{"title":"Mixed Finite Element Methods for Linear Cosserat Equations","authors":"W. M. Boon, O. Duran, J. M. Nordbotten","doi":"10.1137/24m1648387","DOIUrl":"https://doi.org/10.1137/24m1648387","url":null,"abstract":"SIAM Journal on Numerical Analysis, Volume 63, Issue 1, Page 306-333, February 2025. <br/> Abstract. We consider the equilibrium equations for a linearized Cosserat material and provide two perspectives concerning well-posedness. First, the system can be viewed as the Hodge–Laplace problem on a differential complex. On the other hand, we show how the Cosserat materials can be analyzed by inheriting results from linearized elasticity. Both perspectives give rise to mixed finite element methods, which we refer to as strongly and weakly coupled, respectively. We prove convergence of both classes of methods, with particular attention to improved convergence rate estimates, and stability in the limit of vanishing characteristic length of the micropolar structure. The theoretical results are fully reflected in the actual performance of the methods, as shown by the numerical verifications.","PeriodicalId":49527,"journal":{"name":"SIAM Journal on Numerical Analysis","volume":"62 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143258690","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Second Order Exponential Splittings in the Presence of Unbounded and Time-Dependent Operators: Construction and Convergence","authors":"K. Kropielnicka, J. C. Del Valle","doi":"10.1137/23m1607660","DOIUrl":"https://doi.org/10.1137/23m1607660","url":null,"abstract":"SIAM Journal on Numerical Analysis, Volume 63, Issue 1, Page 288-305, February 2025. <br/> Abstract. For linear differential equations of the form [math], [math], with a possibly unbounded operator [math], we construct and deduce error bounds for two families of second-order exponential splittings. The role of quadratures when integrating the twice-iterated Duhamel’s formula is reformulated: we show that their choice defines the structure of the splitting. Furthermore, the reformulation allows us to consider quadratures based on the Birkhoff interpolation to obtain splittings featuring not only exponentials of [math] or [math] but also time-derivatives of [math] and commutators of [math] and [math]. In this approach, the construction and error analysis of the splittings are carried out simultaneously. We discuss the accuracy of the members of the families. Numerical experiments are presented to complement the theoretical consideration.","PeriodicalId":49527,"journal":{"name":"SIAM Journal on Numerical Analysis","volume":"40 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143084051","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Multilevel Monte Carlo Methods for the Dean–Kawasaki Equation from Fluctuating Hydrodynamics","authors":"Federico Cornalba, Julian Fischer","doi":"10.1137/23m1617345","DOIUrl":"https://doi.org/10.1137/23m1617345","url":null,"abstract":"SIAM Journal on Numerical Analysis, Volume 63, Issue 1, Page 262-287, February 2025. <br/> Abstract. Stochastic PDEs of fluctuating hydrodynamics are a powerful tool for the description of fluctuations in many-particle systems. In this paper, we develop and analyze a multilevel Monte Carlo (MLMC) scheme for the Dean–Kawasaki equation, a pivotal representative of this class of SPDEs. We prove analytically and demonstrate numerically that our MLMC scheme provides a significant reduction in computational cost (with respect to a standard Monte Carlo method) in the simulation of the Dean–Kawasaki equation. Specifically, we link this reduction in cost to having a sufficiently large average particle density and show that sizeable cost reductions can be obtained even when we have solutions with regions of low density. Numerical simulations are provided in the two-dimensional case, confirming our theoretical predictions. Our results are formulated entirely in terms of the law of distributions rather than in terms of strong spatial norms: this crucially allows for MLMC speed-ups altogether despite the Dean–Kawasaki equation being highly singular.","PeriodicalId":49527,"journal":{"name":"SIAM Journal on Numerical Analysis","volume":"19 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143071527","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A Priori Analysis of a Tensor ROM for Parameter Dependent Parabolic Problems","authors":"Alexander V. Mamonov, Maxim A. Olshanskii","doi":"10.1137/23m1616844","DOIUrl":"https://doi.org/10.1137/23m1616844","url":null,"abstract":"SIAM Journal on Numerical Analysis, Volume 63, Issue 1, Page 239-261, February 2025. <br/> Abstract. A space–time–parameters structure of parametric parabolic PDEs motivates the application of tensor methods to define reduced order models (ROMs). Within a tensor-based ROM framework, the matrix SVD—a traditional dimension reduction technique—yields to a low-rank tensor decomposition (LRTD). Such tensor extension of the Galerkin proper orthogonal decomposition ROMs (POD–ROMs) benefits both the practical efficiency of the ROM and its amenability for rigorous error analysis when applied to parametric