







摘要:反應-擴散方程在科學和工程的許多分支中有著重要的應用,對此類方程數值解的研究具有重要意義. 鑒于計算域的復雜形狀、大量的自由度等導致計算非常困難,提出張量積型二元三次 B 樣條法求解一 類分數階反應-擴散方程和交叉反應擴散系統,首先計算得出二元三次 B 樣條擬插值的矩陣表達式,然后利用 Matlab 進行數值模擬,最后將數值模擬解與精確解進行對比. 研究表明,當變量 t 的迭代次數較低時,所提方法行之有效.
關鍵詞:反應-擴散方程;B 樣條擬插值;張量積型;數值模擬
中圖分類號:TP391. 41 文獻標志碼:A 文章編號:1001-8395(2024)03-0411-11
doi:10. 3969 / j. issn. 1001-8395. 2024. 03. 014
對流-擴散-反應系統,包括對流-擴散和反應-擴散方程,在科學和工程的許多分支中有重要的應用 [1],這些應用包括方程模型運輸動力學 [2-4]、人口動力學 [5]、化學反應和燃燒 [6]、傳熱和傳質 [7-9]、 環境問題中濃度或污染的演變 [10]以及趨化性、模式形成和細胞生長過程 [11-15]. 因此,此類方程的準確解對于準確描述問題中的動力學和傳遞過程具有重要意義.
由于計算域的復雜形狀、相互作用的強度、大量的自由度以及所使用的數值求解器的穩定性,反應-擴散方程所涉及的相關復雜性通常會非常苛刻. Henry 等 [16]描述了用于模擬包含反常擴散的活化劑-抑制劑動態系統的雙組分反應-擴散方程;文獻[9]研究了一類反應-擴散方程的前沿動態系統.目前已經開發了許多數值方法來解決分數反應擴散問題,例如:有限差分法 [5]、有限元法 [17-18]和光譜法 [19]. 然而,由于分數階差分算子的非局部特性 [20-21],數值方案的穩定性通常變得非常敏感 [21].
此外,反應-擴散方程數值離散化通常會生成完整且密集的系數矩陣,這會導致嚴重的計算困難.然而,與反應-擴散系統不同,交叉擴散系統允許交叉擴散系數為負. 顯著的特點是反應擴散的均勻穩態是穩定的,但對于交叉擴散系統則不穩定 [22]. 例如具有自擴散和交叉擴散系統 [22-23]、非均勻反應系統 [24-25]、流行病模型 [26-27]和植被模式多樣性 [28]的捕食者-獵物模型. 交叉反應-擴散過程在自然界中質量和化學成分的傳輸中起著重要作用.這些系統包含豐富多樣的行為. 由于它們的特性, 人們對交叉反應-擴散方程的研究越來越感興趣.
通過使用有限體積方法 [29-31]、有限差分方法 [32],已經開發了一些交叉擴散模型. 然而,這些方法在處理復雜幾何形狀的傳輸時被證明具有挑戰性.本文提出二元三次 B 樣條擬插值方法解決反應-擴散方程的數值逼近問題,是一元三次 B 樣條擬插值的推廣形式,可以直接構造,不需要求解線性方程組,具有良好的保形性、計算量小等優點,它在計算幾何和數值逼近方面有著廣泛的應用 [33-34].
文獻[35-37]已證實用一維三次 B 樣條擬插值法求解 Burgers-Huxley 等偏微分方程得到的數值解與解析解非常吻合. 因此本文用二元 B 樣條擬插值法求解更為復雜的偏微分方程并考慮其精度.
本文的安排如下:第一節基于三次 B 樣條基函數的表達式,構造二元三次 B 樣條擬插值算子,并給出其張量積型的矩陣表達式;第二節分別對二元分數階反應-擴散方程和交叉反應-擴散方程的 2 個例子進行數值實驗,得到相應的數值模擬圖和數值模擬解并與其精確解進行對比分析;最后在第三節得出相應的結論.
4 結論
本文主要探討了基于二維三次 B 樣條擬插值法求解分數階反應-擴散方程和交叉反應-擴散方程的誤差,利用這種方法不需要求解線性方程組,具有計算量小、保多項式性等優點,從數值模擬的結果和相應的誤差分析可知,在迭代次數較低時,用這種方案所得到的數值解和解析解非常吻合. 數值模擬解逼近最優解,如果迭代次數較高,也即 t→∞時,運用二維 B 樣條擬插值法誤差偏大,需要進一 步探究該方法的收斂性,但是誤差在可控的范圍內,因此對于一些復雜的整數階偏微分方程可以利用此方案得到相應的數值解和數值模擬圖.
