Pub Date : 2024-06-19DOI: 10.1016/j.apnum.2024.06.014
Saurabh Kumar , Vikas Gupta , Dia Zeidan
In this research, we propose a novel and fast computational technique for solving a class of space-time fractional-order linear and non-linear partial differential equations. Caputo-type fractional derivatives are considered. The proposed method is based on the operational and pseudo-operational matrices for the fractional-order Lagrange polynomials. To carry out the method, first, we find the integer and fractional-order operational and pseudo-operational matrix of integration. The collocation technique and obtained operational and pseudo-operational matrices are then used to generate a system of algebraic equations by reducing the given space-time fractional differential problem. The resultant algebraic system is then easily solved by Newton's iterative methods. The upper bound of the fractional-order operational matrix of integration is also provided, which confirms the convergence of fractional-order Lagrange polynomial's approximation. Finally, some numerical experiments are conducted to demonstrate the applicability and usefulness of the suggested numerical scheme.
{"title":"An efficient collocation technique based on operational matrix of fractional-order Lagrange polynomials for solving the space-time fractional-order partial differential equations","authors":"Saurabh Kumar , Vikas Gupta , Dia Zeidan","doi":"10.1016/j.apnum.2024.06.014","DOIUrl":"https://doi.org/10.1016/j.apnum.2024.06.014","url":null,"abstract":"<div><p>In this research, we propose a novel and fast computational technique for solving a class of space-time fractional-order linear and non-linear partial differential equations. Caputo-type fractional derivatives are considered. The proposed method is based on the operational and pseudo-operational matrices for the fractional-order Lagrange polynomials. To carry out the method, first, we find the integer and fractional-order operational and pseudo-operational matrix of integration. The collocation technique and obtained operational and pseudo-operational matrices are then used to generate a system of algebraic equations by reducing the given space-time fractional differential problem. The resultant algebraic system is then easily solved by Newton's iterative methods. The upper bound of the fractional-order operational matrix of integration is also provided, which confirms the convergence of fractional-order Lagrange polynomial's approximation. Finally, some numerical experiments are conducted to demonstrate the applicability and usefulness of the suggested numerical scheme.</p></div>","PeriodicalId":8199,"journal":{"name":"Applied Numerical Mathematics","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141438115","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}
Pub Date : 2024-06-18DOI: 10.1016/j.apnum.2024.06.011
Aleksandar V. Pejčev , Lothar Reichel , Miodrag M. Spalević , Stefan M. Spalević
The need to evaluate Gauss quadrature rules arises in many applications in science and engineering. It often is important to be able to estimate the quadrature error when applying an ℓ-point Gauss rule, , where f is an integrand of interest. Such an estimate often is furnished by applying another quadrature rule, , with nodes, and using the difference or its magnitude as an estimate for the quadrature error in or its magnitude. The classical approach to estimate the error in is to let , with , be the Gauss-Kronrod quadrature rule associated with . However, it is well known that the Gauss-Kronrod rule associated with a Gauss rule might not exist for certain measures that determine the Gauss rule and for certain numbers of nodes. This prompted M. M. Spalević [1] to develop generalized averaged Gauss rules, , with nodes for estimating the error in . Similarly as for -node Gauss-Kronrod rules, ℓ nodes of the rule agree with the nodes of . However, generalized averaged Gauss rules are not internal for some measures. They therefore may not be applicable when the integrand only is define
