- Research
- Open access
- Published:
The optimal control problem with necessity condition for a viscous shallow water equation
Boundary Value Problems volume 2018, Article number: 71 (2018)
Abstract
The optimal control problem for a shallow water equation with a viscous term is analyzed. The existence of optimal control to the control problem is investigated. The necessity condition of optimal control is derived by using the first order Gâteaux derivative of cost functional and adjoint equation. The local uniqueness of the optimal control is established by means of the second order Gâteaux derivative of cost functional. The novelty of this paper is that the necessity condition and local uniqueness of optimal control to the problem are obtained with viscous coefficient \(\varepsilon>0\).
1 Introduction
This paper is concerned with the optimal control problem for a shallow water equation with a viscous term,
where k is a constant, \(m, a, b \in\mathbb {R}\), \(\Omega=[0,1]\subset \mathbb {R}\), \((t,x)\in\mathbb {R}^{+}\times\Omega\), \(\varepsilon (u_{xx}-u_{xxxx})\) is the viscous term and \(\varepsilon>0\) is the viscous coefficient.
We give a brief overview of a variety of related work in the literature. Constantin [1] derived the shallow water equation
where \(u(t,x)\) is the fluid velocity at time t in x direction and k is a constant related to the critical shallow water wave speed. They established the local well-posedness for the Cauchy problem of Eq. (1.2) and wave breaking phenomena of solutions. Lai [2] investigated the local well-posedness for the Cauchy problem of Eq. (1.2) in the Sobolev space \(H^{s}(\mathbb {R})\ (s > \frac{3}{2})\).
Taking \(\varepsilon=0, m=a+b\) in Eq. (1.1) yields a generalized shallow water equation. Lai [3] obtained the global existence of strong solutions and blow-up criterion of solutions to the Cauchy problem. For the case \(b=1\) in (1.1), Holm [4] not only studied the effects of balance parameter a and kernel function of solitary wave structures but also investigated their interactions analytically with \(\varepsilon =0\) and numerically with small viscosity \(\varepsilon\neq0\). Zhang [5] studied the optimal control problem for the generalized shallow water equation with a viscous term, which includes the viscous Camassa–Holm equation and viscous Degasperis–Procesi equation as special case. The optimal control and existence of optimal solution to the control problem are presented. Shen [6] investigated the optimal control problem for the θ-equation. The necessity optimal condition of optimal control to the control problem in fixed final horizon case is obtained by using functional analytical approach. In particular, taking \(\varepsilon=0, m=3, a=2, b=1\) in (1.1), we obtain the classical Camassa–Holm equation, which models the propagation of shallow water waves. For the methods to establish local well-posedness for the Cauchy problem of Camassa–Holm equation and global existence of solutions, one may refer to [7–9] and the references therein. Tian [10] studied the optimal control problem for a generalized viscous Camassa–Holm equation. They established the existence and uniqueness of local weak solutions by using the Galerkin method. The optimal control and existence of optimal solution were obtained. Shen [11–13] studied the optimal control problem for a generalized viscous shallow water equation. Zong [14] investigated the boundary stabilization for the viscous Camassa–Holm equation and nonviscous Camassa–Holm equation. The nonlinear boundary control laws and global asymptotical stabilization for the control problem are analyzed. If we take \(\varepsilon=0, m=4, a=3, b=1\) in (1.1), we obtain the classical Degasperis–Procesi equation. The local well-posedness for the Cauchy problem of the Degasperis–Procesi equation and blow-up mechanism of solutions were studied in [15, 16]. Tian [17] investigated the optimal control problem for a viscous Degasperis–Procesi equation by using the Galerkin method and optimal control theory of distributed parameter system.
