scholarly journals A RESONANCE CALCULATION METHOD USING ENERGY EXPANSION BASED ON A REDUCED ORDER MODEL: USE OF ULTRA-FINE GROUP SPECTRUM CALCULATION AND APPLICATION TO HETEROGENEOUS GEOMETRY

2021 ◽  
Vol 247 ◽  
pp. 02006
Author(s):  
Ryoichi Kondo ◽  
Tomohiro Endo ◽  
Akio Yamamoto ◽  
Satoshi Takeda ◽  
Hiroki Koike ◽  
...  
Keyword(s):  
Cross Sections ◽  
Interference Effect ◽  
Spectral Expansion ◽  
Orthogonal Basis ◽  
Order Model ◽  
Reduced Order ◽  
Mox Fuel ◽  
Transport Calculation ◽  
Expansion Coefficients ◽  
Value Decomposition

A Resonance calculation using energy Spectral Expansion (RSE) method has been recently proposed in order to efficiently treat complicated heterogeneous geometry and resonance interference effect. In the RSE method, ultra-fine group spectra are generated from ultra-fine group calculations in homogeneous geometry, and the spectra are expanded by the orthogonal basis on energy based on the singular value decomposition. Then the transport calculation for expansion coefficients is numerically performed, and the ultra-fine group spectra in the target heterogeneous regions are reconstructed by the expansion coefficients and the orthogonal basis. In this study, the RSE method is applied to multi-cell geometries including UO2, MOX and water cells, in which the resonance interference effect between UO2 and MOX fuel cells appears. The validity of the RSE method is confirmed through comparison with the reference effective multi-group cross sections obtained from the direct ultra-fine group calculation in the target heterogeneous geometry.

scholarly journals Reduced-Order Modeling Based on Hybrid Snapshot Simulation

2020 ◽  
Vol 18 (01) ◽  
pp. 2050029 ◽  
Author(s):  
Feng Bai ◽  
Yi Wang
Keyword(s):  
Quality Data ◽  
Data Generation ◽  
Order Model ◽  
High Quality Data ◽  
Reduced Order ◽  
Online Simulation ◽  
Data Fidelity ◽  
Value Decomposition ◽  
Proper Orthogonal ◽  
Traditional Counterpart

This paper presents a hybrid snapshot simulation methodology to accelerate the generation of high-quality data for proper orthogonal decomposition (POD) and reduced-order model (ROM) development. The entire span of the snapshot simulation is divided into multiple intervals, each simulated by either high-fidelity full-order model (FOM) or fast local ROM. The simulation then alternates between FOM and local ROM to accelerate snapshot data generation while maintaining the data fidelity and representation. Model switch is determined on-the-fly by evaluating several criteria that monitor the dominance of leading POD modes and ROM trajectory. The incremental singular value decomposition (iSVD) is employed to continuously update ROMs for enhanced accuracy and utilization. A global ROM broadly applicable to various online simulation is immediately available at the end of the simulation. The hybrid snapshot simulation demonstrates excellent accuracy ([Formula: see text] error) and 2.09–2.6[Formula: see text]X speedup relative to its traditional counterpart. The constructed ROMs also preserve salient accuracy ([Formula: see text] error). The results prove feasibility of the proposed method for robust and efficient snapshot data generation and ROM development.

A Substructure Based Reduced Order Model for Mistuned Bladed Disks

2009 ◽  
Author(s):  
Andreas Hohl ◽  
Christian Siewert ◽  
Lars Panning ◽  
Jo¨rg Wallaschek
Keyword(s):  
Degrees Of Freedom ◽  
Normal Modes ◽  
Forced Response ◽  
Component Mode Synthesis ◽  
Order Model ◽  
Bladed Disks ◽  
Reduced Order ◽  
Symmetry Approach ◽  
Full Structure ◽  
Value Decomposition

A efficient method for the calculation of the forced response of mistuned bladed disks is introduced. Based on the Component Mode Synthesis techniques the structure is divided into substructures, namely the disk and the blades. The Component Mode Synthesis of the disk is calculated with a fast and accurate cyclic symmetry approach. A recently developed method called Wave Based Substructuring is used to describe the (numerous) coupling degrees of freedom between the disk and the blades. The orthogonal waves are derived with a Singular Value Decomposition or a QR decomposition from the coupling nodes’ normal modes calculated by a modal analysis of the full structure.

Reduced-Order Modeling of Conjugate Heat Transfer Processes

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Trevor J. Blanc ◽  
Matthew R. Jones ◽  
Steven E. Gorrell
Keyword(s):  
Heat Transfer ◽  
Conjugate Heat Transfer ◽  
Reduced Order Modeling ◽  
Order Model ◽  
Linear Combinations ◽  
Reduced Order ◽  
Transfer Processes ◽  
Modeling Techniques ◽  
Expansion Coefficients ◽  
Basis Vectors

This paper describes the application of reduced-order modeling techniques in the simulation of conjugate heat transfer processes. In a reduced-order model (ROM), the dominate features of a system are represented using a limited number of orthonormal basis vectors, which are extracted from a database containing descriptions of the system. Interpolating methods are then used to calculate expansion coefficients that allow representation of the system as linear combinations of the basis vectors. Evidence of the accuracy and computational savings achieved using the reduced-order modeling technique is presented in order to demonstrate its benefits in simulating conjugate heat transfer processes.

scholarly journals A high fidelity cost efficient tensorial method based on combined POD-HOSVD reduced order model of flow field

2018 ◽  
Author(s):  
Mohammad Kazem Moayyedi ◽  
Milad Najaf Beygi
Keyword(s):  
Flow Field ◽  
Data Storage ◽  
Computation Time ◽  
Order Model ◽  
Reduced Order ◽  
Naca0012 Airfoil ◽  
Computational Speed ◽  
Cost Efficient ◽  
Value Decomposition ◽  
Proper Orthogonal

Computation time and data storage is a significant challenge in every calculation process. Increasing computational speed by upgrading hardware and the introduction of new software are some of the techniques to overcome this challenge. One of the most interesting methods for fast computations is the reduced order frameworks. In this study, the aerodynamic coefficients of the NACA0012 airfoil in subsonic and supersonic flows have been reconstructed and estimated by a cost-efficient form of combined proper orthogonal decomposition–high-order singular value decomposition (POD-HOSVD) scheme. The initial data ensemble contains some members related to the variations of the angle of attack and Mach number. To reduce the computation time, the structure of the standard combined POD-HOSVD approach has been changed to a cost-efficient format. The present method is a grid independent formulation of standard combined POD-HOSVD for the fields with a large number of elements and several effective variables. Results indicate more than 90 percent reduction in the calculation time compares with computational fluid dynamics and standard combined POD-HOSVD methods for a subsonic flow field.

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