{"title":"A new class of quadrature rules for estimating the error in Gauss quadrature","authors":"Aleksandar V. Pejčev , Lothar Reichel , Miodrag M. Spalević , Stefan M. Spalević","doi":"10.1016/j.apnum.2024.06.011","DOIUrl":"https://doi.org/10.1016/j.apnum.2024.06.011","url":null,"abstract":"<div><p>The need to evaluate Gauss quadrature rules arises in many applications in science and engineering. It often is important to be able to estimate the quadrature error when applying an <em>ℓ</em>-point Gauss rule, <span><math><msub><mrow><mi>G</mi></mrow><mrow><mi>ℓ</mi></mrow></msub><mo>(</mo><mi>f</mi><mo>)</mo></math></span>, where <em>f</em> is an integrand of interest. Such an estimate often is furnished by applying another quadrature rule, <span><math><msub><mrow><mi>Q</mi></mrow><mrow><mi>k</mi></mrow></msub><mo>(</mo><mi>f</mi><mo>)</mo></math></span>, with <span><math><mi>k</mi><mo>></mo><mi>ℓ</mi></math></span> nodes, and using the difference <span><math><msub><mrow><mi>Q</mi></mrow><mrow><mi>k</mi></mrow></msub><mo>(</mo><mi>f</mi><mo>)</mo><mo>−</mo><msub><mrow><mi>G</mi></mrow><mrow><mi>ℓ</mi></mrow></msub><mo>(</mo><mi>f</mi><mo>)</mo></math></span> or its magnitude as an estimate for the quadrature error in <span><math><msub><mrow><mi>G</mi></mrow><mrow><mi>ℓ</mi></mrow></msub><mo>(</mo><mi>f</mi><mo>)</mo></math></span> or its magnitude. The classical approach to estimate the error in <span><math><msub><mrow><mi>G</mi></mrow><mrow><mi>ℓ</mi></mrow></msub><mo>(</mo><mi>f</mi><mo>)</mo></math></span> is to let <span><math><msub><mrow><mi>Q</mi></mrow><mrow><mi>k</mi></mrow></msub><mo>(</mo><mi>f</mi><mo>)</mo></math></span>, with <span><math><mi>k</mi><mo>=</mo><mn>2</mn><mi>ℓ</mi><mo>+</mo><mn>1</mn></math></span>, be the Gauss-Kronrod quadrature rule associated with <span><math><msub><mrow><mi>G</mi></mrow><mrow><mi>ℓ</mi></mrow></msub><mo>(</mo><mi>f</mi><mo>)</mo></math></span>. However, it is well known that the Gauss-Kronrod rule associated with a Gauss rule <span><math><msub><mrow><mi>G</mi></mrow><mrow><mi>ℓ</mi></mrow></msub><mo>(</mo><mi>f</mi><mo>)</mo></math></span> might not exist for certain measures that determine the Gauss rule and for certain numbers of nodes. This prompted M. M. Spalević <span>[1]</span> to develop generalized averaged Gauss rules, <span><math><msub><mrow><mover><mrow><mi>G</mi></mrow><mrow><mo>ˆ</mo></mrow></mover></mrow><mrow><mn>2</mn><mi>ℓ</mi><mo>+</mo><mn>1</mn></mrow></msub></math></span>, with <span><math><mn>2</mn><mi>ℓ</mi><mo>+</mo><mn>1</mn></math></span> nodes for estimating the error in <span><math><msub><mrow><mi>G</mi></mrow><mrow><mi>ℓ</mi></mrow></msub><mo>(</mo><mi>f</mi><mo>)</mo></math></span>. Similarly as for <span><math><mo>(</mo><mn>2</mn><mi>ℓ</mi><mo>+</mo><mn>1</mn><mo>)</mo></math></span>-node Gauss-Kronrod rules, <em>ℓ</em> nodes of the rule <span><math><msub><mrow><mover><mrow><mi>G</mi></mrow><mrow><mo>ˆ</mo></mrow></mover></mrow><mrow><mn>2</mn><mi>ℓ</mi><mo>+</mo><mn>1</mn></mrow></msub></math></span> agree with the nodes of <span><math><msub><mrow><mi>G</mi></mrow><mrow><mi>ℓ</mi></mrow></msub></math></span>. However, generalized averaged Gauss rules are not internal for some measures. They therefore may not be applicable when the integrand only is define","PeriodicalId":8199,"journal":{"name":"Applied Numerical Mathematics","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141434087","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}
Pub Date : 2024-06-17DOI: 10.1016/j.apnum.2024.06.012
Hui Yao
Numerical simulations of convective solid-liquid phase change problems have long been a complex problem due to the movement of the solid-liquid interface layer, which leads to a free boundary problem. This work develops a convective phase change heat transfer model based on the phase field method. The governing equations consist of the incompressible Navier-Stokes-Boussinesq equations, the heat transfer equation, and the Allen-Cahn equation. The Navier-Stokes equations are penalised for imposing zero velocity within the solid region. For numerical methods, the mini finite element approach (P1b-P1) is used to solve the momentum