On Stability of a Third Order of Accuracy Difference Scheme for Hyperbolic Nonlocal BVP with Self-Adjoint Operator
Abstract
A third order of accuracy absolutely stable difference schemes is presented for nonlocal boundary value hyperbolic problem of the differential equations in a Hilbert space H with self-adjoint positive definite operator A. Stability estimates for solution of the difference scheme are established. In practice, one-dimensional hyperbolic equation with nonlocal boundary conditions is considered.
1. Introduction
In modeling several phenomena of physics, biology, and ecology mathematically, there often arise problems with nonlocal boundary conditions (see [1–5] and the references given therein). Nonlocal boundary value problems have been a major research area in the case when it is impossible to determine the boundary conditions of the unknown function. Over the last few decades, the study of nonlocal boundary value problems is of substantial contemporary interest (see, e.g., [6–14] and the references given therein).
- (i)
u(t) is twice continuously differentiable on the segment [0,1]. The derivatives at the endpoints of the segment are understood as the appropriate unilateral derivatives.
- (ii)
The element u(t) belongs to D(A) for all t ∈ [0,1] and the function Au(t) is continuous on the segment [0,1].
- (iii)
u(t) satisfies the equations and the nonlocal boundary conditions (1).
Here, φ(x), ψ(x) (x ∈ [0,1]) and f(t, x) (t, x ∈ [0,1]) are smooth functions.
In the study of numerical methods for solving PDEs, stability is an important research area (see [6–27]). Many scientists work on difference schemes for hyperbolic partial differential equations, in which stability was established under the assumption that the magnitudes of the grid steps τ and h with respect to the time and space variables are connected. This particularly means that τ∥Ah∥ → 0 when τ → 0.
We are interested in studying high order of accuracy unconditionally stable difference schemes for hyperbolic PDEs.
In the present paper, third order of accuracy difference scheme generated by integer power of A for approximately solving nonlocal boundary value problem (1) is presented. The stability estimates for solution of the difference scheme are established.
In [8], some results of this paper, without proof, were presented.
The well posedness of nonlocal boundary value problems for parabolic equations, elliptic equations, and equations of mixed types have been studied extensively by many scientists (see, e.g., [11–14, 19–32] and the references therein).
2. Third Order of Accuracy Difference Scheme Subject to Nonlocal Conditions
Lemma 1. The following estimates hold:
Now let us give, without proof, the second lemma.
Lemma 2. The following estimates hold:
Lemma 3. Suppose that assumption (4) holds. Then, the operator I − Bτ has an inverse . From symmetry and positivity properties of operator A, the following estimate is satisfied:
Proof. Using the definitions of , estimates (11), and the following simple estimates,
So, formulas (19) and (23) give a solution of problem (2).
Theorem 4. Suppose that assumption (4) holds and φ ∈ D(A3/2), ψ ∈ D(A1/2). Then, for solution of difference scheme (2), the following stability estimates hold:
Proof. Using formulas in (23) and estimates (11), (12), and (14), we obtain
Applying A1/2 to formulas in (23), we get
Next, let us obtain the estimates for and . First, applying A to formula (28) and using estimates (11), (12), and (14) and the triangle inequality, one can obtain
Second, applying A1/2 to formula (29) and using estimates (11), (12), and (14) and the triangle inequality, we get
Now, we will prove estimates (25). Using formula (19), estimates (11), (12), (26), and (27), and the triangle inequality, we obtain
Note that the stability estimates obtained previously permit us to get the convergence estimate of difference scheme (2) under the smoothness property of solution (1). Actually, under the condition u(t) ∈ C([0,1], H), we can obtain the third order of accuracy for the error of difference scheme (2). Since , this condition is satisfied under the given data φ ∈ D(A3), ψ ∈ D(A5/2), , and f(0) ∈ D(A3).
Theorem 5. Let τ and h be sufficiently small numbers. Then, the solution of difference scheme (40) satisfies the following stability estimates:
The proof of Theorem 5 is based on the proof of abstract Theorem 4 and the symmetry property of operator defined by (38).
Acknowledgments
The authors would like to thank Professor Pavel E. Sobolevskii and reviewers for their helpful comments.