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Showing 1 to 16 of 16 for “"discrete adjoint"”.
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Applications of the Discrete Adjoint Method in Computational Fluid Dynamics
The discrete adjoint method allows efficient evaluation of the derivative of a function I(s) with respect to parameters s in situations where I depends on s indirectly, via an intermediate variable w(s), which is computationally expensive to evaluate. In this thesis two applications of this method …
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Aerodynamic Design Sensitivities on an Unstructured Mesh Using the Navier-Stokes Equations and a Discrete Adjoint Formulation
A discrete adjoint method is developed and demonstrated for aerodynamic design optimization on unstructured grids. The governing equations are the three-dimensional Reynolds-averaged Navier-Stokes equations coupled with a one-equation turbulence model. A discussion of the numerical implementation …
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Discrete Adjoints: Theoretical Analysis, Efficient Computation, and Applications
… provides directional derivatives and discrete adjoints with working accuracy. A complete complexity analysis of the basic modes of automatic differentiation is available. Therefore, the research activities are focused now on different aspects of the derivative calculation, as for …
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An exact and consistent adjoint method for high-fidelity discretization of the compressible flow equations
… improvement. Gradient-based optimization using adjoints can circumvent the flow complexity to guide designs. Such methods have enabled sensitivity analysis and active control of turbulence at engineering flow conditions by providing gradient information at computational cost comparable to that …
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Adjoint-based space-time adaptive solution algorithms for sensitivity analysis and inverse problems
… mesh refinement, adaptive time steps, and the discrete adjoint method. This dissertation develops a complete framework for fully discrete adjoint sensitivity analysis and inverse problem solutions, in the context of time dependent, adaptive mesh, and adaptive step models. The discrete framework …
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An a posteriori error control framework for adaptive precision optimization using discontinuous Galerkin finite element method
… significant development over the past decade. Adjoint-based shape design for elliptic systems was first proposed by Pironneau and applied to transonic flow by Jameson . A review of the aerodynamic shape optimization literature and a large list of references is given in. Over the years much …
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Computational design for electromagnetic simulations
… field simulation tool, an original adjoint routine for obtaining sensitivity derivatives, and an original grid-smoothing tool with an existing optimization package. The electromagnetic field simulation software employs a temporally and spatially higher-order accurate Streamline …
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Development of S3D and Adjoint Design Methods for Efficient Aerodynamic Design of Three-Dimensional High-Speed Compressor Blades
In the second part of the study, an adjoint design method was employed for compressor design to broaden the range of design capability, to facilitate 3D design applications, and to complement the S3D design method. An adjoint design code was developed, based on a 3D compressor flow analysis code, …
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Quantifying high-resolution hydrologic parameters at the basin scale using InSAR and inverse modeling, Las Vegas Valley, NV
… stand-alone chapters. Chapter 2 presents a discrete adjoint parameter estimation (APE) algorithm for automatically identifying suitable hydraulic parameter zonations from hydraulic head and subsidence measurements. Chapter 3 compares three different inversion strategies to determine the most …
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Time-dependent adjoint-based optimization of photonic crystals and metamaterials using a stabilized finite element method
In the current research, a time-dependent discrete adjoint algorithm for optimization of electromagnetic problems is developed. The proposed algorithm improves the efficiency for gradient-based optimization. The time-dependent Maxwell equations are discretized using a semi-discrete Petrov-Galerkin …
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Computational Tools for Chemical Data Assimilation with CMAQ
… for atmospheric pollution studies. CMAQ-ADJ, the adjoint model of CMAQ, offers new analysis capabilities such as receptor-oriented sensitivity analysis and chemical data assimilation. This thesis presents the construction, validation, and properties of new adjoint modules in CMAQ, and illustrates …
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Adjoint-based optimization for hyperbolic balance laws in the presence of discontinuities
… in optimization in multiphase flows using discrete adjoint-based methods. The main issues we will endeavor to study are the impact on the linearized and adjoint equations of discontinuous solutions, the behavior of the THINC-family of numerical schemes under linearization and the rigorous …
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Sensitivity analysis and optimization in low order thermoacoustic models
… thesis a wave-based network model is used. Using adjoint methods the gradients of the eigenvalue with respect to system parameters can be obtained at a low computational cost. This information is used as an input to an optimization routine to find stable thermoacoustic configurations. In this …
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Adjoint sensitivity analysis of the atmospheric impacts of combustion emissions
… is computationally expensive. Atmospheric adjoint modeling enables the calculation of receptor-oriented sensitivities of environmental metrics of interest to emissions, overcoming the numerical cost of conventional modeling. This thesis applies and further develops an existing adjoint of a …
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Design, Analysis, and Application of Immersed Finite Element Methods
… are all reduced to key properties of the related discrete extension operator. We employ these results to show the optimal convergence of a discontinuous Galerkin IFE (DGIFE) method. In the last part, we apply the linear IFE methods in the literature together with the shape optimization technique …
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Design optimization for 2-D granular media with dissipation
… or lack thereof as the design variable is a discrete optimization problem. It is necessary to make the problem tractable by convexifying the design space. The intruders presence (or non-presence) are replaced by their volume fraction. A penalty term in the cost function is used to recover the …