equation spatially, the temperature and the phase field are approximated by the P1b elements. In the temporal discretization, the phase field and the temperature are decoupled from the momentum equation by using the finite difference method, forming a solvable linear system. A maximum bound principle for the phase field is derived, coming with an estimation of the tolerance of the time step size, which depends on the temperature range. This estimation guides the time step choice in the simulation. The program is developed within the FreeFem++ framework, drawing on our previous work on phase field methods [1] and a mushy-region method toolbox for heat transfer [2]. The accuracy and effectiveness of the proposed method have been validated through real-world cases of melting and solidification with linear or nonlinear buyangcy force, respectively. The simulation results are in agreement with experiments in references.
{"title":"A phase field method for convective phase change problem preserving maximum bound principle","authors":"Hui Yao","doi":"10.1016/j.apnum.2024.06.012","DOIUrl":"https://doi.org/10.1016/j.apnum.2024.06.012","url":null,"abstract":"<div><p>Numerical simulations of convective solid-liquid phase change problems have long been a complex problem due to the movement of the solid-liquid interface layer, which leads to a free boundary problem. This work develops a convective phase change heat transfer model based on the phase field method. The governing equations consist of the incompressible Navier-Stokes-Boussinesq equations, the heat transfer equation, and the Allen-Cahn equation. The Navier-Stokes equations are penalised for imposing zero velocity within the solid region. For numerical methods, the mini finite element approach (<span>P1b-P1</span>) is used to solve the momentum equation spatially, the temperature and the phase field are approximated by the <span>P1b</span> elements. In the temporal discretization, the phase field and the temperature are decoupled from the momentum equation by using the finite difference method, forming a solvable linear system. A maximum bound principle for the phase field is derived, coming with an estimation of the tolerance of the time step size, which depends on the temperature range. This estimation guides the time step choice in the simulation. The program is developed within the <span>FreeFem++</span> framework, drawing on our previous work on phase field methods <span>[1]</span> and a mushy-region method toolbox for heat transfer <span>[2]</span>. The accuracy and effectiveness of the proposed method have been validated through real-world cases of melting and solidification with linear or nonlinear buyangcy force, respectively. The simulation results are in agreement with experiments in references.</p></div>","PeriodicalId":8199,"journal":{"name":"Applied Numerical Mathematics","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0168927424001582/pdfft?md5=2072fce0ac49fb6e14195fb698625ef4&pid=1-s2.0-S0168927424001582-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141434086","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-14DOI: 10.1016/j.apnum.2024.06.015
Aws Mushtaq Mudheher, S. Pishbin, P. Darania, Shadi Malek Bagomghaleh
In the present study, we construct a considerably fast convergent multistep collocation technique in order to solve Volterra integral equations, especially first-kind ones with variable vanishing delays. Through a robust theoretical analysis, the optimal global convergence of the numerically achieved solutions to their exact counterparts has been demonstrated with the corresponding high orders. The allusion to the strategy of reformulating a first-kind Volterra integral equation into a second-kind Volterra functional integral equation, assists us for the establishment of regularity, existence and uniqueness features of analytical solution over under consideration equation. The existence and uniqueness of numerical solution have also been shown. Eventually, some test problems have been provided to evaluate effectiveness of the proposed multistep collocation technique.
