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Finite Element Method And Finite Volume Method Based On B-Spline

Posted on:2010-03-15Degree:MasterType:Thesis
Country:ChinaCandidate:D D QinFull Text:PDF
GTID:2120360272997428Subject:Computational Mathematics
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In this paper,finite element method and finite volume method based on linear B-spline and quadratic B-spline and cubic B-spline are introduccd.And precondition of linear B-spline wavelet is introduced. We achieve a variety of methods with Matlab.Let m be any positive integer and let Nm(x) denote the rath order B-spline.More precisely,Nm(x) is defined recursively bywith N1(x) =χ[0,1]-The mth order B-spline waveletwith support [0,2m-l],is a basic wavelet that generates W0,and consequently , all the wavelet spaces Wj,k∈Z([9]).We consider the two-point boundary value problem,among them ,p∈C(I),p≥0,f∈C(I),I = [a, b].Let Uh is the finite element space ,and rth B-spline function {φi(x)} is a basement of Uh .Any uh,∈Uh can be expressed as uh(x) = (?)ciφi(x).The bilinear form isGalerkin function is If r = 1,theni,j = 0,l,…,n-2. If r = 2,thcn i, j = -1,0,…,n-2. If r = 3,then i, j = -2, -1,0,…,n - 2. By ||.||1 and ||.||, finite element methods based on the rth B-spline have convergence order of O(hr) and O(hr+1).Select rth B-spline functions as the basement of the trial function space and piecewise constant functions as the basement of test function spaces.We can get integral form of conservation of (3): select u∈HE1 = {u| u∈H1(I), u(a) = 0, u(b)—0},satisfyingHere,J = [cj, dj] depends on the trial function space.Let Uh is the limited subspacc of HE1.The approximate form of (3a) : select uh,∈Uh, satisfyingFinite volume methods based on linear B-spline and cubic B-spline have same convergence order with finite element method.H1 convergence order and L2 convergenceorder based on quadratic B-spline are both O(h2).Consider (3).For the initial mesh generation Th(0) : a = x0 < X1 <…< xN,h = xi - xi-1,select linear B-spline functionΦ(0) = {φ0(0) ,φ1(0),….φN-2(0) as the basement of finite element space . Encrypt mesh generation,and let xi+(?) = xi + (?),i = 0,1,…,N - 1, Th(1) : 0 = x0 < x? < x1 <…< xN-(?) < xN = 1, finite element space in the new mesh generation isBasement of wavelet space W(0) is There is relationWe know V(1) = V(0) (?)W(0).There is the matrix L0 that meetsAΦ(0) is the stiffness matrix of finite element space V(0) ,and Aφ(0) is the coefficientmatrix after transforming basement.Then they have relation:At nth encryption ,there is the conclusion withκ(DnGnAψ(n) GnDn) = O(1).Dn is a diagonal processing matrix and Gn is the standardized matrix.The boundary wavelets satisfy...
Keywords/Search Tags:B-spline, finite element method, finite volume method, H~1-convergent order, L~2-convergent order, B-spline wavelet, condition number
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