◽  
Jürgen F. Mayer ◽  
Heinz Stetter ◽  
Meinhard Paffrath ◽  
Utz Wever ◽  
...  
Keyword(s):  
Optimization Problem ◽  
Stokes Equations ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Optimization Techniques ◽  
Navier Stokes ◽  
Physical Parameters ◽  
Flow Solver ◽  
Flow Simulations ◽  
Sensitivity Equations

This article describes the development of a method for optimization of the geometry of three-dimensional turbine blades within a stage configuration. The method is based on flow simulations and gradient-based optimization techniques. This approach uses the fully parameterized blade geometry as variables for the optimization problem. Physical parameters such as stagger angle, stacking line, and chord length are part of the model. Constraints guarantee the requirements for cooling, casting, and machining of the blades.The fluid physics of the turbomachine and hence the objective function of the optimization problem are calculated by means of a three-dimensional Navier-Stokes solver especially designed for turbomachinery applications. The gradients required for the optimization algorithm are computed by numerically solving the sensitivity equations. Therefore, the explicitly differentiated Navier-Stokes equations are incorporated into the numerical method of the flow solver, enabling the computation of the sensitivity equations with the same numerical scheme as used for the flow field solution.This article introduces the components of the fully automated optimization loop and their interactions. Furthermore, the sensitivity equation method is discussed and several aspects of the implementation into a flow solver are presented. Flow simulations and sensitivity calculations are presented for different test cases and parameters. The validation of the computed sensitivities is performed by means of finite differences.

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