{"title":"High-rate convergent multistep collocation techniques to a first-kind Volterra integral equation along with the proportional vanishing delay","authors":"Aws Mushtaq Mudheher, S. Pishbin, P. Darania, Shadi Malek Bagomghaleh","doi":"10.1016/j.apnum.2024.06.015","DOIUrl":"10.1016/j.apnum.2024.06.015","url":null,"abstract":"<div><p>In the present study, we construct a considerably fast convergent multistep collocation technique in order to solve Volterra integral equations, especially first-kind ones with variable vanishing delays. Through a robust theoretical analysis, the optimal global convergence of the numerically achieved solutions to their exact counterparts has been demonstrated with the corresponding high orders. The allusion to the strategy of reformulating a first-kind Volterra integral equation into a second-kind Volterra functional integral equation, assists us for the establishment of regularity, existence and uniqueness features of analytical solution over under consideration equation. The existence and uniqueness of numerical solution have also been shown. Eventually, some test problems have been provided to evaluate effectiveness of the proposed multistep collocation technique.</p></div>","PeriodicalId":8199,"journal":{"name":"Applied Numerical Mathematics","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141405620","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}
Pub Date : 2024-06-14DOI: 10.1016/j.apnum.2024.06.013
Mufutau Ajani Rufai , Bruno Carpentieri , Higinio Ramos
This paper proposes a new pair of block techniques (NPBT) for the direct solution of third-order singular initial-value problems (IVPs). The proposed method uses a polynomial and two intermediate points to approximate the theoretical solution of third-order singular IVPs, resulting in a reasonable approximation within the integration interval. The method's essential features, including stability and convergence order, are analyzed. The proposed NPBT method is improved by using an embedding-like strategy that allows it to be executed in a variable step size mode in order to gain better efficiency. The effectiveness of the proposed method is assessed using various model problems. The approximate solution provided by the proposed NPBT method is more accurate than that of the existing methods utilized for comparison. This efficient solution positions NPBT as a good numerical method for integrating third-order singular IVP models in the fields of applied sciences and engineering.
{"title":"A new pair of block techniques for direct integration of third-order singular IVPs","authors":"Mufutau Ajani Rufai , Bruno Carpentieri , Higinio Ramos","doi":"10.1016/j.apnum.2024.06.013","DOIUrl":"10.1016/j.apnum.2024.06.013","url":null,"abstract":"<div><p>This paper proposes a new pair of block techniques (NPBT) for the direct solution of third-order singular initial-value problems (IVPs). The proposed method uses a polynomial and two intermediate points to approximate the theoretical solution of third-order singular IVPs, resulting in a reasonable approximation within the integration interval. The method's essential features, including stability and convergence order, are analyzed. The proposed NPBT method is improved by using an embedding-like strategy that allows it to be executed in a variable step size mode in order to gain better efficiency. The effectiveness of the proposed method is assessed using various model problems. The approximate solution provided by the proposed NPBT method is more accurate than that of the existing methods utilized for comparison. This efficient solution positions NPBT as a good numerical method for integrating third-order singular IVP models in the fields of applied sciences and engineering.</p></div>","PeriodicalId":8199,"journal":{"name":"Applied Numerical Mathematics","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141404343","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}
Pub Date : 2024-06-13DOI: 10.1016/j.apnum.2024.06.010
Wenli Wang , Gangrong Qu , Caiqin Song , Youran Ge , Yuhan Liu
Image restoration is a large-scale discrete ill-posed problem, which can be transformed into a Tikhonov regularization problem that can approximate the original image. Kronecker product approximation is introduced into the Tikhonov regularization problem to produce an alternative problem of solving the generalized Sylvester matrix equation, reducing the scale of the image restoration problem. This paper considers solving this alternative problem by applying the conjugate gradient least squares (CGLS) method which has been demonstrated to be efficient and concise. The convergence of the CGLS method is analyzed, and it is demonstrated that the CGLS method converges to the least squares solution within the finite number of iteration steps. The effectiveness and superiority of the CGLS method are verified by numerical tests.
