{"title":"A high-order accurate unconditionally stable bound-preserving numerical scheme for the Cahn-Hilliard-Navier-Stokes equations","authors":"Yali Gao , Daozhi Han , Sayantan Sarkar","doi":"10.1016/j.apnum.2025.06.004","DOIUrl":"10.1016/j.apnum.2025.06.004","url":null,"abstract":"<div><div>A high order numerical method is developed for solving the Cahn-Hilliard-Navier-Stokes equations with the Flory-Huggins potential. The scheme is based on the <span><math><msub><mrow><mi>Q</mi></mrow><mrow><mi>k</mi></mrow></msub></math></span> finite element with mass lumping on rectangular grids, the second-order convex splitting method and the pressure correction method. The unique solvability, unconditional stability, and bound-preserving properties are rigorously established. The key for bound-preservation is the discrete <span><math><msup><mrow><mi>L</mi></mrow><mrow><mn>1</mn></mrow></msup></math></span> estimate of the singular potential. Ample numerical experiments are performed to validate the desired properties of the proposed numerical scheme.</div></div>","PeriodicalId":8199,"journal":{"name":"Applied Numerical Mathematics","volume":"217 ","pages":"Pages 96-111"},"PeriodicalIF":2.2,"publicationDate":"2025-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144263514","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":"Analysis of a divergence-free element-free Galerkin method for the Navier-Stokes equations","authors":"Xiaolin Li , Haiyun Dong","doi":"10.1016/j.apnum.2025.06.002","DOIUrl":"10.1016/j.apnum.2025.06.002","url":null,"abstract":"<div><div>In this paper, an efficient divergence-free element-free Galerkin (DFEFG) method is proposed for the numerical analysis of the incompressible Navier-Stokes equations. In this method, a divergence-free moving least squares (DFMLS) approximation is used to obtain the meshless approximation of the divergence-free velocity field. The properties, stability and error of the DFMLS approximation are analyzed firstly, and then the stability and error estimation of the DFEFG method are derived theoretically. Finally, numerical results demonstrate the efficiency of the proposed methods and verify the theoretical analysis.</div></div>","PeriodicalId":8199,"journal":{"name":"Applied Numerical Mathematics","volume":"217 ","pages":"Pages 73-95"},"PeriodicalIF":2.2,"publicationDate":"2025-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144263513","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":"Generalized Clenshaw-Curtis quadrature method for systems of linear ODEs with constant coefficients","authors":"Fu-Rong Lin, Xi Yang, Gui-Rong Zhang","doi":"10.1016/j.apnum.2025.06.003","DOIUrl":"10.1016/j.apnum.2025.06.003","url":null,"abstract":"<div><div>In this paper, we consider high precision numerical methods for the initial problem of systems of linear ordinary differential equations (ODEs) with constant coefficients. It is well-known that the analytic solution of such a system of linear ODEs involves a matrix exponential function and an integral whose integrand is the product of a matrix exponential and a vector-valued function. We mainly consider numerical quadrature methods for the integral term in the analytic solution and propose a generalized Clenshaw-Curtis (GCC) quadrature method. The proposed method is then applied to the initial-boundary value problem for a heat conduction equation and a Riesz space fractional diffusion equation, respectively. Numerical results are presented to demonstrate the effectiveness of the proposed method.</div></div>","PeriodicalId":8199,"journal":{"name":"Applied Numerical Mathematics","volume":"217 ","pages":"Pages 112-125"},"PeriodicalIF":2.2,"publicationDate":"2025-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144272008","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":"On steepest coordinate descent method for computing extreme eigenpairs of symmetric matrices","authors":"Zhong-Zhi Bai","doi":"10.1016/j.apnum.2025.06.001","DOIUrl":"10.1016/j.apnum.2025.06.001","url":null,"abstract":"<div><div>For solving real and symmetric eigenvalue problems of huge sizes, we propose a steepest coordinate descent method, establish its convergence theory under reasonable conditions, and show its computational effectiveness by numerical experiments.