However, the nonlinear partial differential equations created to model physical processes play an important role in almost all branches of mathematics. One may see more details in [18]. The well-posedness for the Cauchy problems and properties of solutions to the equations have been studied extensively. For example, Goubet and Hamraoui [19] investigated both numerically and theoretically the influence of a defect on the blow-up of radial solutions to the cubic nonlinear Schrodinger equation in two dimension. On the other hand, many researchers use the techniques in [20] to the study of the optimal control problems for fluids models [21–30]. The optimal control problems for the Dullin–Gottwald–Holm equation were studied in [31–33], which is similar in structure to the Camassa–Holm equation and the Degasperis–Procesi equation. Hwang [33] obtained the necessity optimal condition of optimal control to the control problem. The local uniqueness of optimal control was established by using the second order Gâteaux differentiability of cost functional. Zhao and Liu [22] investigated the existence of optimal control and optimal solution to the control problem for convective Cahn–Hilliard equation in three dimension. The first order necessity optimal condition of optimal control was presented. Leszczynski et al. [29] considered the optimal control problem for a general mathematical model of the drug treatment with a single agent. The sufficient condition for the strong local optimality of an extremal controlled trajectory was given. Papageorgiou et al. [30] presented the sensitivity analysis for the optimal control problems governed by nonlinear evolution inclusions. The non-emptiness of solution set and continuous selections of solution multifunction were investigated. In general, taking into account the viscous fluid is meaningful in physics. Castro [34] showed that the optimal control to the optimal control problem for the viscous Burgers equation converges to the nonviscous version as the viscosity coefficient tends to zero.
Motivated by the work in [6, 20, 29, 30, 32, 33], we studied the optimal control problem for the shallow water equation with a viscous term
where the control v and state \(u(v)\) satisfy the distributed control system
where \(y_{0}(x)\in L^{2}(\Omega)\), \(y(v)=u(v)-u_{xx}(v)\). \(f(t,x) \in L^{2}([0,T];H^{-1}(\Omega))\) is the force, \(v\in U_{\mathrm{ad}}\subset U\) is the control. The solution \(u(v)\) denotes the state of the control problem (1.4). \(B\in\mathcal{L} (U, L^{2}([0,T];H^{-1}(\Omega)))\) is a controller. The observation is \(z(v)=Cu(v)\), where \(C\in\mathcal {L}(S( 0,T ),M)\) is an observation operator and M is a Hilbert space of observation variables. The target \(z_{d}\in M\) is a desired value of \(u(v)\). \(N\in\mathcal {L} (U,U)\) is a self-adjoint, symmetric and positive operator, which satisfies
Let \(U_{\mathrm{ad}}\) be an admissible control set, which is a closed convex subset of U. The first term in the cost functional \(J(v)\) in (1.3) measures physical objective and the second term is size of control. The control object is to match the desired target \(z_{d}\) by adjusting control v in control volume \([0,T]\times\Omega\). An element \(v_{0}\in U\) which attains the minimum of cost functional \(J(v)\) over \(U_{\mathrm{ad}}\) is called an optimal control to the optimal control problem (1.3).
Firstly, we consider the local well-posedness for the problem
in the space \(S(0,T)\), where \(y=u-u_{xx}\) and \(f(t,x)\) is the force function. Secondly, we consider the optimal control problem (1.3).
Notation. Let \(V=H_{0}^{1}(\Omega), H=L^{2}(\Omega), H^{\ast}=L^{2}(\Omega), V^{*}=H^{-1}(\Omega)\). We have the embedding properties \(V\hookrightarrow H=H^{*}\hookrightarrow V^{*}\) in which each embedding is dense. The inner product in V is \((\phi,\varphi)_{V}=(\phi_{x},\varphi _{x})_{H}\), for all \(\phi, \varphi\in V\). For \(a\lesssim b\), we mean that there exists a uniform constant C, which may be different on different lines such that \(a\leq C b\). The spaces \(W([0,T];V)=\{f| f\in L^{2}([0,T];V),f_{t}\in L^{2}([0,T];V^{*})\}\), \(S(0,T)=\{f | f \in L^{2}([0,T];H_{0}^{3}(\Omega)),f_{t} \in L^{2}([0,T];H_{0}^{1}(\Omega))\}\) and \(W(H_{0}^{2},L^{2})=\{f|f\in L^{2}([0,T];H_{0}^{2}(\Omega)),f_{t}\in L^{2}([0,T];L^{2}(\Omega))\}\) are Hilbert spaces endowed with common inner product. Since the functions in all spaces are over Ω, we drop Ω if there is no ambiguity. As in the convergence case, the symbol ⇀ denotes the weak convergence.
2 Main results
The precise statements of the main results in this paper are listed.