{"title":"Tikhonov regularization with conjugate gradient least squares method for large-scale discrete ill-posed problem in image restoration","authors":"Wenli Wang , Gangrong Qu , Caiqin Song , Youran Ge , Yuhan Liu","doi":"10.1016/j.apnum.2024.06.010","DOIUrl":"10.1016/j.apnum.2024.06.010","url":null,"abstract":"<div><p>Image restoration is a large-scale discrete ill-posed problem, which can be transformed into a Tikhonov regularization problem that can approximate the original image. Kronecker product approximation is introduced into the Tikhonov regularization problem to produce an alternative problem of solving the generalized Sylvester matrix equation, reducing the scale of the image restoration problem. This paper considers solving this alternative problem by applying the conjugate gradient least squares (CGLS) method which has been demonstrated to be efficient and concise. The convergence of the CGLS method is analyzed, and it is demonstrated that the CGLS method converges to the least squares solution within the finite number of iteration steps. The effectiveness and superiority of the CGLS method are verified by numerical tests.</p></div>","PeriodicalId":8199,"journal":{"name":"Applied Numerical Mathematics","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141398286","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}
Pub Date : 2024-06-12DOI: 10.1016/j.apnum.2024.06.008
Arvet Pedas, Mikk Vikerpuur
We study the smoothness properties of solutions to nonlinear Volterra integral equations of the second kind on a bounded interval . The kernel of the integral operator of the underlying equation may have a diagonal singularity and a boundary singularity. Information about them is given through certain estimates. To characterize the regularity of solutions of such equations we show that the solution belongs to an appropriately weighted space of smooth functions on , with possible singularities of the derivatives of the solution at the left endpoint of the interval .
{"title":"On the regularity of solutions to a class of nonlinear Volterra integral equations with singularities","authors":"Arvet Pedas, Mikk Vikerpuur","doi":"10.1016/j.apnum.2024.06.008","DOIUrl":"10.1016/j.apnum.2024.06.008","url":null,"abstract":"<div><p>We study the smoothness properties of solutions to nonlinear Volterra integral equations of the second kind on a bounded interval <span><math><mo>[</mo><mn>0</mn><mo>,</mo><mi>b</mi><mo>]</mo></math></span>. The kernel of the integral operator of the underlying equation may have a diagonal singularity and a boundary singularity. Information about them is given through certain estimates. To characterize the regularity of solutions of such equations we show that the solution belongs to an appropriately weighted space of smooth functions on <span><math><mo>(</mo><mn>0</mn><mo>,</mo><mi>b</mi><mo>]</mo></math></span>, with possible singularities of the derivatives of the solution at the left endpoint of the interval <span><math><mo>[</mo><mn>0</mn><mo>,</mo><mi>b</mi><mo>]</mo></math></span>.</p></div>","PeriodicalId":8199,"journal":{"name":"Applied Numerical Mathematics","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141394239","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}
Pub Date : 2024-06-12DOI: 10.1016/j.apnum.2024.06.009
Suayip Toprakseven , Natesan Srinivasan
In this article, we study the weak Galerkin finite element method to solve a class of a third order singularly perturbed convection-diffusion differential equations. Using some knowledge on the exact solution, we prove a robust uniform convergence of order on the layer-adapted meshes including Bakhvalov-Shishkin type, and Bakhvalov-type and almost optimal uniform error estimates of order on Shishkin-type mesh with respect to the perturbation parameter in the energy norm using high-order piecewise discontinuous polynomials of degree k. Here N is the number mesh intervals. We conduct numerical examples to support our theoretical results.
