Fractional order convection-diffusion systems show chaos under exponential cubic B-spline discretization
The dynamical behavior of nonlinear fractional convection-diffusion equations (CDEs) is very rich and extends beyond their applicability as transport models, but it has yet to be explored numerically. In this paper, it is demonstrated that a time- and space-fractional nonlinear convection-diffusion equation exhibits a transition from stable equilibrium to deterministic chaos its nonlinear convection parameter increases by employing an exponential cubic B-spline scheme for this said problem. The Caputo fractional derivative is discretized using the L1 formula, whereas the fractional spatial operators are approximated using the exponential spline method. Using phase portraits, bifurcation diagrams, and Lyapunov exponent spectra, we identify three different dynamical behaviors: a stable regime, periodic behavior, and finally chaos, arising from the increasing value of the nonlinear convection parameter. Therefore, this work establishes the nonlinear convection parameter as a true bifurcation parameter and demonstrates the possibility of complex nonlinear dynamics in fractional convection-diffusion systems.

- Tepljakov A. Fractional-Order Modeling and Control of Dynamic Systems. Springer; 2017. https://doi.org/10.1007/978-3-319-52950-9
- Jafari H, Fazli Malidareh B, Hosseini VR. Collocation discrete least squares meshless method for solving nonlinear multi-term time fractional differential equations. Eng Anal Bound Elem. 2024;158:107-120. https://doi.org/10.1016/j.enganabound.2023.10.014
- Chen W, Sun H, Li X. Fractional Derivative Modeling in Mechanics and Engineering. Springer Nature; 2022. https://doi.org/10.1007/978-981-16-8802-7
- Kulish VV, Lage JL. Application of fractional calculus to fluid mechanics. J Fluids Eng. 2002;124(3):803-806. https://doi.org/10.1115/1.1478062
- Ionescu C, Lopes A, Copot D, Machado JAT, Bates JHT. The role of fractional calculus in modeling biological phenomena: A review. Commun Nonlinear Sci Numer Simul. 2017;51:141-159. https://doi.org/10.1016/j.cnsns.2017.04.001
- D'Altri G, Mariani F, Bonafè F, et al. Dopamine-mediated analog control of electrochromic reactions through organic electrochemical transistor. Small Sci. 2026;6:e202500635. https://doi.org/10.1002/smsc.202500635
- AlBaidani MM. Mathematical analysis of fractional-order convection-reaction-diffusion equations under the Caputo fractional derivative. Front Phys. 2026;14:1762827. https://doi.org/10.3389/fphy.2026.1762827
- Mohammad M, Trounev A. A robust framework for solving PDEs: Biorthogonal spline wavelet methods. Int J Math Comput Eng. 2026;4(1):65-76. https://doi.org/10.2478/ijmce-2026-0005
- Günerhan H. Analytical and approximate solution of two-dimensional convection-diffusion problems. Int J Optim Control Theor Appl. 2020;10(1):73-77. https://doi.org/10.11121/ijocta.01.2020.00781
- Anley EF, Basha M, Hussain A, Dai B. Numerical simulation for nonlinear space-fractional reaction convection-diffusion equation with its application. Alex Eng J. 2023;65:245-261. https://doi.org/10.1016/j.aej.2022.10.047
- Rubbab Q, Nazeer M, Ahmad F, Chu YM, Khan MI, Kadry S. Numerical simulation of advection-diffusion equation with Caputo-Fabrizio time fractional derivative in cylindrical domains: Applications of pseudo-spectral collocation method. Alex Eng J. 2021;60(1):1731-1738. https://doi.org/10.1016/j.aej.2020.11.022
- Das S, Gupta PK, Ghosh P. An approximate solution of nonlinear fractional reaction-diffusion equation. Appl Math Model. 2011;35(8):4071-4076. https://doi.org/10.1016/j.apm.2011.02.004
- Zhu Y, Riera-Llobet C, Fleta C, et al. Microdosimetry maps in continuous and pulsed alpha beams. IEEE Trans Radiat Plasma Med Sci. 2026;10:799-814. https://doi.org/10.1109/TRPMS.2025.3620266
- Hillen T, Painter KJ. A user's guide to PDE models for chemotaxis. J Math Biol. 2009;58:183-217. https://doi.org/10.1007/s00285-008-0201-3
- Fang X, Lacarbonara W, Cheng L. Advances in nonlinear acoustic/elastic metamaterials and metastructures. Nonlinear Dyn. 2025;113:23787-23814. https://doi.org/10.1007/s11071-024-10219-4
- Di Gregorio L, Lacarbonara W. On bandgap sensitivity to three-to-one internal resonances between acoustic and optical waves in metamaterials. Nonlinear Dyn. 2025;113:30321-30342. https://doi.org/10.1007/s11071-025-11244-7
- Bojanov BD, Hakopian HA, Sahakian AA. Spline Functions and Multivariate Interpolations. Springer; 1993. https://doi.org/10.1007/978-94-015-8169-1