Theorem 2.1
Assume \(f\in L^{2}([0,T];H^{-1}(\Omega)), u_{0}\in H^{2}_{0}(\Omega)\). Then problem (1.5) admits a unique local solution \(u\in S(0,T)\). The solution mapping \(p=(u_{0},f)\rightarrow u(p)\) from \(P_{0}=H^{2}_{0}(\Omega)\times L^{2}([0,T];H^{-1}(\Omega))\) into \(S(0,T)\) is local Lipschitz continuous. For each \(p_{1}=(u_{10},f_{1}), p_{2}=(u_{20},f_{2})\in P_{0}\),
In addition, if \(Bw\in L^{2}([0,T];H^{-1}(\Omega))\), there exists an optimal control \(v_{0}\) to the optimal control problem (1.3).
Theorem 2.2
Assume \(Bw,f\in L^{2}([0,T];H^{-1}(\Omega)), u_{0}\in H^{2}_{0}(\Omega)\). For the control problem (1.4), the solution mapping \(v\rightarrow u(v)\) from U into \(S(0,T)\) is Gâteaux differentiable at \(v=v_{0}\). Let \(z=Du(v_{0})w \) be the Gâteaux direction derivative of \(u(v)\) at \(v=v_{0}\) in direction w, where \(w=v-v_{0}\). Thus \(z=Du(v_{0})w\) is the unique solution to the problem
where .
Theorem 2.3
Assume \(Bw,f\in L^{2}([0,T];H^{-1}(\Omega)), u_{0}\in H^{2}_{0}(\Omega)\). We have:
-
(i)
the necessity condition of optimal control v to the optimal control problem (5.7) is characterized by (3.17), (5.9) and (5.12);
-
(ii)
the necessity condition of optimal control v to the optimal control problem (5.13) is characterized by (3.17), (5.15) and (5.17).
Theorem 2.4
Assume \(Bw,f\in L^{2}([0,T];H^{-1}(\Omega)), u_{0}\in H^{2}_{0}(\Omega)\). If \(T=T(\nu)\) is small, there exists a unique optimal control v to the optimal control problem (5.13).
The remainder of this paper is organized as follows. The proofs of Theorems 2.1, 2.2, 2.3 and 2.4 are presented in Sects. 3, 4, 5 and 6, respectively. The conclusions in this paper are presented in Sect. 7.
3 Existence and uniqueness of weak solutions
We recall the definition of weak solutions and a related lemma.
Definition 3.1
Let \(y_{0}(x)\in H \). The function \(u(t,x)\in S(0,T)\) is a weak solution to problem (1.5) if \(y(t,x)\in W([0,T];V)\) and \(y(t,x)\) satisfies
Lemma 3.1
([33])
Let u satisfy the boundary conditions in (1.5) and assume \(u-u_{xx}\in W([0,T];V)\). Then we have \(\Vert u \Vert _{S(0,T)}\lesssim \Vert u-u_{xx} \Vert _{W([0,T];V)} \).
Proof of Theorem 2.1
Using condition \(p=(u_{0},f)\in P_{0}\) and the Galerkin method as in [5, 13, 32] with suitable modifications, we deduce that problem (1.5) possesses a unique local solution \(u\in S(0,T)\).
We are ready to present the detailed derivation for (2.1). Let \(\phi=u_{1}-u_{2}=u(p_{1})-u(p_{2})\) and \(\Phi=\phi-\phi_{ xx}\). Then we have
Multiplying (3.2) by Φ and integrating with respect to x and t on \([0,T]\times\Omega\) yield
Using the fact \(y_{1}, y_{2}\in W([0,T];V) \) yields
Applying the Gronwall inequality, we obtain
Using the first equation in (3.2) gives rise to
Taking into account (3.5) and (3.6), we have
It follows that
Applying Lemma 3.1 yields
We prove the existence of optimal control \(v_{0}\) to the optimal control problem (1.3).
Let \(J=\inf_{v\in U_{\mathrm{ad}}} J(v)\). We bear in mind that \(U_{\mathrm{ad}}\) is not empty. Then there exists a sequence \(\{v_{n}\}\subset U\) such that
Hence \(\{J(v_{n})\}\) is bounded. We deduce that there exists a constant \(K_{0}>0\) such that
which derives that \(\{v_{n}\}\) is bounded in U. Applying the property that \(U_{\mathrm{ad}}\) is closed and convex, we choose a subsequence of \(\{v_{n}\} \), still denoted by \(\{v_{n}\}\), such that \(v_{n}\rightharpoonup v_{0}\) in U as \(n\rightarrow\infty\).