{"title":"An efficient weak Galerkin FEM for third-order singularly perturbed convection-diffusion differential equations on layer-adapted meshes","authors":"Suayip Toprakseven , Natesan Srinivasan","doi":"10.1016/j.apnum.2024.06.009","DOIUrl":"10.1016/j.apnum.2024.06.009","url":null,"abstract":"<div><p>In this article, we study the weak Galerkin finite element method to solve a class of a third order singularly perturbed convection-diffusion differential equations. Using some knowledge on the exact solution, we prove a robust uniform convergence of order <span><math><mi>O</mi><mo>(</mo><msup><mrow><mi>N</mi></mrow><mrow><mo>−</mo><mo>(</mo><mi>k</mi><mo>−</mo><mn>1</mn><mo>/</mo><mn>2</mn><mo>)</mo></mrow></msup><mo>)</mo></math></span> on the layer-adapted meshes including Bakhvalov-Shishkin type, and Bakhvalov-type and almost optimal uniform error estimates of order <span><math><mi>O</mi><mo>(</mo><msup><mrow><mo>(</mo><msup><mrow><mi>N</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup><mi>ln</mi><mo></mo><mi>N</mi><mo>)</mo></mrow><mrow><mo>(</mo><mi>k</mi><mo>−</mo><mn>1</mn><mo>/</mo><mn>2</mn><mo>)</mo></mrow></msup><mo>)</mo></math></span> on Shishkin-type mesh with respect to the perturbation parameter in the energy norm using high-order piecewise discontinuous polynomials of degree <em>k</em>. Here <em>N</em> is the number mesh intervals. We conduct numerical examples to support our theoretical results.</p></div>","PeriodicalId":8199,"journal":{"name":"Applied Numerical Mathematics","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141392184","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}
Pub Date : 2024-06-10DOI: 10.1016/j.apnum.2024.06.004
Linshuang He , Jun Guo , Minfu Feng
In this paper, we develop two discontinuous Galerkin (DG) finite element methods to solve the linear poroelasticity in the total pressure formulation, where displacement, fluid pressure, and total pressure are unknowns. The fully-discrete standard DG and conforming DG methods are presented based on the discontinuous approximations in space and the implicit Euler discretization in time. Compared to the standard DG method with penalty terms, the conforming DG method removes all stabilizers and maintains conforming finite element formulation by utilizing weak operators defined over discontinuous functions. The two methods provide locally conservative solutions and achieve locking-free properties in poroelasticity. We also derive the well-posedness and optimal a priori error estimates, which show that our methods satisfy parameter-robustness with respect to the infinitely large Lamé constant and the null-constrained specific storage coefficient. Several numerical experiments are performed to verify these theoretical results, even in heterogeneous porous media.
{"title":"Analysis of two discontinuous Galerkin finite element methods for the total pressure formulation of linear poroelasticity model","authors":"Linshuang He , Jun Guo , Minfu Feng","doi":"10.1016/j.apnum.2024.06.004","DOIUrl":"https://doi.org/10.1016/j.apnum.2024.06.004","url":null,"abstract":"<div><p>In this paper, we develop two discontinuous Galerkin (DG) finite element methods to solve the linear poroelasticity in the total pressure formulation, where displacement, fluid pressure, and total pressure are unknowns. The fully-discrete standard DG and conforming DG methods are presented based on the discontinuous approximations in space and the implicit Euler discretization in time. Compared to the standard DG method with penalty terms, the conforming DG method removes all stabilizers and maintains conforming finite element formulation by utilizing weak operators defined over discontinuous functions. The two methods provide locally conservative solutions and achieve locking-free properties in poroelasticity. We also derive the well-posedness and optimal <em>a priori</em> error estimates, which show that our methods satisfy parameter-robustness with respect to the infinitely large Lamé constant and the null-constrained specific storage coefficient. Several numerical experiments are performed to verify these theoretical results, even in heterogeneous porous media.</p></div>","PeriodicalId":8199,"journal":{"name":"Applied Numerical Mathematics","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141322524","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}
Pub Date : 2024-06-10DOI: 10.1016/j.apnum.2024.05.026
Muhammad Usman , Muhammad Hamid , Dianchen Lu , Zhengdi Zhang
