Unstructured moving grids for implicit calculation of unsteady compressible viscous flows

Jahangirian, A.; Hadidoolabi, M.

doi:10.1002/fld.877

Cited by 33 publications

(38 citation statements)

References 6 publications

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“…Since most of the computational time in such an optimization problem is consumed by the CFD solver, it must have a high e ciency and convergence rate. In order to achieve this goal, a dual-time implicit method proposed by Jahangirian and Hadidolabi [18] is used for unstructured grids.…”

Section: Numerical Ow Solvermentioning

confidence: 99%

An Optimum Neural Network for Evolutionary Aerodynamic Shape Design

2017

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Abstract. Two new techniques are proposed to enhance the estimation abilities of the conventional Neural Network (NN) method in its application to the tness function estimation of aerodynamic shape optimization with the Genetic Algorithm (GA). The rst technique is pre-processing the training data in order to increase the training accuracy of the Multi-Layer Perceptron (MLP) approach. The second technique is a new structure for the network to improve its quality through a modi ed growing and pruning method. Using the proposed techniques, one can obtain the best estimations from the NN with less computational time. The new methods are applied for optimum design of a transonic airfoil and the results are compared with those obtained from the accurate Computational Fluid Dynamics (CFD) tness evaluator and with the conventional MLP NN approach. The numerical experiments show that using the new method can reduce the computational time signi cantly while achieving improved accuracy.

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Section: Numerical Ow Solvermentioning

confidence: 99%

An Optimum Neural Network for Evolutionary Aerodynamic Shape Design

2017

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“…By applying a fully implicit time method, the flow Eq. (14) is integrated in time as follows (Jahangirian and Hadidoolabi, 2005):…”

Section: Implicit Time Integrationmentioning

confidence: 99%

“…A second order accurate time discretization is used in the present study (Hashemi and Jahangirian 2011;Jahangirian and Hadidoolabi 2005). So, the Eq.…”

Section: Implicit Time Integrationmentioning

confidence: 99%

Unsteady Compressible Flow Calculations with Least-Square Mesh-less Method

Sattarzadeh¹,

Jahangirian

Hashemi³

2016

JAFM

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A dual-time implicit mesh-less method is presented for unsteady compressible flow calculations. Polynomial least-square (PLS) and Taylor series least-square (TLS) procedures are used to estimate the spatial derivatives at each node and their computational efficiencies are compared. Also, the effect of the neighbor stencil selection on the accuracy of the method is investigated. As a new approach, different neighboring stencils are used for the highly stretched point distribution inside the boundary layer region and the inviscid isotropic point distribution outside this area. The unsteady flows over stationary and moving objects at subsonic and transonic flow conditions are solved. Results indicate the computational efficiency of the method in comparison with the alternative approaches. The convergence histories of the flow solution show that the PLS method is computationally faster than TLS method. In addition, the eight point neighboring stencil inside the viscous region is more efficient than other choices.

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“…In this paper, two-equation k-epsilon turbulence model developed with Launder and Spalding (1974) has been applied. The wall-function approach is adopted to treat the near-wall region of the boundary layer (Stolcis andJohnston 1990, Jahangirian andHadidoolabi 2005). In this approach the quantities of interest are evaluated as functions of mean-flow quantities according to the law-of-the-wall.…”

Section: Governing Flow Equationsmentioning

confidence: 99%

“…In turbulent cases, the Reynolds averaged Navier-Stokes equations are used. The computational method applied to solve the problem of surface mass transfer is what is developed in (Stolcis andJohnston 1990, Jahangirian andHadidoolabi 2005). The conservative form of two dimensional unsteady compressible Navier-Stokes equations is:…”

Section: Governing Flow Equationsmentioning

confidence: 99%

Flow Control of Transonic Airfoils using Optimum Suction and Injection Parameters

Moghadam

Jahangirian

2017

JAFM

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In this paper, the application of the surface mass transfer optimization in shock wave-boundary layer interaction control at off-design conditions of transonic aircraft wing is presented. The suction or injection parameters include for example its position on the airfoil, its angle, the length of the hole and the rate of the injected or sucked flow. The optimization process is carried out using an efficient Genetic Algorithm (GA) method. The compressible viscous flow equations in Reynolds Averaged form are solved together with a twoequation k-epsilon turbulence model to accurately compute the objective function. Four different objective functions are introduced including maximum lift to drag ratio, minimum drag coefficient, maximum lift to drag ratio with no drag increment and minimum drag coefficient with no lift decrement. Effectiveness of each objective function is examined by comparing the optimum results in terms of the flow control parameters and flow characteristics.

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Unstructured moving grids for implicit calculation of unsteady compressible viscous flows

Cited by 33 publications

References 6 publications

An Optimum Neural Network for Evolutionary Aerodynamic Shape Design

An Optimum Neural Network for Evolutionary Aerodynamic Shape Design

Unsteady Compressible Flow Calculations with Least-Square Mesh-less Method

Flow Control of Transonic Airfoils using Optimum Suction and Injection Parameters

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