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On the Spurious Mode Generation Induced by Spectral-Like Optimized Interpolation Schemes Used in Computational Acoustics

Guilherme Cunha, Stéphane Redonnet
2016 Communications in Computational Physics  
More precisely, we address here the interpolation process, which is more and more frequently used in Computational Acoustics–whether it is for enabling multi-stage hybrid calculations, or for easing the  ...  proper handling of complex configurations via advanced techniques such as Chimera grids or Immersed Boundary Conditions.  ...  Acknowledgements The authors would like to thank Professor Michael Jolly for his help with the Big Red II supercomputer at Indiana and his current collaboration on 16 research treating measurement and  ... 
doi:10.4208/cicp.060515.161115a fatcat:odm7d53w7bh4hbggfki3s6ziaa

A data-assimilation method for Reynolds-averaged Navier–Stokes-driven mean flow reconstruction

Dimitry P. G. Foures, Nicolas Dovetta, Denis Sipp, Peter J. Schmid
2014 Journal of Fluid Mechanics  
We present a data-assimilation technique based on a variational formulation and a Lagrange multipliers approach to enforce the Navier-Stokes equations.  ...  The data-assimilation algorithm is derived to minimize the error between a mean flow measurement and the measure performed on a numerical solution of the steady, forced Navier-Stokes equations; the optimal  ...  We present a data-assimilation technique based on a variational formulation and a Lagrange multipliers approach to enforce the Navier-Stokes equations.  ... 
doi:10.1017/jfm.2014.566 fatcat:zynfapivnfenfbybjksytx7vcu

Dynamically learning the parameters of a chaotic system using partial observations

Elizabeth Carlson, Joshua Hudson, Adam Larios, Vincent R. Martinez, Eunice Ng, Jared P. Whitehead
2022 Discrete and Continuous Dynamical Systems. Series A  
<p style='text-indent:20px;'>Motivated by recent progress in data assimilation, we develop an algorithm to dynamically learn the parameters of a chaotic system from partial observations.  ...  Such a result appears to be the first of its kind for dynamical parameter estimation of nonlinear systems.  ...  the land continue to this day.  ... 
doi:10.3934/dcds.2022033 fatcat:2egpjv3wprdtleuajebab7zbv4

Dynamically learning the parameters of a chaotic system using partial observations [article]

Elizabeth Carlson, Joshua Hudson, Adam Larios, Vincent R. Martinez, Eunice Ng, Jared P. Whitehead
2021 arXiv   pre-print
Motivated by recent progress in data assimilation, we develop an algorithm to dynamically learn the parameters of a chaotic system from partial observations.  ...  Under reasonable assumptions, we rigorously establish the convergence of this algorithm to the correct parameters when the system in question is the classic three-dimensional Lorenz system.  ...  As a data assimilation algorithm, this was first studied for the Lorenz equations and 2D Navier-Stokes equations in [47] .  ... 
arXiv:2108.08354v1 fatcat:scvovu6cancftk2ahbsugu3hai

An Efficient Continuous Data Assimilation Algorithm for the Sabra Shell Model of Turbulence [article]

Nan Chen, Yuchen Li, Evelyn Lunasin
2021 arXiv   pre-print
In this article, an efficient continuous in time data assimilation scheme is developed, which exploits closed analytic formulae for updating the unobserved state variables.  ...  Recovering unobserved state variables is an important topic for the data assimilation of turbulent systems.  ...  With some minor approximations, many complex turbulent partial differential equations (PDEs), such as the Navier-Stokes equations (NSE), can be written into the form of (1) 7-9 (see Section II B).  ... 
arXiv:2105.10020v1 fatcat:jwgcjsmybrg3hopgpjkv343qki

Filter accuracy for the Lorenz 96 model: Fixed versus adaptive observation operators

K.J.H. Law, D. Sanz-Alonso, A. Shukla, A.M. Stuart
2016 Physica D : Non-linear phenomena  
We consider discrete-time and continuous-time observations in our theoretical developments.  ...  We prove that, for fixed observation operator, the 3DVAR filter can recover the system state within a neighbourhood determined by the size of the observational noise.  ...  AbS and DSA are supported by the EPSRC-MASDOC graduate training scheme. AMS is supported by EPSRC, ERC and ONR.  ... 
doi:10.1016/j.physd.2015.12.008 fatcat:f5v4udde5rh6hpn3de7fcw6k4a

Concurrent multi-parameter learning demonstrated on the Kuramoto-Sivashinsky equation [article]

Benjamin Pachev, Jared P. Whitehead, Shane A. McQuarrie
2022 arXiv   pre-print
We develop an algorithm based on the nudging data assimilation scheme for the concurrent (on-the-fly) estimation of scalar parameters for a system of evolutionary dissipative partial differential equations  ...  The intuitive nature of the algorithm makes its extension to several different systems immediate, and it allows for recovery of multiple parameters simultaneously.  ...  Ng for their helpful discussions, as well as the reviewers for their very helpful feedback which led to significant improvements in the manuscript.  ... 
arXiv:2106.06069v2 fatcat:jb2hsdgcljburdhj5p7fd7jfz4

Computational methods in cardiovascular mechanics [article]

