Kaichang Yu , Juan Cheng , Yuanyuan Liu , Chi-Wang Shu
{"title":"High-order implicit maximum-principle-preserving local discontinuous Galerkin methods for convection–diffusion equations","authors":"Kaichang Yu , Juan Cheng , Yuanyuan Liu , Chi-Wang Shu","doi":"10.1016/j.cam.2025.116660","DOIUrl":"10.1016/j.cam.2025.116660","url":null,"abstract":"<div><div>We consider maximum-principle-preserving (MPP) property of two types of implicit local discontinuous Galerkin (LDG) schemes for solving diffusion and convection–diffusion equations. The first one is the original LDG scheme proposed in Cockburn and Shu (1998) with backward Euler time discretization. The second one adds an MPP scaling limiter defined in Zhang and Shu (2010), to the first one. Compared with explicit time discretization, implicit method allows for a larger time step. For pure diffusion equations in 1D, we prove that the second type of the LDG schemes is MPP, which can also achieve high order accuracy. This result can be generalized to 2D by using tensor product meshes but only for the second order <span><math><msup><mrow><mi>Q</mi></mrow><mrow><mn>1</mn></mrow></msup></math></span> case. For convection–diffusion equations, the first type of LDG schemes, in the second order <span><math><msup><mrow><mi>P</mi></mrow><mrow><mn>1</mn></mrow></msup></math></span> case in 1D, is proved to be MPP. In all the results above, in order to achieve the MPP property, it is necessary to have a lower bound on the time step in terms of the Courant–Friedrichs–Lewy (CFL) number. Although the analysis is only performed on linear equations, numerical experiments are provided to demonstrate that the second type of the LDG schemes works well in terms of the MPP property both for nonlinear convection–diffusion equations and for 2D higher order cases.</div></div>","PeriodicalId":50226,"journal":{"name":"Journal of Computational and Applied Mathematics","volume":"470 ","pages":"Article 116660"},"PeriodicalIF":2.1,"publicationDate":"2025-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143838896","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":"Augmented Levin methods for vector-valued highly oscillatory integrals with exotic oscillators and turning points","authors":"Yinkun Wang , Shuhuang Xiang","doi":"10.1016/j.cam.2025.116687","DOIUrl":"10.1016/j.cam.2025.116687","url":null,"abstract":"<div><div>In this paper, we propose an efficient Levin method to approximate vector-valued highly oscillatory integrals with exotic oscillators and turning points. These include integrals involving Hankel functions, the product of Hankel functions with exponential functions, or the product of different Bessel functions. The problem of Levin methods encountering turning points remains an open problem (S. Olver, BIT Numerical Mathematics, 47(3):637-655, 2007). To address the difficulties caused by the turning points, the original Levin ordinary differential equation (Levin-ODE) is converted into augmented ordinary differential equations based on the superposition theory, which can be solved efficiently by the spectral collocation method together with Meijer G-functions. Four kinds of vector-valued highly oscillatory integrals are considered and numerical examples are presented to show the effectiveness and accuracy of the proposed methods.</div></div>","PeriodicalId":50226,"journal":{"name":"Journal of Computational and Applied Mathematics","volume":"470 ","pages":"Article 116687"},"PeriodicalIF":2.1,"publicationDate":"2025-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143829596","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}
Sergei Prokopev , Alexander Nepomnyashchy , Tatyana Lyubimova