Let the state \(u_{n}=u(v_{n})\in S(0,T)\) corresponding to control \(v_{n}\) be solution to problem
where \(y_{n}=u_{n}-u_{n,xx}\). Using (3.12), we obtain
Bearing in mind (3.8) gives rise to the inequality
Applying Lemma 3.1 yields
There exists a subsequence of \(\{y_{n}\}\), denoted by \(\{y_{n_{k}}\}\), and a function \(y=u-u_{xx}\in W([0,T];V)\) such that \(y_{n_{k}}\rightharpoonup y\) in \(W([0,T];V)\). Using the fact that \(H^{1}_{0}\hookrightarrow L^{2}\) is compact, we deduce that there exists a subsequence of \(\{y_{n}\}\), denoted by \(\{y_{n_{k}}\}\), such that \(y_{n_{k}}\rightarrow y\) in \(L^{2}([0,T];L^{2})\). Since the embedding \(W([0,T];V)\hookrightarrow C([0,T];L^{2})\) is compact, we deduce \(u_{n}\in C([0,T];H_{0}^{2})\). Then there exists a subsequence of \(\{u_{n}\}\), denoted by \(\{u_{n_{k}}\}\), such that \(u_{n_{k}}\rightarrow u\) in \(H_{0}^{2}\), for a.e. \(t\in[0,T]\). Hence
as \(k\rightarrow\infty\). We replace \(u_{n}, y_{n}\) by \(u_{n_{k}}, y_{n_{k}}\) in (3.12), respectively. Taking \(k\rightarrow\infty\) shows that the limit function y satisfies
in the weak solution sense.
From Theorem 2.1, we obtain the uniqueness of weak solutions to problem (3.17). Then we deduce that \(u=u(v_{0})\in S(0,T)\) and \(u(v_{n})\rightharpoonup u(v_{0})\) in \(S(0,T)\). The operator C is continuous on \(S(0,T)\) and \(\Vert \cdot \Vert _{M}\) is lower semicontinuous. Hence
It deduces from \(\lim\inf_{n\rightarrow\infty} \Vert N^{\frac {1}{2}}v_{n} \Vert _{U}\geq \Vert N^{\frac{1}{2}}v_{0} \Vert _{U}\) that \(\lim\inf_{n\rightarrow\infty} (Nv_{n},v_{n}) _{U}\geq (Nv_{0},v_{0}) _{U}\). Then \(J=\lim\inf_{n\rightarrow\infty}J(v_{n})\geq J(v_{0})\). Meanwhile, from (3.10), we derive \(J(v_{0})\geq J\). Hence \(J(v_{0})=\inf_{v\in U_{\mathrm{ad}}}J(v)\). This completes the proof of Theorem 2.1. □
4 The proof of Theorem 2.2
From Theorem 2.1, we define the unique solution map \(v\rightarrow u(v)\) from U into \(S(0,T)\). Let \(DJ(v_{0})\) be the Gâteaux derivative of \(J(v)\) defined in (1.3) at \(v=v_{0}\). We intend to investigate the necessity optimal condition of optimal control
We use the adjoint equation (5.2) of (1.4) to give detail expression for (4.1).
The definition of the Gâteaux differentiability of solution mapping is presented.
Definition 4.1
([33])
For the control problem (1.4), the solution map \(v\rightarrow u(v)\) from U into \(S(0,T)\) is Gâteaux differentiable at \(v=v_{0}\), if for all \(w\in U\), there exists \(Du(v_{0})\in\mathcal {L}(U,S(0,T))\) such that
The operator \(Du(v_{0})\) is the Gâteaux derivative of \(u(v)\) at \(v=v_{0}\) and the function \(Du(v_{0})w\in S(0,T)\) is the Gâteaux direction derivative of \(u(v)\) at \(v=v_{0}\) in direction \(w \in U\).
Proof of Theorem 2.2
Let \(\lambda\in(-1,0)\cup(0,1), w=v-v_{0}\) and \(z_{\lambda}=\frac{u(v_{0}+\lambda w)-u(v_{0})}{\lambda}\). Using (1.4) and (3.17), we deduce that \(z_{\lambda}\) satisfies
where \(u_{\lambda}=u(v_{0}+\lambda w)\), \(y_{\lambda}=u_{\lambda }-u_{\lambda,xx} \) and .
