The continuous adjoint method for the design of hydraulic turbomachines

Papoutsis‐Kiachagias, Evangelos M.; Kyriacou, Stylianos; Giannakoglou, Kyriakos C.

doi:10.1016/j.cma.2014.05.018

Cited by 21 publications

(14 citation statements)

References 23 publications

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“…Row 2 Optimization of a Francis runner blade for cavitation suppression. Pressure distribution over the initial blading (left); areas within the white isolines are considered to be cavitated; surface deformation magnitude over the optimized blading (right), after eliminating cavitation; from [29]. Row 3 Topology optimization of an air-conditioning duct, used in a passenger car, targeting minimum total pressure losses.…”

Section: Industrial Applicationsmentioning

confidence: 99%

“…The first case deals with the blade optimization of a 3D peripheral compressor cascade in which the objective is the minimization of entropy losses within the flow passage, [28]. The second case is concerned with the shape optimization of a Francis turbine runner targeting cavitation suppression, [29], the third one with an air-conditioning duct targeting minimum total pressure losses and the last one with the shape optimization of a Volkswagen concept car, targeting minimum drag force, [30]. More comments can be found in the caption [31].…”

Section: Industrial Applicationsmentioning

confidence: 99%

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Aerodynamic Shape Optimization Using “Turbulent” Adjoint And Robust Design in Fluid Mechanics

Giannakoglou

Papadimitriou

Papoutsis‐Kiachagias

et al. 2015

Computational Methods in Applied Sciences

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This article presents adjoint methods for the computation of the firstand higher-order derivatives of objective functions F used in optimization problems governed by the Navier-Stokes equations in aero/hydrodynamics. The first part of the chapter summarizes developments and findings related to the application of the continuous adjoint method to turbulence models, such as the Spalart-Allmaras and k-ε ones, in either their low-or high-Reynolds number (with wall functions) variants. Differentiating the turbulence model, over and above to the differentiation of the mean-flow equations, leads to the computation of the exact gradient of F, by overcoming the frequently made assumption of neglecting turbulence variations. The second part deals with higher-order sensitivity analysis based on the combined use of the adjoint approach and the direct differentiation of the governing PDEs. In robust design problems, the so-called second-moment approach requires the computation of second-order derivatives of F with respect to (w.r.t.) the environmental or uncertain variables; in addition, any gradient-based optimization algorithm requires third-order mixed derivatives w.r.t. both the environmental and design variables; various ways to compute them are discussed and the most efficient is adopted. The equivalence of the continuous and discrete adjoint for this type of computations is demonstrated. In the last part, some other relevant recent achievements regarding the adjoint approach are discussed. Finally, using the aforementioned adjoint methods, industrial geometries are optimized. The application domain includes both incompressible or compressible fluid flow applications.

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Section: Industrial Applicationsmentioning

confidence: 99%

Section: Industrial Applicationsmentioning

confidence: 99%

Aerodynamic Shape Optimization Using “Turbulent” Adjoint And Robust Design in Fluid Mechanics

Giannakoglou

Papadimitriou

Papoutsis‐Kiachagias

et al. 2015

Computational Methods in Applied Sciences

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“…In the work of [11], a continuous adjoint method is developed for the design optimization of a cavitating hydrofoil based on a homogeneous multiphase mixture model. The continuous adjoint method is also employed in the work of [12] for the shape optimization of hydraulic turbomachines, with objective functions targeting various aspects of design improvements. However, applications of the continuous adjoint method for cavitation problems are not limited to CFD solvers.…”

Section: Introductionmentioning

confidence: 99%

An Adjoint Optimization Prediction Method for Partially Cavitating Hydrofoils

Anevlavi

Belibassakis

2021

JMSE

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Much work has been done over the past years to obtain a better understanding, predict and alleviate the effects of cavitation on the performance of lifting surfaces for hydrokinetic turbines and marine propellers. Lifting-surface sheet cavitation, when addressed as a free-streamline problem, can be predicted up to a desirable degree of accuracy using numerical methods under the assumptions of ideal flow. Typically, a potential solver is used in conjunction with geometric criteria to determine the cavity shape, while an iterative scheme ensures that all boundary conditions are satisfied. In this work, we propose a new prediction model for the case of partially cavitating hydrofoils in a steady flow that treats the free-streamline problem as an inverse problem. The objective function is based on the assumption that on the cavity boundary, the pressure remains constant and is evaluated at each optimization cycle using a source-vorticity BEM solver. The attached cavity is parametrized using B-splines, and the control points are included in the design variables along with the cavitation number. The sensitivities required for the gradient-based optimization are derived using the continuous adjoint method. The proposed numerical scheme is compared against other methods for the NACA 16-series hydrofoils and is found to predict well both the cavity shape and cavitation number for a given cavity length.

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“…In this work we focus on adjoint based optimal control approach which is very popular in industrial applications where Computational Fluid Dynamics simulations should be performed [19,20,21,22,23]. Moreover this method has a solid mathematical background and the existence of local optimal solutions can be investigated in many interesting cases, see for examples [21,22,24].…”

Section: Introductionmentioning

confidence: 99%

Adjoint Optimal Control Problems for Fluid-Structure Interaction Systems

Cerroni¹,

Davià²,

Manservisi³

et al. 2016

Proceedings of the VII European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS Congress 2016)

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Abstract. In the last years adjoint optimal control has been increasingly used for design and simulations in several research fields. Applications to Computational Fluid Dynamics problems dedicated to the study of transient-diffusion equations, shape optimization problems, fluid-solid conjugate heat transfer and turbulent flows can be found in literature. The study of FluidStructure Interaction problems gained popularity recently because of many interesting applications in engineering and biomedical fields. In this paper we study adjoint optimal control problems for Fluid-Structure Interaction systems in order to improve the advantages of using FSI simulations when designing engineering devices where fluid-dynamical interactions between a fluid and a solid play a significant role. We assess distributed optimal control problems with the purpose to control the fluid behavior by moving the solid region to obtain a desired fluid velocity in specific parts of the domain. The adjoint equations of the FSI monolithic system are derived and the optimality system solved for some simple cases with an in-house finite element code with mesh-moving capabilities for the study of large displacements in the solid. The approach presented in this work is general and can be used to assess different objectives and types of control in future works.

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The continuous adjoint method for the design of hydraulic turbomachines

Cited by 21 publications

References 23 publications

Aerodynamic Shape Optimization Using “Turbulent” Adjoint And Robust Design in Fluid Mechanics

Aerodynamic Shape Optimization Using “Turbulent” Adjoint And Robust Design in Fluid Mechanics

An Adjoint Optimization Prediction Method for Partially Cavitating Hydrofoils

Adjoint Optimal Control Problems for Fluid-Structure Interaction Systems

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