Ferdinando Auricchio, Michele Conti, Adrian Lefieux, Simone Morganti, Alessandro Reali, Gianluigi Rozza, Alessandro Veneziani
2018 arXiv   pre-print
noninvasive, approach for understanding not only basic mechanisms but also patient-specific conditions, and for supporting the design and the development of new therapeutic options.  ...  The introduction of computational models in cardiovascular sciences has been progressively bringing new and unique tools for the investigation of the physiopathology.  ...  For low Reynolds, ≈ , so to be consistent with the original Navier-Stokes equations (1).  ... 
arXiv:1803.04535v1 fatcat:otfacfb75bebdisazlovgrln5y

Augmented Stabilized and Galerkin Least Squares Formulations

Rakesh Ranjan, Yusheng Feng, Anthony Theodore Chronopolous
2016 Journal of Mathematics Research  
Higher order spectral/$hp$ approximations are utilized for solving two dimensional computational fluid dynamics (CFD) problems with the new formulations named as the Augmented SUPS (ASUPS) and Augmented  ...  Inexact Newton Krylov methods are used as the non-linear solvers of choice for the problems studied. Faithful representations<br />of all fields of interest are obtained for the problems tested.  ...  We consider the dimensional form of the Navier-Stokes equations for the development of the ASUPS formulation.  ... 
doi:10.5539/jmr.v8n6p1 fatcat:kvbxonkeazfgbeaorgoeft34r4

Experimental uncertainty of measured entropy production with pulsed laser PIV and planar laser induced fluorescence

O.B. Adeyinka, G.F. Naterer
2005 International Journal of Heat and Mass Transfer  
Al-Baali M Extra-updates criterion for the limited memory BFGS algorithm for large scale nonlinear optimization J COMPLEXITY 18 (2), pp 557-572 2002 8.  ...  The use of satellite scatterometer winds to drive a primitive equation model of the Indian-ocean -the impact of b and-like sampling.  ...  Fourestey G, Moubachir M, Solving inverse problems involving the Navier-Stokes equations discretized by a Lagrange-Galerkin method.  ... 
doi:10.1016/j.ijheatmasstransfer.2004.10.021 fatcat:puy7vw5fgbhtfe3qqu6t66lqg4

Variational fluid flow measurements from image sequences: synopsis and perspectives

Dominique Heitz, Etienne Mémin, Christoph Schnörr
2009 Experiments in Fluids  
We outline promising research directions and point out the potential of variational techniques in combination with correlation-based PIV methods, for improving the consistency of fluid flow estimation  ...  Variational approaches to image motion segmentation has been an active field of study in image processing and computer vision for two decades.  ...  With a three-dimensional perfect visualization of the flow, the estimated three-dimensional optical flow should obviously obey to the full Navier-Stokes equations, and the evolution of the three-dimensional  ... 
doi:10.1007/s00348-009-0778-3 fatcat:p2voujunsrdwxasipwp6ve5syq

Data-driven deconvolution for large eddy simulations of Kraichnan turbulence

R. Maulik, O. San, A. Rasheed, P. Vedula
2018 Physics of Fluids  
Both a priori and a posteriori results are shown for a two-dimensional decaying turbulence case in addition to a detailed description of validation and testing.  ...  Through this we seek to unite structural and functional modeling strategies for modeling non-linear partial differential equations using reduced degrees of freedom.  ...  simulation data in order to close the two-dimensional Navier-Stokes equations.  ... 
doi:10.1063/1.5079582 fatcat:isolvrnv4bdihkstq52xu6hame

Data-driven deconvolution for large eddy simulations of Kraichnan turbulence [article]

Romit Maulik, Omer San, Adil Rasheed, Prakash Vedula
2018 arXiv   pre-print
Both a priori and a posteriori results are shown for a two-dimensional decaying turbulence case in addition to a detailed description of validation and testing.  ...  Through this we seek to unite structural and functional modeling strategies for modeling non-linear partial differential equations using reduced degrees of freedom.  ...  simulation data in order to close the two-dimensional Navier-Stokes equations.  ... 
arXiv:1812.02211v1 fatcat:oga3runu35e3rclgm3cxgr4bii

Data-driven cardiovascular flow modeling: examples and opportunities [article]

Amirhossein Arzani, Scott T. M. Dawson
2021 arXiv   pre-print
In particular, we discuss principal component analysis (PCA), robust PCA, compressed sensing, the Kalman filter for data assimilation, low-rank data recovery, and several additional methods for reduced-order  ...  in parameters, low spatiotemporal resolution, and measurement noise.  ...  Data Availability The codes and data used to generate the results in the manuscript will be made publicly available after peer-review. p. 30  ... 
arXiv:2010.00131v2 fatcat:kgjzb4mup5amjdnfipoekthm4q

Stochastic Dynamics of Plant-Water Interactions

Gabriel Katul, Amilcare Porporato, Ram Oren
2007 Annual Review of Ecology, Evolution and Systematics  
stochasticity to preserve the probabilistic and spectral information content of the high dimensional system.  ...  This challenge is not surprising given the high dimensionality and degree of nonlinearity of the soil-plant system, which evolves in space and time according to complex internal physical, chemical, and  ...  atmosphere must be accounted for as dynamic boundary conditions to the Navier-Stokes equations (Albertson et al. 2001) .  ... 
doi:10.1146/annurev.ecolsys.38.091206.095748 fatcat:pn7dgqxjkneaxb3qxocz5rq5le
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