From Theorem 2.1, we have
Hence
We deduce that there exist \(z\in S(0,T)\) and a sequence \(\{\lambda_{k}\} \subset(-1,1)\rightarrow0\) such that \(z_{\lambda_{k}}\rightharpoonup z\) in \(S(0,T)\) as \(k\rightarrow\infty\). Using the Aubin compact lemma gives rise to \(z_{\lambda_{k}}\rightarrow z\) in \(H_{0}^{2}\), for a.e. \(t\in[0,T]\). From the Lebesgue dominated convergence theorem, we obtain
as \(k\rightarrow\infty\), where \(y=u(v_{0})-u_{xx}(v_{0})\), .
Therefore in \(L^{2}([0,T];H ^{-1})\). Then \(z_{\lambda}\rightharpoonup z=Du(v_{0})w\) in \(S(0,T)\) as \(\lambda \rightarrow0\), where z is the solution to problem (2.2).
In what follows we present the derivation that \(z_{\lambda}\rightarrow z=Du(v_{0})w\) in \(S(0,T)\) as \(\lambda\rightarrow0\).
Let \(\phi_{\lambda}=z_{\lambda}-z\) and \(\Phi_{\lambda}=\phi_{\lambda }-\phi_{\lambda,xx}\). From (2.2) and (4.3), we derive
where \(\theta(\lambda)=-[(m-a-b)(z_{\lambda}u_{\lambda,x}-zu_{x} )+a(z_{\lambda,x} y_{\lambda}-z_{x}y)+b(z_{\lambda}y_{\lambda,x}-zy_{x})]\).
Bearing in mind (4.6) shows that \(\theta(\lambda)\rightarrow0\) in \(L^{2}([0,T];L^{2})\) as \(\lambda\rightarrow0\).
We need to establish the estimates for \(\phi_{\lambda}\). Multiplying (4.7) by \(\Phi_{\lambda}\) and using integration by parts, we obtain
Then we have
Using (4.7) and (4.9) gives rise to
Thus we obtain \(\Phi_{\lambda} \rightarrow0\) in \(W([0,T];V)\). Applying Lemma 3.1 yields \(z_{\lambda} \rightarrow z\) in \(S(0,T)\). We complete the proof of Theorem 2.2. □
5 Necessity optimal condition of optimal control
We are in the position to present the necessity optimal condition of optimal control to the optimal control problem (1.3).
Theorem 2.2 implies that the cost functional \(J(v)\) is Gâteaux differentiable at \(v=v_{0} \) in the direction \(v-v_{0}\). Using
and \(J(v_{0})=(Cu(v_{0})-z_{d},Cu(v_{0})-z_{d})_{M}+(Nv_{0},v_{0})_{U}, w=v-v_{0}\), we have
Let Λ be the isomorphism mapping from M onto \(M^{\ast}\). Applying (4.1), we rewrite the necessity optimal condition of the optimal control as
for all \(v\in U_{\mathrm{ad}}\).
Similar to the methods in [20], we derive the necessity optimal condition via the adjoint equation,
where \(P=p(v_{0};t,x)-p_{xx}(v_{0};t,x)\), \(f_{3}=C^{*}\Lambda(Cu(v_{0})-z_{d})\).
The local well-posedness for problem (5.2) is given by the following lemma.
Lemma 5.1
Assume \(C^{*}\Lambda(Cu(v_{0})-z_{d})\in L^{2}([0,T];H^{-2}(\Omega))\) and reverse the direction of time \(t\rightarrow T-t\) in (5.2). Problem (5.2) admits a unique solution \(p(v_{0})\) satisfying
where \(P=p(v_{0})-p_{xx}(v_{0})\).
Proof of Lemma 5.1
Let \(p(v_{0})=p\). By reversing the time \(t\rightarrow T-t\), we change problem (5.2) into
We use the Galerkin method as in [13, 32] to establish the local well-posedness for problem (5.3). We present the main derivations.