PDEs. The paper addresses the error analysis of the Galerkin LRTD–ROM for an abstract linear parabolic problem that depends on multiple physical parameters. An error estimate for the LRTD–ROM solution is proved, which is uniform with respect to problem parameters and extends to parameter values not in a sampling/training set. The estimate is given in terms of discretization and sampling mesh properties and LRTD accuracy. The estimate depends on the local smoothness rather than on the Kolmogorov [math]-widths of the parameterized manifold of solutions. Theoretical results are illustrated with several numerical experiments.","PeriodicalId":49527,"journal":{"name":"SIAM Journal on Numerical Analysis","volume":"24 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143055038","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Numerical Approximation of Discontinuous Solutions of the Semilinear Wave Equation","authors":"Jiachuan Cao, Buyang Li, Yanping Lin, Fangyan Yao","doi":"10.1137/24m1635879","DOIUrl":"https://doi.org/10.1137/24m1635879","url":null,"abstract":"SIAM Journal on Numerical Analysis, Volume 63, Issue 1, Page 214-238, February 2025. <br/> Abstract. A high-frequency recovered fully discrete low-regularity integrator is constructed to approximate rough and possibly discontinuous solutions of the semilinear wave equation. The proposed method, with high-frequency recovery techniques, can capture the discontinuities of the solutions correctly without spurious oscillations and approximate rough and discontinuous solutions with a higher convergence rate than preexisting methods. Rigorous analysis is presented for the convergence rates of the proposed method in approximating solutions such that [math] for [math]. For discontinuous solutions of bounded variation in one dimension (which allow jump discontinuities), the proposed method is proved to have almost first-order convergence under the step size condition [math], where [math] and [math] denote the time step size and the number of Fourier terms in the space discretization, respectively. Numerical examples are presented in both one and two dimensions to illustrate the advantages of the proposed method in improving the accuracy in approximating rough and discontinuous solutions of the semilinear wave equation. The numerical results are consistent with the theoretical results and show the efficiency of the proposed method.","PeriodicalId":49527,"journal":{"name":"SIAM Journal on Numerical Analysis","volume":"20 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143050861","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Criticality Measure-Based Error Estimates for Infinite Dimensional Optimization","authors":"Danlin Li, Johannes Milz","doi":"10.1137/24m1647023","DOIUrl":"https://doi.org/10.1137/24m1647023","url":null,"abstract":"SIAM Journal on Numerical Analysis, Volume 63, Issue 1, Page 193-213, February 2025. <br/> Abstract. Motivated by optimization with differential equations, we consider optimization problems with Hilbert spaces as decision spaces. As a consequence of their infinite dimensionality, the numerical solution necessitates finite dimensional approximations and discretizations. We develop an approximation framework and demonstrate criticality measure-based error estimates. We consider criticality measures inspired by those used within optimization methods, such as semismooth Newton and (conditional) gradient methods. Furthermore, we show that our error estimates are optimal. Our findings augment existing distance-based error estimates but do not rely on strong convexity or second-order sufficient optimality conditions. Moreover, our error estimates can be used for code verification and validation. We illustrate our theoretical convergence rates on linear, semilinear, and bilinear PDE-constrained optimization problems.","PeriodicalId":49527,"journal":{"name":"SIAM Journal on Numerical Analysis","volume":"111 3S 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143026661","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ulrik S. Fjordholm, Kenneth H. Karlsen, Peter H. C. Pang
{"title":"Convergent Finite Difference Schemes for Stochastic Transport Equations","authors":"Ulrik S. Fjordholm, Kenneth H. Karlsen, Peter H. C. Pang","doi":"10.1137/23m159946x","DOIUrl":"https://doi.org/10.1137/23m159946x","url":null,"abstract":"SIAM Journal on Numerical Analysis, Volume 63, Issue 1, Page 149-192, February 2025. <br/> Abstract. We present difference schemes for stochastic transport equations with low-regularity velocity fields. We establish [math] stability and convergence of the difference approximations under conditions that are less strict than those required for deterministic transport equations. The [math] estimate, crucial for the analysis, is obtained through a discrete duality argument and a comprehensive examination of a class of backward parabolic difference schemes.","PeriodicalId":49527,"journal":{"name":"SIAM Journal on Numerical Analysis","volume":"52 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143020597","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Orthogonal Polynomial Approximation