{"title":"The spectral radius of iterative methods for the Cahn–Hilliard equation and its relation to the splitting technique","authors":"Sergei Prokopev , Alexander Nepomnyashchy , Tatyana Lyubimova","doi":"10.1016/j.cam.2025.116673","DOIUrl":"10.1016/j.cam.2025.116673","url":null,"abstract":"<div><div>We numerically study the stability of implicit schemes for the Cahn–Hilliard equation. The Cahn–Hilliard equation has an extra limitation for numerical schemes: the total free energy has to be non-increasing with time. One of the most popular remedies for this problem is the splitting technique, when the specific free energy is divided into two parts, one of them is treated explicitly and other one is treated implicitly. We analyse this approach in relation to the spectral radius in the case of Jacobi and Gauss–Seidel methods and show that the linear splitting can lead to the deterioration of a numerical algorithm. We also point out the difference between considering the Cahn–Hilliard equation straightforwardly as the single equation of the 4th order or as the system of two equations of the 2nd order. We propose a simple method to control the spectral radius and increase the stability of iterative methods by adding a stabilizing term, equivalent to adding the artificial time derivative of the chemical potential.</div></div>","PeriodicalId":50226,"journal":{"name":"Journal of Computational and Applied Mathematics","volume":"470 ","pages":"Article 116673"},"PeriodicalIF":2.1,"publicationDate":"2025-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143838895","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 continuous Petrov–Galerkin method for time-fractional Fokker–Planck equation","authors":"Zemian Zhang , Yanping Chen , Yunqing Huang , Jian Huang , Yanping Zhou","doi":"10.1016/j.cam.2025.116689","DOIUrl":"10.1016/j.cam.2025.116689","url":null,"abstract":"<div><div>A continuous Petrov–Galerkin (CPG) method for the time discretization of a time-fractional Fokker–Planck equation with a general driving force involving fractional exponent <span><math><mrow><mi>α</mi><mo>∈</mo><mrow><mo>(</mo><mn>0</mn><mo>,</mo><mn>1</mn><mo>)</mo></mrow></mrow></math></span> is proposed. An <span><math><mi>α</mi></math></span>-robust stability bound for the time discrete solution is obtained for <span><math><mrow><mi>α</mi><mo>∈</mo><mrow><mo>(</mo><mn>1</mn><mo>/</mo><mn>2</mn><mo>,</mo><mn>1</mn><mo>)</mo></mrow></mrow></math></span>. Regarding error analysis, time-graded meshes are utilized to address the singular behavior of the continuous solution near origin. We present the nodal error estimate with non-uniform time meshes and obtain the optimal second-order accurate estimate for <span><math><mrow><mi>α</mi><mo>∈</mo><mrow><mo>(</mo><mn>1</mn><mo>/</mo><mn>2</mn><mo>,</mo><mn>1</mn><mo>)</mo></mrow></mrow></math></span>. The fully-discrete scheme by employing standard (continuous) finite element method in space is considered, and the corresponding error is estimated. Numerical experiments demonstrate that the assumptions of time-graded meshes can be further relaxed, and the results exhibit second-order accuracy for <span><math><mrow><mi>α</mi><mo>∈</mo><mrow><mo>(</mo><mn>0</mn><mo>,</mo><mn>1</mn><mo>)</mo></mrow></mrow></math></span>.</div></div>","PeriodicalId":50226,"journal":{"name":"Journal of Computational and Applied Mathematics","volume":"470 ","pages":"Article 116689"},"PeriodicalIF":2.1,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143842837","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":"Advantages of the Samarskii-type schemes on the Shishkin mesh","authors":"Relja Vulanović , Thái Anh Nhan","doi":"10.1016/j.cam.2025.116688","DOIUrl":"10.1016/j.cam.2025.116688","url":null,"abstract":"<div><div>The schemes of the Samarskii type are simple modifications of the upwind scheme. We use them on the Shishkin mesh and discuss their advantages over the upwind scheme when applied to the linear one-dimensional singularly perturbed convection–diffusion problem. One of the advantages is that the Samarskii-type schemes have <em>exact</em> first-order accuracy uniform in the perturbation parameter, as opposed to the upwind scheme which is <em>almost</em> first-order uniformly accurate because its accuracy is diminished by logarithmic factors. Although this is not a new result, we re-emphasize it in the paper. We also demonstrate another advantage, that the Samarskii-type schemes are almost second-order uniformly accurate on the layer component of the solution. Motivated by this fact, we present a further improvement of the numerical method.