The behavior of nonlinear dynamical systems arising in mathematical physics through numerical tools is a challenging task for researchers. In this context, an efficient semi-spectral method is proposed and applied to observe the robust solutions for the mathematical physics problems. Firstly, the space variable is approximated by the Vieta-Lucas polynomials and then the s-stage one-step method is applied to discretize the temporal variable which transfers the problem in the form . Novel operational matrices of integer order are developed to replace the spatial derivative terms presented in the discussed problem. Related theorems are included in the study to validate the approach mathematically. The proposed semi-spectral schemes convert the considered nonlinear problem to a system of linear algebraic equations which is easier to tackle. We also accomplish an investigation on the error bound and convergence to confirm the mathematical formulation of the computational algorithm. To show the accuracy and effectiveness of the suggested computational method numerous test problems, such as the advection-diffusion problem, generalized Burger-Huxley, sine-Gordon, and modified KdV–Burgers’ equations are considered. An inclusive comparative examination demonstrates the currently suggested computational method in terms of credibility, accuracy, and reliability. Moreover, the coupling of the spectral method with the fourth-order Runge-Kutta method seems outstanding to handle the nonlinear problem to examine the precise smooth and non-smooth solutions of physical problems. The computational order of convergence (COC) is computed numerically through numerous simulations of the proposed schemes. It is found that the proposed schemes are in exponential order of convergence in the spatial direction and the COC in the temporal direction validates the studies in the literature.
{"title":"Innovative coupling of s-stage one-step and spectral methods for non-smooth solutions of nonlinear problems","authors":"Muhammad Usman , Muhammad Hamid , Dianchen Lu , Zhengdi Zhang","doi":"10.1016/j.apnum.2024.05.026","DOIUrl":"10.1016/j.apnum.2024.05.026","url":null,"abstract":"<div><p>The behavior of nonlinear dynamical systems arising in mathematical physics through numerical tools is a challenging task for researchers. In this context, an efficient semi-spectral method is proposed and applied to observe the robust solutions for the mathematical physics problems. Firstly, the space variable is approximated by the Vieta-Lucas polynomials and then the <em>s</em>-stage one-step method is applied to discretize the temporal variable which transfers the problem in the form <span><math><mrow><msup><mrow><mi>C</mi></mrow><mrow><mi>n</mi><mo>+</mo><mn>1</mn></mrow></msup><mo>=</mo><msup><mrow><mi>C</mi></mrow><mi>n</mi></msup><mo>+</mo><mstyle><mi>Δ</mi></mstyle><mi>t</mi><mi>ϕ</mi><mrow><mo>(</mo><mrow><mi>x</mi><mo>,</mo><mi>t</mi><mo>,</mo><msup><mrow><mi>C</mi></mrow><mi>n</mi></msup><mo>,</mo><mi>F</mi><mrow><mo>(</mo><msup><mrow><mi>u</mi></mrow><mi>n</mi></msup><mo>)</mo></mrow></mrow><mo>)</mo></mrow></mrow></math></span>. Novel operational matrices of integer order are developed to replace the spatial derivative terms presented in the discussed problem. Related theorems are included in the study to validate the approach mathematically. The proposed semi-spectral schemes convert the considered nonlinear problem to a system of linear algebraic equations which is easier to tackle. We also accomplish an investigation on the error bound and convergence to confirm the mathematical formulation of the computational algorithm. To show the accuracy and effectiveness of the suggested computational method numerous test problems, such as the advection-diffusion problem, generalized Burger-Huxley, sine-Gordon, and modified KdV–Burgers’ equations are considered. An inclusive comparative examination demonstrates the currently suggested computational method in terms of credibility, accuracy, and reliability. Moreover, the coupling of the spectral method with the fourth-order Runge-Kutta method seems outstanding to handle the nonlinear problem to examine the precise smooth and non-smooth solutions of physical problems. The computational order of convergence (COC) is computed numerically through numerous simulations of the proposed schemes. It is found that the proposed schemes are in exponential order of convergence in the spatial direction and the COC in the temporal direction validates the studies in the literature.</p></div>","PeriodicalId":8199,"journal":{"name":"Applied Numerical Mathematics","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141395881","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}