Multiplying (5.3) by p and integrating by parts yield
Hence, the approximate solution sequence \(\{p_{n}\}\) is uniformly bounded in \(L^{2}([0,T];H_{0}^{2})\). Using the property of operator \((1-\partial _{x}^{2})^{-1}\), (5.3) and (5.4), we deduce that \(\{p_{n,t}\}\) is bounded in \(L^{2}([0,T];L^{2})\). Thus \(\{ p_{n}\}\) is bounded in \(W(H_{0}^{2};L^{2})\). Applying the Aubin compact lemma, we deduce that there exists a limit function \(p\in W(H_{0}^{2};L^{2})\), which is the unique solution to problem (5.3). This completes the proof of Lemma 5.1. □
For simplicity, we consider the observations in the following two cases.
(1) Let \(M=L^{2}([0,T]\times\Omega), C_{3}\in\mathcal{L}(S(0,T),M)\) and observation
(2) Assume \(M=L^{2}([0,T]\times\Omega), C_{4}\in\mathcal{L}(S(0,T),M)\) and observation
Proof of Theorem 2.3
For the case of observation in (5.5), we consider the optimal control problem
where \(u(v)\) is the state in (1.4).
Let \(v_{0}\) be the optimal control to the optimal control problem (5.7). Then the necessity optimal condition (5.1) is rewritten into the form
We consider the adjoint system
where \(P=p(v_{0} )-p_{xx}(v_{0} ), y(v_{0})=u(v_{0} )-u_{xx}(v_{0} )\).
Note that the observation \(u(v_{0})-z_{d}\in L^{2}([0,T]\times\Omega)\subset L^{2}([0,T];H^{-2})\). Using Lemma 5.1 shows that problem (5.9) admits a unique solution \(p(v_{0})\in W(H_{0}^{2},L^{2})\).
Multiplying (5.9) by \(z(t,x)\) and integrating over \([0,T]\times\Omega\), we have
Applying (2.2) and (5.10) yields
From (5.10) and (5.11), we see that (5.8) is equivalent to
We complete the proof of case (i) in Theorem 2.3.
For the observation in (5.6), we consider the optimal control problem
where \(y(v)=u(v)-u_{xx}(v)\), \(u(v)\) is the state in (1.4).
Similar to (5.8), the necessity optimal condition (5.1) is rewritten as
We consider the adjoint system
where \(P=p(v_{0} )-p_{xx}(v_{0} ), y(v_{0})=u(v_{0} )-u_{xx}(v_{0} )\).
Bearing in mind \((1-\partial_{x}^{2})( y(v_{0})-z_{d} )\in L^{2}([0,T];H^{-2})\), we deduce from Lemma 5.1 that problem (5.15) admits a unique solution \(p(v_{0})\in W(H_{0}^{2},L^{2})\).
Multiplying (5.15) by \(z(t,x)\) and integrating by parts, we obtain
Thus, the necessity optimal condition (5.14) is equivalent to
We complete the proof of case (ii) in Theorem 2.3. □
6 Local uniqueness of optimal control
Firstly, we give a lemma on the local uniqueness of optimal control to the optimal control problem (5.13).
Lemma 6.1
For the control problem (1.4), the mapping \(v\rightarrow u(v)\) from U into \(S(0,T)\) is the second order Gâteaux differentiable at \(v=v_{0}\). The second order Gâteaux direction derivative of \(u(v)\) at \(v=v_{0}\) in the direction \(v-v_{0}\in U\), say \(g=D^{2}u(v_{0})( v-v_{0},v-v_{0})\) is the unique solution to the problem
where \(G(t,x)=g-g_{xx}\). And g satisfies the estimates
Proof of Lemma 6.1
The proof of that g is the unique solution to problem (6.1) is similar to the proof of Theorem 2.2. We omit the detail derivation. Using the fact that z is the solution to problem (2.2) gives rise to
Hence
From (6.3) and (6.4), we obtain (6.2). □
Proof of Theorem 2.4
We only present the proof for the case of observation in (5.6). The similar result holds for (5.5). We establish the local uniqueness of optimal control by proving the strict convexity of map \(v\in U_{\mathrm{ad}}\rightarrow J(v)\). Namely, for all \(v_{1}, v_{2}\in U_{\mathrm{ad}}\), let \(w=v_{2}-v_{1}\), then
Let us denote \(u(v_{1}+\theta(v_{2}-v_{1})), z(v_{1}+\theta (v_{2}-v_{1})),g(v_{1}+\theta(v_{2}-v_{1}))\) by \(u(\theta),z(\theta), g(\theta )\), respectively. It follows
where .