</div></div>","PeriodicalId":50226,"journal":{"name":"Journal of Computational and Applied Mathematics","volume":"470 ","pages":"Article 116688"},"PeriodicalIF":2.1,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143824151","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":"Finite element analysis of a pseudostress–pressure–velocity formulation of the stationary Navier–Stokes equations","authors":"M. Farhloul , N. Fall , I. Dione , S. Léger","doi":"10.1016/j.cam.2025.116665","DOIUrl":"10.1016/j.cam.2025.116665","url":null,"abstract":"<div><div>This article is concerned with a dual-mixed formulation of the Navier–Stokes equations which is based on the introduction of the pseudostress as a new unknown. The problem is approximated by a mixed finite element method in two and three dimensions: Raviart–Thomas elements of index <span><math><mrow><mi>k</mi><mo>≥</mo><mn>0</mn></mrow></math></span> for the pseudostress tensor, and piecewise discontinuous polynomials of degree <span><math><mrow><mi>k</mi><mo>≥</mo><mn>0</mn></mrow></math></span> for the velocity and the pressure. An existence result for the finite-element solution and convergence results are proved near a nonsingular solution. Finally, quasi-optimal error estimates, which improve those existing in the literature, are provided.</div></div>","PeriodicalId":50226,"journal":{"name":"Journal of Computational and Applied Mathematics","volume":"469 ","pages":"Article 116665"},"PeriodicalIF":2.1,"publicationDate":"2025-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143808154","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 equivalent fractional optimization problem under invexity conditions for solving fractional vector variational-like inequality problems to portfolio optimization in finance","authors":"Shubham Singh, Shalini","doi":"10.1016/j.cam.2025.116684","DOIUrl":"10.1016/j.cam.2025.116684","url":null,"abstract":"<div><div>This paper introduces and investigates new classes of weak fractional vector variational-like inequalities and fractional vector variational-like inequalities. We establish an equivalence between the efficient solutions of fractional optimization problems and the solutions of introduced inequalities using a parametric approach under generalized invexity assumptions. By applying the KKM Lemma, we prove the existence of solutions for a fractional vector variational-like inequality problem. We also illustrate the derived results with examples. Additionally, we consider an application-based problem in portfolio allocation to validate our findings.</div></div>","PeriodicalId":50226,"journal":{"name":"Journal of Computational and Applied Mathematics","volume":"470 ","pages":"Article 116684"},"PeriodicalIF":2.1,"publicationDate":"2025-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143824150","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":"Composite Tseng-type extragradient algorithms with adaptive inertial correction strategy for solving bilevel split pseudomonotone VIP under split common fixed-point constraint","authors":"Lu-Chuan Ceng , Debdas Ghosh , Habib ur Rehman , Xiaopeng Zhao","doi":"10.1016/j.cam.2025.116683","DOIUrl":"10.1016/j.cam.2025.116683","url":null,"abstract":"<div><div>This paper investigates the bilevel split pseudomonotone variational inequality problem (BSPVIP) and the split common fixed point problem (SCFPP) involving demimetric mappings in real Hilbert spaces. We propose a novel composite Tseng-type extragradient method that incorporates an adaptive inertial correction term to effectively address the BSPVIP under the SCFPP constraints. Our approach combines an inertial technique with a self-adaptive step size strategy to enhance algorithmic efficiency. The BSPVIP consists of an upper-level variational inequality problem for a strongly monotone operator and a lower-level split variational inequality problem for two pseudomonotone operators. Under mild assumptions, we establish the strong convergence of the proposed algorithm. To demonstrate the practical applicability of the method, we apply it to a BSPVIP under split fixed point problem constraints. A numerical example is provided to illustrate the algorithm’s performance and examine the influence of the involved parameters on its behavior.