Abstract
An inverse source problem for a non-automonous time fractional diffusion equation of order \((0<\beta <1)\) is considered in a bounded Lipschitz domain in \(\mathbb {R}^d\). The missing solely time-dependent source is recovered from an additional integral measurement. The existence, uniqueness and regularity of a weak solution is studied. We design two numerical algorithms based on Rothe’s method over uniform and graded grids, derive a priori estimates and prove convergence of iterates towards the exact solution. An essential feature of the fractional subdiffusion problem is that the solution lacks the smoothness near the initial time, although it would be smooth away from \(t = 0\). Rothe’s method on a uniform grid addresses the existence of a such a solution (non-smooth with \(t^\gamma \) term where \(1>\gamma > \beta \)) under low regularity assumptions, whilst Rothe’s method over graded grids has the advantage to cope better with the behaviour at \(t=0\) (also here \(t^\beta \) is included in the class of admissible solutions) for the considered problems. The theoretical obtained results are supported by numerical experiments and stay valid in case of smooth solutions to the problem.
Similar content being viewed by others
Data Availability Statement
Data sharing is not applicable to this article as no datasets were generated or analysed during the current study.
Code Availability Statement
The authors used the open-source computing platform FEniCS for computations.
References
Alnæs, M.S., Blechta, J., Hake, J., Johansson, A., Kehlet, B., Logg, A., Richardson, C., Ring, J., Rognes, M.E., Wells, G.N.: The FEniCS project version 1.5. Arch. Numer. Softw. 3(100), 9–23 (2015)
Bainov, D., Simeonov, P.: Integral inequalities and applications. In: Mathematics and Its Applications. East European Series. Kluwer Academic Publishers, Dordrecht (1992)
Brunner, H.: The numerical solution of weakly singular volterra integral equations by collocation on graded meshes. Math. Comput. 45(172), 417–437 (1985)
Brunner, H., Ling, L., Yamamoto, M.: Numerical simulations of 2d fractional subdiffusion problems. J. Comput. Phys. 229(18), 6613–6622 (2010)
Cannon, J.R., Esteva, S.P., Van Der Hoek, J.: A galerkin procedure for the diffusion equation subject to the specification of mass. SIAM J. Numer. Anal. 24(3), 499–515 (1987)
Ismailov, M.I., Çiçek, M.: Inverse source problem for a time-fractional diffusion equation with nonlocal boundary conditions. Appl. Math. Model. 40(7), 4891–4899 (2016)
Jiang, D., Liu, Y., Wang, D.: Numerical reconstruction of the spatial component in the source term of a time-fractional diffusion equation. Adv. Comput. Math. 46(3), 43 (2020)
Jin, B., Lazarov, R., Zhou, Z.: An analysis of the L1 scheme for the subdiffusion equation with nonsmooth data. IMA J. Numer. Anal. 36(1), 197–221 (2016)
Jin, B., Li, B., Zhou, Z.: Numerical analysis of nonlinear subdiffusion equations. SIAM J. Numer. Anal. 56(1), 1–23 (2018)
Jin, B., Rundell, W.: A tutorial on inverse problems for anomalous diffusion processes. Inverse Probl. 31(3), 035003 (2015)
Kačur, J.: Method of rothe in evolution equations. In: Equadiff, pp. 23–34. Springer, New York (1986)
Karimi, M., Moradlou, F., Hajipour, M.: On regularization and error estimates for the backward heat conduction problem with time-dependent thermal diffusivity factor. Commun. Nonlinear Sci. Numer. Simul. 63, 21–37 (2018)
Karimi, M., Moradlou, F., Hajipour, M.: Regularization technique for an inverse space-fractional backward heat conduction problem. J. Sci. Comput. 83(2), 37 (2020)
Karimi, M., Moradlou, F., Hajipour, M.: On the ill-posed analytic continuation problem: an order optimal regularization scheme. Appl. Numer. Math. 161, 311–332 (2021)
Karimi, M., Zallani, F., Sayevand, K.: Wavelet regularization strategy for the fractional inverse diffusion problem. Numer Algorithms (2020)