</div></div>","PeriodicalId":8199,"journal":{"name":"Applied Numerical Mathematics","volume":"217 ","pages":"Pages 126-134"},"PeriodicalIF":2.2,"publicationDate":"2025-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144298735","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 new error analysis of an explicit skeletal discontinuous Galerkin scheme for time-dependent Maxwell equations","authors":"Achyuta Ranjan Dutta Mohapatra, Bhupen Deka","doi":"10.1016/j.apnum.2025.05.011","DOIUrl":"10.1016/j.apnum.2025.05.011","url":null,"abstract":"<div><div>This article focuses on the convergence analysis of second-order time-dependent Maxwell equations in conducting and non-conducting media. Firstly, the spatial discretization is made using a skeletal discontinuous Galerkin method, and then some essential tools are established to deduce the stability and error estimates. Under suitable regularity assumptions on initial data, stability and optimal convergence of the error are proved for the semi-discrete problem in a discretely defined <span><math><mi>H</mi><mtext>(curl)</mtext></math></span>-norm. Next, temporal discretization is applied to the semi-discrete system by using the explicit Leap-frog schemes and optimal error bounds <span><math><mi>O</mi><mo>(</mo><msup><mrow><mi>τ</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>+</mo><msup><mrow><mi>h</mi></mrow><mrow><mi>k</mi></mrow></msup><mo>)</mo></math></span>, <span><math><mi>k</mi><mo>≥</mo><mn>1</mn></math></span> is the degree of polynomial approximation, are achieved in the discrete energy norm. Finally, computational experiments are performed to validate the theoretical conclusions. Error analysis of explicit fully discrete schemes in polygonal/polyhedral meshes for the second-order Maxwell equations in a conducting media is missing in the literature, and we intend to fill this gap in the current article.</div></div>","PeriodicalId":8199,"journal":{"name":"Applied Numerical Mathematics","volume":"217 ","pages":"Pages 18-42"},"PeriodicalIF":2.2,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144221744","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":"Split-step θ-method for stochastic pantograph differential equations: Convergence and mean-square stability analysis","authors":"Fathalla A. Rihan, K. Udhayakumar","doi":"10.1016/j.apnum.2025.05.010","DOIUrl":"10.1016/j.apnum.2025.05.010","url":null,"abstract":"<div><div>This paper introduces a <em>split-step θ-method</em> (SS<em>θ</em>-method) with variable step sizes for solving stochastic pantograph delay differential equations (SPDDEs). We establish the mean-square convergence of the proposed SS<em>θ</em>-method and show that it achieves a strong convergence order of order 1/2. Under certain assumptions, we prove that the SS<em>θ</em>-method is exponentially mean-square stable for <span><math><mi>θ</mi><mo>≥</mo><mn>0.5</mn></math></span>. Additionally, we analyze the asymptotic mean-square stability of the SS<em>θ</em>-method under a stronger assumption. Finally, numerical examples illustrate the effectiveness of the proposed methods.</div></div>","PeriodicalId":8199,"journal":{"name":"Applied Numerical Mathematics","volume":"217 ","pages":"Pages 1-17"},"PeriodicalIF":2.2,"publicationDate":"2025-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144203865","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":"High-order numerical solution for solving multi-dimensional Schrödinger-Poisson equation","authors":"Maedeh Nemati, Mostafa Abbaszadeh, Mehdi Dehghan","doi":"10.1016/j.apnum.2025.05.004","DOIUrl":"10.1016/j.apnum.2025.05.004","url":null,"abstract":"<div><div>This paper explores the numerical solution of the Schrödinger-Poisson equation in one, two, and three dimensions, which has significant applications in quantum mechanics, cosmology, Bose-Einstein condensates, and nonlinear optics. To address the nonlinear aspects of the problem, we employ the split-step method, which decomposes the equation into linear and nonlinear components. The linear part is discretized using the compact finite difference (CFD) method, while the nonlinear component is solved exactly. For temporal discretization, we utilize the Crank-Nicolson method across all dimensions, achieving a second-order convergence rate of <span><math><mi>O</mi><mo>(</mo><msup><mrow><mi>τ</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>)</mo></math></span>. Spatial discretization is carried out using a CFD scheme, ensuring a fourth-order convergence rate of <span><math><mi>O</mi><mo>(</mo><msup><mrow><mi>h</mi></mrow><mrow><mn>4</mn></mrow></msup><mo>)</mo></math></span>. In the case of two- and three-dimensional Schrödinger equations, the alternating direction implicit (ADI) method is applied. We establish that the proposed numerical schemes are convergent, unconditionally stable, and maintain the conservation of mass and energy at the discrete level. Numerical experiments in one, two, and three dimensions validate the effectiveness of our approach. Specifically, we compare the split-step CFD scheme with alternative methods, and for higher-dimensional cases, we evaluate the ADI-split-step CFD scheme against the standard split-step CFD method. The results demonstrate that the proposed methods significantly reduce computational time while maintaining accuracy.