Using (6.6), we obtain
Applying Lemma 6.1, we have
If \(T=T(\nu)\) is small, using (6.7) gives rise to (6.5). Hence, we obtain the strict convexity of cost functional \(J(v)\), where \(v\in U_{\mathrm{ad}}\). This completes the proof of Theorem 2.4. □
7 Conclusions
In this work, we studied the optimal control problem for a shallow water equation with a viscous term and viscous coefficient \(\varepsilon >0\). The existence of optimal control to the control problem is investigated. The necessity condition of optimal control is derived by using the first order Gâteaux derivative of the cost functional and the adjoint equation. The local uniqueness of optimal control is established by means of the second order Gâteaux derivative of the cost functional. Due to the independence of coefficients m, a and b in (1.4), the nonlinear term \(uu_{x}\) does not disappear after using the transformation \(y=u-u_{xx}\), which leads to the difficulty of establishing the estimates for term \(uu_{x}\). This is the major improvement in comparison with the results in the literature [5, 10, 17, 32], where the problems studied are special cases of the optimal control problem (1.3) in this paper. Moreover, we obtain the necessity condition and local uniqueness of optimal control to the optimal control problem (1.3) by using the Gâteaux derivative of cost functional. This is another novelty of our paper.
References
Constantin, A., Lannes, D.: The hydrodynamical relevance of the Camassa–Holm and Degasperis–Procesi equations. Arch. Ration. Mech. Anal. 192, 165–186 (2009)
Lai, S.Y., Wu, Y.H.: A model containing both the Camassa–Holm and Degasperis–Procesi equations. J. Math. Anal. Appl. 374, 458–469 (2011)
Lai, S.Y., Wu, Y.H.: Global solutions and blow-up phenomena to the shallow water equation. J. Differ. Equ. 249, 693–706 (2010)
Holm, D.D., Staley, M.F.: Wave structures and nonlinear balances in a family of \(1+1\) evolutionary PDEs. SIAM J. Appl. Dyn. Syst. 2, 323–380 (2003)
Zhang, W.B., Zhou, J.B.: Optimal control of a viscous shallow water equation. Adv. Math. Phys. 2013, 715959 (2013)
Shen, C.Y.: Optimal control of a class of nonlocal dispersive equations. Nonlinear Anal. 108, 99–113 (2014)
Li, Y., Olver, P.: Well-posedness and blow-up solutions for an integrable nonlinearly dispersive model wave equation. J. Differ. Equ. 162, 27–63 (2000)
Guan, C.X., Yin, Z.Y.: Global weak solutions for a 2-component Camassa–Holm shallow water system. J. Funct. Anal. 260, 1132–1154 (2011)
Gui, G.L., Liu, Y.: On the global existence and wave-breaking criteria for the 2-component Camassa–Holm system. J. Funct. Anal. 258, 4251–4278 (2010)
Tian, L.X., Shen, C.Y., Ding, D.P.: Optimal control of the viscous Camassa–Holm equation. Nonlinear Anal., Real World Appl. 10, 519–530 (2009)
Shen, C.Y., Gao, A.N.: Optimal solution for the viscous nonlinear dispersive wave equation. J. Math. Phys. 51, 053520 (2010)
Gao, A.N., Shen, C.Y.: Optimal solution for the viscous modified Camassa–Holm equation. J. Nonlinear Math. Phys. 17, 571–589 (2010)
Shen, C.Y., Gao, A.N., Tian, L.X.: Optimal control of the viscous generalized Camassa–Holm equation. Nonlinear Anal., Real World Appl. 11, 1835–1846 (2010)
Zong, X.J.: On the global boundary stabilization of the Camassa–Holm equation. Nonlinear Anal., Real World Appl. 15, 221–228 (2014)
Liu, Y., Yin, Z.Y.: Global existence and blow-up phenomena for the Degasperis–Procesi equation. Commun. Math. Phys. 267, 801–820 (2006)
Yin, Z.Y.: Global existence for a new periodic integrable equation. J. Math. Anal. Appl. 283, 129–139 (2003)
Tian, L.X., Shen, C.Y.: Optimal control of the viscous Degasperis–Procesi equation. J. Math. Phys. 48, 113513 (2007)