Kazem, S.: Exact solution of some linear fractional differential equations by Laplace transform. Int. J. Nonlinear Sci. 16(1), 3–11 (2013)
Kirane, M., Malik, S.A., Al-Gwaiz, M.A.: An inverse source problem for a two dimensional time fractional diffusion equation with nonlocal boundary conditions. Math. Methods Appl. Sci. 36(9), 1056–1069 (2013)
Kopteva, N.: Error analysis of the \(L1\) method on graded and uniform meshes for a fractional-derivative problem in two and three dimensions. Math. Comput. 88(319), 2135–2155 (2019)
Kubica, A., Yamamoto, M.: Initial-boundary value problems for fractional diffusion equations with time-dependent coefficients. Fract. Calc. Appl. Anal. 21(2), 276–311 (2018)
Kufner, A., John, O., Fučík, S.: Function spaces. In: Monographs and Textbooks on Mechanics of Solids and Fluids. Noordhoff International Publishing, Leyden (1977)
Li, Y.S., Sun, L.L., Zhang, Z.Q., Wei, T.: Identification of the time-dependent source term in a multi-term time-fractional diffusion equation. Numer, Algorithms 82(4), 1279–1301 (2019)
Liao, Hl., Li, D., Zhang, J.: Sharp error estimate of the nonuniform l1 formula for linear reaction-subdiffusion equations. SIAM J. Numer. Anal. 56(2), 1112–1133 (2018)
Lin, Y., Xu, C.: Finite difference/spectral approximations for the time-fractional diffusion equation. J. Comput. Phys. 225(2), 1533–1552 (2007)
Logg, A., Mardal, K.A., Wells, G.N., et al.: Automated Solution of Differential Equations by the Finite Element Method. Springer, Berlin, Heidelberg (2012)
Logg, A., Wells, G.N.: DOLFIN: automated finite element computing. ACM Trans. Math. Softw. 37(2), 28 (2010)
Logg, A., Wells, G.N., Hake, J.: DOLFIN: a C++/Python Finite Element Library, chap. 10. Springer, Berlin, Heidelberg (2012)
Luchko, Y.: Initial-boundary-value problems for the one-dimensional time-fractional diffusion equation. Fract. Calc. Appl. Anal. 15(1), 141–160 (2012)
McLean, W.: Regularity of solutions to a time-fractional diffusion equation. ANZIAM J. 52(2), 123–138 (2010)
Metzler, R., Klafter, J.: The random walk’s guide to anomalous diffusion: a fractional dynamics approach. Phys. Rep. 339(1), 1–77 (2000)
Mustapha, K.: An implicit finite-difference time-stepping method for a sub-diffusion equation, with spatial discretization by finite elements. IMA J. Numer. Anal. 31(2), 719–739 (2011)
Mustapha, K., AlMutawa, J.: A finite difference method for an anomalous sub-diffusion equation, theory and applications. Numer. Algorithms 61(4), 525–543 (2012)
Mustapha, K., McLean, W.: Superconvergence of a discontinuous galerkin method for fractional diffusion and wave equations. SIAM J. Numer. Anal. 51(1), 491–515 (2013)
Nohel, J.A., Shea, D.F.: Frequency domain methods for Volterra equations. Adv. Math. 22(3), 278–304 (1976)
Rektorys, K.: The method of discretization in time and partial differential equations. Equadiff 5, 293–296 (1982)
Roussy, G., Bennani, A., Thiebaut, J.M.: Temperature runaway of microwave irradiated materials. J. Appl. Phys. 62(4), 1167–1170 (1987)
Sakamoto, K., Yamamoto, M.: Initial value/boundary value problems for fractional diffusion-wave equations and applications to some inverse problems. J. Math. Anal. Appl. 382(1), 426–447 (2011)
Sakamoto, K., Yamamoto, M.: Inverse source problem with a final overdetermination for a fractional diffusion equation. Math. Control Relat. Fields 1(4), 509–518 (2011)
Slodička, M., Šišková, K.: An inverse source problem in a semilinear time-fractional diffusion equation. Comput. Math. Appl. 72(6), 1655–1669 (2016)
Slodička, M.: Numerical solution of a parabolic equation with a weakly singular positive-type memory term. Electron. J. Differ. Equ. 1997, paper 9, 12 (1997)
Slodička, M., Šišková, K., Van Bockstal, K.: Uniqueness for an inverse source problem of determining a space dependent source in a time-fractional diffusion equation. Appl. Math. Lett. 91, 15–21 (2019)