</div></div>","PeriodicalId":8199,"journal":{"name":"Applied Numerical Mathematics","volume":"217 ","pages":"Pages 43-72"},"PeriodicalIF":2.2,"publicationDate":"2025-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144239999","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 and well-balanced scheme for the Ripa system","authors":"K.R. Arun , R. Ghorai","doi":"10.1016/j.apnum.2025.05.008","DOIUrl":"10.1016/j.apnum.2025.05.008","url":null,"abstract":"<div><div>We design and analyse an energy-stable, structure-preserving, and well-balanced scheme for the Ripa system of shallow water equations. The energy stability of the numerical solutions is achieved by introducing appropriate stabilisation terms in the discretisation of the convective fluxes of mass and momentum, the pressure gradient, and the topography source term. The careful selection of the interface values for the water height and temperature ensures the scheme's well-balancing property for three physically relevant hydrostatic steady states. The scheme, which is explicit in time and finite volume in space, preserves the positivity of both the water height and the temperature, and it is weakly consistent with the continuous model equations in the sense of Lax-Wendroff. Additionally, a suitable modification of the source term discretisation and timestep criterion allows the scheme to handle wet/dry fronts in equilibrium. The results of extensive numerical case studies on benchmark test problems confirm the theoretical findings.</div></div>","PeriodicalId":8199,"journal":{"name":"Applied Numerical Mathematics","volume":"216 ","pages":"Pages 187-209"},"PeriodicalIF":2.2,"publicationDate":"2025-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144134118","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":"High-order and mass-conservative regularized implicit-explicit relaxation Runge-Kutta methods for the low regularity Schrödinger equations","authors":"Jingye Yan , Hong Zhang , Yabing Wei , Xu Qian","doi":"10.1016/j.apnum.2025.05.009","DOIUrl":"10.1016/j.apnum.2025.05.009","url":null,"abstract":"<div><div>The non-differentiability of the singular nonlinearities (<span><math><mi>f</mi><mo>=</mo><mi>ln</mi><mo></mo><mo>|</mo><mi>u</mi><msup><mrow><mo>|</mo></mrow><mrow><mn>2</mn></mrow></msup></math></span> and <span><math><mi>f</mi><mo>=</mo><mo>|</mo><mi>u</mi><msup><mrow><mo>|</mo></mrow><mrow><mn>2</mn><mi>α</mi></mrow></msup><mo>,</mo><mspace></mspace><mi>α</mi><mo><</mo><mn>0</mn></math></span>) at <span><math><mi>u</mi><mo>=</mo><mn>0</mn></math></span> brings significant challenges in designing accurate and efficient numerical schemes for the low regularity Schrödinger equations (LorSE). In order to address the singularity, we propose an energy regularization for the LorSE. For the regularized models, we apply Implicit-explicit Relaxation Runge-Kutta methods which are linearly implicit, high order and mass-conserving for temporal discretization, in conjunction with the Fourier pseudo-spectral method in space. Ultimately, numerical results are presented to validate the efficiency of the proposed methods.</div></div>","PeriodicalId":8199,"journal":{"name":"Applied Numerical Mathematics","volume":"216 ","pages":"Pages 210-221"},"PeriodicalIF":2.2,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144139588","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}
Rui M.P. Almeida , José C.M. Duque , Jorge Ferreira , Willian S. Panni
{"title":"Numerical analysis for an evolution equation with the p-biharmonic operator","authors":"Rui M.P. Almeida , José C.M. Duque , Jorge Ferreira , Willian S. Panni","doi":"10.1016/j.apnum.2025.05.006","DOIUrl":"10.1016/j.apnum.2025.05.006","url":null,"abstract":"<div><div>In this paper, we consider a parabolic equation with the <em>p</em>-biharmonic operator, where <span><math><mi>p</mi><mo>></mo><mn>1</mn></math></span>. By employing a suitable change of variable, we transform the fourth-order nonlinear parabolic problem into a system of two second-order differential equations. We investigate the properties of the discretized solution in spatial and temporal variables. Using the Brouwer fixed point theorem we prove the existence of the discretized solution. Through classical functional analysis techniques we demonstrate the uniqueness and a priori estimates of the discretized solution. We establish the order of convergence in space and time, we establish the relationship between the temporal variable and the spatial variable, ensuring the existence of the convergence order. Additionally, we highlight that the change in variable carried out is extremely advantageous, as it allows us to obtain the order of convergence for the solution and its higher order derivatives using only lower-degree polynomials. Finally, using the finite element method with Lagrange basis, we implement the computational codes in Matlab software, considering the one and two-dimensional cases. We present three examples to illustrate and validate the theory.</div></div>","PeriodicalId":8199,"journal":{"name":"Applied Numerical Mathematics","volume":"216 ","pages":"Pages 164-186"},"PeriodicalIF":2.2,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144134117","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}