- Abbas M, Bibi A, Alzaidi ASM, Nazir T, Majeed A, Akram G. Numerical solutions of third-order time-fractional differential equations using cubic B-spline functions. Fractal Fract. 2022;6(9):528. https://doi.org/10.3390/fractalfract6090528
- Akram T, Abbas M, Ismail AI, Ali NHM, Baleanu D. Extended cubic B-splines in the numerical solution of time fractional telegraph equation. Adv Differ Equ. 2019;2019:365. https://doi.org/10.1186/s13662-019-2296-9
- Derakhshan MH, Ordokhani Y. Numerical and stability analysis of linear B-spline and local radial basis functions for solving two-dimensional distributed-order time-fractional telegraph models. J Appl Math Comput. 2025;71:2859-2887. https://doi.org/10.1007/s12190-024-02361-4
- Safdari H, Rajabzadeh M, Khalighi M. LDG approximation of a nonlinear fractional convection-diffusion equation using B-spline basis functions. Appl Numer Math. 2022;171:45-57. https://doi.org/10.1016/j.apnum.2021.08.014
- Duru K, Rannabauer L, Gabriel AA, Kreiss G, Bader M. A stable discontinuous Galerkin method for the perfectly matched layer for elastodynamics in first order form. Numer Math. 2020;146:729-782. https://doi.org/10.1007/s00211-020-01160-w
- Yousif MA, Hamasalh FK. Conformable non-polynomial spline method: A robust and accurate numerical technique. Ain Shams Eng J. 2024;15(2):102415. https://doi.org/10.1016/j.asej.2023.102415
- Yousif MA, Agarwal RP, Mohammed PO, Lupas AA, Jan R, Chorfi N. Advanced methods for conformable time-fractional differential equations: Logarithmic non-polynomial splines. Axioms. 2024;13(8):551. https://doi.org/10.3390/axioms13080551
- Yousif MA, Hamasalh FK. The fractional non-polynomial spline method: Precision and modeling improvements. Math Comput Simul. 2024;218:512-525. https://doi.org/10.1016/j.matcom.2023.11.033
- Nasir M, Jabeen S, Afzal F, Zafar A. Solving the generalized equal width wave equation via sextic B-spline collocation technique. Int J Math Comput Eng. 2023;1(2):229-242. https://doi.org/10.2478/ijmce-2023-0019
- Başhan A. A mixed methods approach to Schrödinger equation: Finite difference method and quartic B-spline based differential quadrature method. Int J Optim Control Theor Appl. 2019;9(2):223-235. https://doi.org/10.11121/ijocta.01.2019.00709
- Önal M, Karaagac B, Esen A. An efficient higher-order trigonometric cubic B-spline collocation method for time-fractional Burgers equations. Int J Math Comput Eng. 2026;4(1). https://doi.org/10.2478/ijmce-2026-0013
- Wang W, Zhang Y, Du X, Zhao G. An efficient data structure for calculation of unstructured T-spline surfaces. Vis Comput Ind Biomed Art. 2019;2:2. https://doi.org/10.1186/s42492-019-0010-0
- Peixoto JCL, Rangel RL, Martha LF. Automatic generation of T-splines with extraordinary points based on domain decomposition of quadrilateral patches. Mathematics. 2026;14(3):392. https://doi.org/10.3390/math14030392
- Sousa E. Finite Difference Methods for Fractional Diffusion Equations: One-Dimensional Time-Dependent Problems. Springer; 2026. https://doi.org/10.1007/978-3-032-11222-4
- Zhao Y, Shen C, Qu M, Bu W, Tang Y. Finite element methods for fractional diffusion equations. Int J Model Simul Sci Comput. 2020;11(4):2030001. https://doi.org/10.1142/S1793962320300010
- Yu Z, Guo S, Zhang X, Zhang B. A space-time spectral method for nonlinear fractional convection-diffusion equations with viscosity terms. Fractal Fract. 2026;10(5):324. https://doi.org/10.3390/fractalfract10050324
- Sorgentone C, Pellegrino E, Pitolli F. A spline-based framework for solving the space-time fractional convection-diffusion problem. Appl Math Lett. 2025;161:109370. https://doi.org/10.1016/j.aml.2024.109370
- Khaliq A, Mustafa I, Ibrahim TF, et al. Stability and bifurcation analysis of fifth-order nonlinear fractional difference equation. Fractal Fract. 2023;7(2):113. https://doi.org/10.3390/fractalfract7020113
- Malik S, Akbulut A, Demirbilek U, Rezazadeh H, Salahshour S. Nonlinear dynamics and bifurcation analysis of integrable models for long wave propagation in plasma physics and oceanography. Nonlinear Dyn. 2026;114:442. https://doi.org/10.1007/s11071-025-12154-4
- Ali AR, Roshid HO, Islam S, Khatun A. Analyzing bifurcation, stability, and wave solutions in nonlinear telecommunications models using transmission lines, Hamiltonian and Jacobian techniques. Sci Rep. 2024;14:15282. https://doi.org/10.1038/s41598-024-64788-w
- Sun Z, Wu X. A fully discrete difference scheme for a diffusion-wave system. Appl Numer Math. 2006;56(2):193-209. https://doi.org/10.1016/j.apnum.2005.03.003