參考文獻
[1]AHMED S,LIU X F. High order integration factor methods for systems with inhomogeneous boundary conditions[J]. Journal ofComputational and Applied Mathematics,2019,348:89-102.
[2]ALZAHRANI S S,KHALIQ A Q M. Fourier spectral exponential time differencing methods for multi-dimensional space-fractionalreaction-diffusion equations[J]. Journal of Computational and Applied Mathematics,2019,361:157-175.
[3]BRATSOS A G,KHALIQ A Q M. An exponential time differencing method of lines for Burgers-Fisher and coupled Burgers equa-tions[J]. Journal of Computational and Applied Mathematics,2019,356:182-197.
[4]BURRAGE K,HALE N,KAY D. An efficient implicit FEM scheme for fractional-in-space reaction-diffusion equations[J].SIAM Journal on Scientific Computing,2012,34(4):A2145-A2172.
[5]CHEN H,L S J,CHEN W P. Finite difference / spectral approximations for the distributed order time fractional reaction diffu-sion equation on an unbounded domain[J]. Journal of Computational Physics,2016,315:84-97.
[6]CHEN S Q,ZHANG Y T. Krylov implicit integration factor methods for spatial discretization on high dimensional unstructuredmeshes:application to discontinuous Galerkin methods[J]. Journal of Computational Physics,2011,230(11):4336-4352.
[7]COLIZZA V,PASTOR-SATORRAS R,VESPIGNANI A. Reaction-diffusion processes and metapopulation models in heterogene-ous networks [J]. Nature Physics,2007,3(4):276-282.
[8]COX S M,MATTHEWS P C. Exponential time differencing for stiff systems[J]. Journal of Computational Physics,2002, 176(2):430-455.
[9]DEL-CASTILLO-NEGRETE D,CARRERAS B A ,LYNCH V E. Front dynamics in reaction-diffusion systems with Levy flights: a fractional diffusion approach[J]. Physical Review Letters,2003,91:018302.
[10]FERREIRA S C,MARTINS M L,VILELA M J. Reaction-diffusion model for the growth of avascular tumor[J]. Physical Re-view E,2002,65(2):021907.
[11]GARVIE M R. Finite-difference schemes for reaction-diffusion equations modeling predator-prey interactions in Matlab[J]. Bul-letin of Mathematical Biology,2007,69(3):931-956.
[12]GATENBY R A,GAWLINSKI E T. A reaction-diffusion model of cancer invasion[J]. Cancer Res,1996,56(24):5745-5753.
[13]GU X M,HUANG T Z,ZHAO X L,et al. Strang-type preconditioners for solving fractional diffusion equations by boundary val-ue methods[J]. Journal of Computational and Applied Mathematics,2015,277:73-86.
[14]HAJIPOUR M,JAJARMI A,BALEANU D,et al. On an accurate discretization of a variable-order fractional reaction-diffusionequation[J]. Communications in Nonlinear Science and Numerical Simulation,2019,69:119-133.
[15]HENRY B I,WEARNE S L. Fractional reaction-diffusion[J]. Physica A:Statistical Mechanics and Its Applications,2000,276(3 / 4):448-455.
[16]HENRY B I,WEARNE S L. Existence of Turing instabilities in a two-species fractional reaction-diffusion system[J]. SIAMJournal on Applied Mathematics,2002,62(3):870-887.
[17]LI M,GU X M,HUANG C M,et al. A fast linearized conservative finite element method for the strongly coupled nonlinear frac-tional Schrdinger equations[J]. Journal of Computational Physics,2018,358:256-282.
[18]LIU Y,DU Y W,LI H,et al. An H1 -Galerkin mixed finite element method for time fractional reaction-diffusion equation[J].Journal of Applied Mathematics and Computing,2015,47(1 / 2):103-117.
[19]PINDZA E,OWOLABI K M. Fourier spectral method for higher order space fractional reaction-diffusion equations[J]. Commu-nications in Nonlinear Science and Numerical Simulation,2016,40:112-128.
[20]MEERSCHAERT M M,TADJERAN C. Finite difference approximations for two-sided space-fractional partial differential equa-tions[J]. Applied Numerical Mathematics,2006,56(1):80-90.