Srivastava, H.M., Daoust, M.C.: A note on the convergence of Kampé de Fériet’s double hypergeometrics series. Math. Nachr. 53, 151–159 (1972). https://doi.org/10.1002/mana.19720530114
Stynes, M., O’Riordan, E., Gracia, J.L.: Error analysis of a finite difference method on graded meshes for a time-fractional diffusion equation. SIAM J. Numer. Anal. 55(2), 1057–1079 (2017)
Sun, Zz., Wu, X.: A fully discrete difference scheme for a diffusion-wave system. Appl. Numer. Math. 56(2), 193–209 (2006)
Van Bockstal, K.: Existence and uniqueness of a weak solution to a non-autonomous time-fractional diffusion equation (of distributed order). Appl. Math. Lett. 109, 106540 (2020)
Van Bockstal, K.: Existence of a unique weak solution to a nonlinear non-autonomous time-fractional wave equation (of distributed-order). Mathematics 8(8), 1283 (2020)
Vladimirov, V.S.: Equations of mathematical physics. (Uravneniya matematicheskoj fiziki.) 2. überarb. und erg. Auflage. Moskau: Verlag ”Nauka”, Hauptredaktion für physikalisch-mathematische Literatur. 512 S. R. 1.05 (1971). (1971)
Wahba, G.: Spline Models for Observational Data. Society for Industrial and Applied Mathematics, Philadelphia (1990)
Wang, J.G., Zhou, Y.B., Wei, T.: Two regularization methods to identify a space-dependent source for the time-fractional diffusion equation. Appl. Numer. Math. 68, 39–57 (2013)
Wei, T., Wang, J.: A modified quasi-boundary value method for an inverse source problem of the time-fractional diffusion equation. Appl. Numer. Math. 78, 95–111 (2014)
Wei, T., Zhang, Z.: Reconstruction of a time-dependent source term in a time-fractional diffusion equation. Eng. Anal. Boundary Elem. 37(1), 23–31 (2013)
Yang, F., Liu, X., Li, X.X.: Landweber iterative regularization method for identifying the unknown source of the modified Helmholtz equation. Boundary Value Probl. 2017(1), 91 (2017)
Yeganeh, S., Mokhtari, R., Hesthaven, J.S.: Space-dependent source determination in a time-fractional diffusion equation using a local discontinuous Galerkin method. BIT 57(3), 685–707 (2017)
Zaky, M.A., Hendy, A.S., Macías-Díaz, J.E.: Semi-implicit galerkin-legendre spectral schemes for nonlinear time-space fractional diffusion-reaction equations with smooth and nonsmooth solutions. J. Sci. Comput. 82(1), 1–27 (2020)
Zhang, M., Liu, J.: Identification of a time-dependent source term in a distributed-order time-fractional equation from a nonlocal integral observation. Comput. Math. Appl. 78(10), 3375–3389 (2019)
Acknowledgements
The authors are grateful to the handling editor and the anonymous referees for their constructive feedback and helpful suggestions, which highly improved the paper. The authors would also like to thank Professor Vladimir G. Pimenov of Ural Federal University and Professor Marián Slodička of Ghent University, for their generosity and guidance, which has always been so valuable to them.
Author information
Authors and Affiliations
Corresponding author
Ethics declarations
Funding
A. S. Hendy wishes to acknowledge the support of the RSF grant, project 22-21-00075. K. Van Bockstal is supported by a postdoctoral fellowship of the Research Foundation - Flanders (106016/12P2919N).
Conflicts of interest/Competing interests
The authors have no conflicts of interest to declare that are relevant to the content of this article.
Additional information
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
About this article
Cite this article
Hendy, A.S., Van Bockstal, K. On a Reconstruction of a Solely Time-Dependent Source in a Time-Fractional Diffusion Equation with Non-smooth Solutions. J Sci Comput 90, 41 (2022). https://doi.org/10.1007/s10915-021-01704-8
Received:
Revised:
Accepted:
Published:
DOI: https://doi.org/10.1007/s10915-021-01704-8
Keywords
- Inverse source problem
- Reconstruction
- Fractional diffusion
- Uniform and nonuniform (graded) meshes
- Prior estimates
- Convergence