and Extended Dynamic Mode Decomposition in Chaos","authors":"Caroline Wormell","doi":"10.1137/23m1597873","DOIUrl":"https://doi.org/10.1137/23m1597873","url":null,"abstract":"SIAM Journal on Numerical Analysis, Volume 63, Issue 1, Page 122-148, February 2025. <br/> Abstract. Extended dynamic mode decomposition (EDMD) is a data-driven tool for forecasting and model reduction of dynamics, which has been extensively taken up in the physical sciences. While the method is conceptually simple, in deterministic chaos it is unclear what its properties are or even what it converges to. In particular, it is not clear how EDMD’s least-squares approximation treats the classes of differentiable functions on which chaotic systems act. We develop for the first time a general, rigorous theory of EDMD on the simplest examples of chaotic maps: analytic expanding maps of the circle. To do this, we prove a new, basic approximation result in the theory of orthogonal polynomials on the unit circle (OPUC) and apply methods from transfer operator theory. We show that in the infinite-data limit, the least-squares projection error is exponentially small for trigonometric polynomial observable dictionaries. As a result, we show that forecasts and Koopman spectral data produced using EDMD in this setting converge to the physically meaningful limits, exponentially fast with respect to the size of the dictionary. This demonstrates that with only a relatively small polynomial dictionary, EDMD can be very effective, even when the sampling measure is not uniform. Furthermore, our OPUC result suggests that data-based least-squares projection may be a very effective approximation strategy more generally.","PeriodicalId":49527,"journal":{"name":"SIAM Journal on Numerical Analysis","volume":"107 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142990649","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"An Energy-Stable Parametric Finite Element Method for the Planar Willmore Flow","authors":"Weizhu Bao, Yifei Li","doi":"10.1137/24m1633893","DOIUrl":"https://doi.org/10.1137/24m1633893","url":null,"abstract":"SIAM Journal on Numerical Analysis, Volume 63, Issue 1, Page 103-121, February 2025. <br/> Abstract. We propose an energy-stable parametric finite element method (PFEM) for the planar Willmore flow and establish its unconditional energy stability of the full discretization scheme. The key lies in the introduction of two novel geometric identities to describe the planar Willmore flow: the first involves the coupling of the outward unit normal vector [math] and the normal velocity [math], and the second concerns the time derivative of the mean curvature [math]. Based on these, we derive a set of new geometric partial differential equations for the planar Willmore flow, leading to our new fully discretized and unconditionally energy-stable PFEM. Our stability analysis is also based on the two new geometric identities. Extensive numerical experiments are provided to illustrate our PFEM’s efficiency and validate its unconditional energy stability.","PeriodicalId":49527,"journal":{"name":"SIAM Journal on Numerical Analysis","volume":"9 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142967963","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"VEM-Nitsche Fully Discrete Polytopal Scheme for Frictionless Contact-Mechanics","authors":"Mohamed Laaziri, Roland Masson","doi":"10.1137/24m1660218","DOIUrl":"https://doi.org/10.1137/24m1660218","url":null,"abstract":"SIAM Journal on Numerical Analysis, Volume 63, Issue 1, Page 81-102, February 2025. <br/> Abstract. This work targets the discretization of contact-mechanics accounting for small strains, linear elastic constitutive laws, and fractures or faults represented as a network of co-dimension one planar interfaces. This type of model coupled with Darcy flow plays an important role typically for the simulation of fault reactivation by fluid injection in geological storage or the hydraulic fracture stimulation in enhanced geothermal systems. To simplify the presentation, a frictionless contact behavior at matrix fracture interfaces is considered, although the scheme developed in this work readily extends to more complex contact models such as the Mohr–Coulomb friction. To account for the geometrical complexity of subsurface, our discretization is based on the first order virtual element method (VEM), which generalizes the [math] finite element method to polytopal meshes. Following previous works in the finite element framework, the contact conditions are enforced in a weak sense using Nitsche’s formulation based on additional consistent penalization terms. We perform, in a fully discrete framework, the well-posedness and convergence analysis showing an optimal first order error estimate with minimal regularity assumptions. Numerical experiments confirm our theoretical findings and exhibit the good behavior of the nonlinear semismooth Newton solver.","PeriodicalId":49527,"journal":{"name":"SIAM Journal on Numerical Analysis","volume":"30 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142936909","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}