[21]ZHANG L,SUN H W,PANG H K. Fast numerical solution for fractional diffusion equations by exponential quadrature rule[J].Comput Phys,2015,299:130-143.
[22]GUIN L N. Existence of spatial patterns in a predator-prey model with self- and cross-diffusion[J]. Applied Mathematics andComputation,2014,226:320-335.
[23]PETROVSKII S V,MALCHOW H. A minimal model of pattern formation in a prey-predator system[J]. Mathematical and Com-puter Modelling,1999,29(8):49-63.
[24]GOLOVIN A A,MATKOWSKY B J,VOLPERT V A. Turing pattern formation in the Brusselator model with superdiffusion [J].SIAM Journal on Applied Mathematics,2008,69(1):251-272.
[25]GAMBINO G,LOMBARDO M C,SAMMARTINO M. Pattern formation driven by cross-diffusion in a 2D domain[J]. NonlinearAnalysis:Real World Applications,2013,14(3):1755-1779.
[26]DIEKMANN O,KRETZSCHMAR M. Patterns in the effects of infectious diseases on population growth[J]. Journal of Mathe-matical Biology,1991,29(6):539-570.
[27]FAN Y. Pattern formation of an epidemic model with cross diffusion [J]. Applied Mathematics and Computation,2014, 228:311-319.
[28]VON HARDENBERG J,MERON E,SHACHAK M,et al. Diversity of vegetation patterns and desertification[J]. Physical Re-view Letters,2001,87(19):198101.
[29]ANDREIANOV B,BENDAHMANE M,RUIZ-BAIER R. Analysis of a finite volume method for a cross-diffusion model in popu-lation dynamics[J]. Mathematical Models and Methods in Applied Sciences,2011,21(2):307-344.
[30]RUIZ-BAIER R,TIAN C R. Mathematical analysis and numerical simulation of pattern formation under cross-diffusion[J].Nonlinear Analysis:Real World Applications,2013,14(1):601-612.
[31]LIN Z G,RUIZ-BAIER R,TIAN C R. Finite volume element approximation of an inhomogeneous Brusselator model with cross-diffusion[J]. Journal of Computational Physics,2014,256:806-823.
[32]WANG W M,LIN Y Z,ZHANG L,et al. Complex patterns in a predator-prey model with self and cross-diffusion[J]. Commu-nications in Nonlinear Science and Numerical Simulation,2011,16(4):2006-2015.
[33]王仁宏,李崇君,朱春鋼. 計算幾何教程[M]. 北京:科學出版社,2008.
[34]JIAN H Y,HUANG T Z,GU X M. Fast compact implicit integration factor method with non-uniform meshes for the two-dimen-sional nonlinear Riesz space-fractional reaction-diffusion equation[J]. Applied Numerical Mathematics,2020,156:346-363
[35]ZHU C G,WANG R H . Numerical solution of Burgers’equation by cubic B-spline quasi-Inter-polation[J]. Applied Mathemat-ics and Computation,2009,208(1):260-272.
[36]ZHU C G,KANG W S. Numerical solution of Burgers-Fisher equation by cubic B-spline quasi-interpolation[J]. Applied Mathe-matics and Computation,2010,216(9):2679-2686.
[37]SUN L Y,ZHU C G. Cubic B-spline quasi-interpolation and an application to numerical solution of generalized Burgers-Huxleyequation[J]. Advances in Mechanical Engineering,2020,12(11):1-8.
[38]齊梓萱,錢江. 對流-擴散方程數值解的四次 B 樣條方法[J]. 圖學學報,2020,41(5):716 - 724.
[39]DE BOOR C,HOLLIG K,RIEMENSCHNEIDER S. Box splines[M]. New York:Springer-Verlag,1993.
[40]SABLONNIERE P. Univariate spline quasi-interpolants and applications to numerical analysis[J]. Rendiconti del SeminarioMatematico,2005,63(3):211-222.
[41]錢江. 遞推算法與多元插值[M]. 北京:科學出版社,2020.
[42]錢江,劉雯星. 基于數值積分的最佳平方逼近樣條函數[J]. 安徽師范大學學報(自然科學版),2022,45(2):107-116.
[43]ZHANG J Y,YAN G W. Lattice Boltzmann simulation of pattern formation under cross-diffusion[J]. Computers & Mathematicswith Applications,2015,69(3):157-169
(編輯 陶志寧)