Ghergu, M., Radulescu, V.: Nonlinear PDEs, Mathematical Models in Biology, Chemistry and Population Genetics. Springer, Berlin (2012)
Goubet, O., Hamraoui, E.: Blow-up of solutions to cubic nonlinear Schrodinger equations with defect: the radial case. Adv. Nonlinear Anal. 6, 183–197 (2017)
Lions, J.L.: Optimal Control of Systems Governed by Partial Differential Equations. Springer, Berlin (1971)
Liu, C.C., Wang, Z.: Optimal control for a sixth order nonlinear parabolic equation. Math. Methods Appl. Sci. 38, 247–262 (2015)
Zhao, X.P., Liu, C.C.: Optimal control for convective Cahn–Hilliard equation in 2D case. Appl. Math. Optim. 70, 61–82 (2014)
Marburger, J., Pinnau, R.: Optimal control for Burgers equation using particle methods (2013). arXiv:1309.7619v1
Yong, J.M., Zheng, S.M.: Feedback stabilization and optimal control for the Cahn–Hilliard equation. Nonlinear Anal. 17, 431–444 (1991)
Shen, C.Y., Gao, A.N.: Optimal distributed control of the Fornberg–Whitham equation. Nonlinear Anal., Real World Appl. 21, 127–141 (2015)
Guerra, T., Tiago, J., Sequeira, A.: On the optimal control of a class of non-Newtonian fluids (2015). arXiv:1510.04077v1
Casas, E., Troltzsch, F.: Second order optimality conditions and their role in PDE control. Jahresber. Dtsch. Math.-Ver. 117, 3–44 (2015)
Zhang, L., Liu, B.: Optimal distributed controls of a class of nonlinear dispersive equations with cubic nonlinearity. Nonlinear Anal. 122, 23–42 (2015)
Leszczynski, M., Ratajczyk, E., Ledzewicz, U., Schattler, H.: Sufficient conditions for optimality for a mathematical model of drug treatment with pharmacodynamics. Opusc. Math. 37, 403–419 (2017)
Papageorgiou, N., Radulescu, V., Repovs, D.: Sensitivity analysis for optimal control problems governed by nonlinear evolution inclusions. Adv. Nonlinear Anal. 6, 199–235 (2017)
Sun, B.: Maximum principle for optimal distributed control of the viscous Dullin–Gottwald–Holm equation. Nonlinear Anal. 13, 325–332 (2012)
Shen, C.Y., Tian, L.X., Gao, A.N.: Optimal control of the viscous Dullin–Gottwalld–Holm equation. Nonlinear Anal., Real World Appl. 11, 480–491 (2010)
Hwang, J.: Optimal control problem with necessary optimality conditions for the viscous Dullin–Gottwald–Holm equation. Abstr. Appl. Anal. 2014, 623129 (2014)
Castro, C., Palacios, F., Zuazua, E.: Optimal control and vanishing viscosity for the Burgers equation. Int. Methods Sci. Eng. 2, 65–90 (2010)
Acknowledgements
We are grateful to the anonymous referees for a number of valuable comments and suggestions.
Availability of data and materials
Not applicable.
Funding
This paper is supported by National Natural Science Foundation of P.R. China (11471263) and Scientific Research Foundation of North University of China (2017030) and (13011920).
Author information
Authors and Affiliations
Contributions
Both authors contributed equally and significantly in writing this article. Both authors read and approved the final manuscript.
Corresponding author
Ethics declarations
Ethics approval and consent to participate
Both authors contributed to each part of this study equally and declare that they have no competing interests.
Competing interests
The authors declare that they have no competing interests.
Consent for publication
Both authors read and approved the final version of the manuscript.
Additional information
Abbreviations
Not applicable.
Publisher’s Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
About this article
Cite this article
Ming, S., Lai, S. & Su, Y. The optimal control problem with necessity condition for a viscous shallow water equation. Bound Value Probl 2018, 71 (2018). https://doi.org/10.1186/s13661-018-0989-8
Received:
Accepted:
Published:
DOI: https://doi.org/10.1186/s13661-018-0989-8