</div></div>","PeriodicalId":50226,"journal":{"name":"Journal of Computational and Applied Mathematics","volume":"470 ","pages":"Article 116683"},"PeriodicalIF":2.1,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143834600","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":"Projection method for steady states of Cahn–Hilliard equation with the dynamic boundary condition","authors":"Shuting Gu , Ming Xiao , Rui Chen","doi":"10.1016/j.cam.2025.116674","DOIUrl":"10.1016/j.cam.2025.116674","url":null,"abstract":"<div><div>The Cahn–Hilliard equation is a fundamental model that describes phase separation processes of two-phase flows or binary mixtures. In recent years, the dynamic boundary conditions for the Cahn–Hilliard equation have been proposed and analyzed. Our first goal in this article is to present a projection method to locate the steady state of the CH equation with dynamic boundary conditions. The main feature of this method is that it only uses the variational derivative in the metric <span><math><msup><mrow><mi>L</mi></mrow><mrow><mn>2</mn></mrow></msup></math></span> and not that in the metric <span><math><msup><mrow><mi>H</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></math></span>, thus significantly reducing the computational cost. In addition, the projected dynamics fulfill the important physical properties: mass conservation and energy dissipation. In the temporal construction of the numerical schemes, the convex splitting method is used to ensure a large time step size. Numerical experiments for the two-dimensional Ginzburg–Landau free energy, where the surface potential is the double well potential or the moving contact line potential, are conducted to demonstrate the effectiveness of this projection method.</div></div>","PeriodicalId":50226,"journal":{"name":"Journal of Computational and Applied Mathematics","volume":"469 ","pages":"Article 116674"},"PeriodicalIF":2.1,"publicationDate":"2025-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143792136","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":"Robust second-order VSBDF2 finite element schemes for parabolic distributed optimal control problems","authors":"Caijie Yang, Tongjun Sun","doi":"10.1016/j.cam.2025.116672","DOIUrl":"10.1016/j.cam.2025.116672","url":null,"abstract":"<div><div>In this paper, we further investigate the variable-step BDF2 (VSBDF2) finite element schemes for solving control constrained distributed optimal control problems governed by parabolic equations, where the state, co-state and control variables are approximated by piecewise linear functions. We first propose the VSBDF2 backward and forward formulas, respectively. Then, motivated by the discrete orthogonal convolution (DOC) and discrete complementary convolution (DCC) backward kernels (Liao and Zhang, 2021; Zhang and Zhao, 2022), we introduce the novel DOC and DCC forward kernels. Utilizing the new analytical tool of backward and forward kernels concerning the DOC and DCC, we can obtain a priori error estimates with the optimal second-order temporal accuracy for the parabolic distributed optimal control problem under the restriction condition <span><math><mrow><mn>1</mn><mo>/</mo><mn>4</mn><mo>.</mo><mn>8645</mn><mo>⩽</mo><msub><mrow><mi>r</mi></mrow><mrow><mi>k</mi></mrow></msub><mo>⩽</mo><mn>4</mn><mo>.</mo><mn>8645</mn></mrow></math></span>. Moreover, our analysis also shows that the initial solutions <span><math><msup><mrow><mi>y</mi></mrow><mrow><mn>1</mn></mrow></msup></math></span> and <span><math><msup><mrow><mi>p</mi></mrow><mrow><mi>N</mi><mo>−</mo><mn>1</mn></mrow></msup></math></span> obtained by VSBDF1 backward and forward formulas (i.e., the variable-step backward and forward Euler formulas) do not result in the loss of accuracy with <span><math><mrow><mn>1</mn><mo>/</mo><mn>4</mn><mo>.</mo><mn>8645</mn><mo>⩽</mo><msub><mrow><mi>r</mi></mrow><mrow><mi>k</mi></mrow></msub><mo>⩽</mo><mn>4</mn><mo>.</mo><mn>8645</mn></mrow></math></span>. Numerical experiments are provided to validate our theoretical analysis.</div></div>","PeriodicalId":50226,"journal":{"name":"Journal of Computational and Applied Mathematics","volume":"469 ","pages":"Article 116672"},"PeriodicalIF":2.1,"publicationDate":"2025-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143792137","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}