Loading [MathJax]/jax/element/mml/optable/BasicLatin.js
Research article Special Issues

The well-posedness for semilinear time fractional wave equations on RN


  • This paper is concerned with the semilinear time fractional wave equations on the whole Euclidean space, also known as the super-diffusive equations. Considering the initial data in the fractional Sobolev spaces, we prove the local/global well-posedness results of L2-solutions for linear and semilinear problems. The methods of this paper rely upon the relevant wave operators estimates, Sobolev embedding and fixed point arguments.

    Citation: Yong Zhou, Jia Wei He, Ahmed Alsaedi, Bashir Ahmad. The well-posedness for semilinear time fractional wave equations on RN[J]. Electronic Research Archive, 2022, 30(8): 2981-3003. doi: 10.3934/era.2022151

    Related Papers:

    [1] Yaning Li, Mengjun Wang . Well-posedness and blow-up results for a time-space fractional diffusion-wave equation. Electronic Research Archive, 2024, 32(5): 3522-3542. doi: 10.3934/era.2024162
    [2] Anh Tuan Nguyen, Chao Yang . On a time-space fractional diffusion equation with a semilinear source of exponential type. Electronic Research Archive, 2022, 30(4): 1354-1373. doi: 10.3934/era.2022071
    [3] Vo Van Au, Jagdev Singh, Anh Tuan Nguyen . Well-posedness results and blow-up for a semi-linear time fractional diffusion equation with variable coefficients. Electronic Research Archive, 2021, 29(6): 3581-3607. doi: 10.3934/era.2021052
    [4] Mingfa Fei, Wenhao Li, Yulian Yi . Numerical analysis of a fourth-order linearized difference method for nonlinear time-space fractional Ginzburg-Landau equation. Electronic Research Archive, 2022, 30(10): 3635-3659. doi: 10.3934/era.2022186
    [5] Lin Shen, Shu Wang, Yongxin Wang . The well-posedness and regularity of a rotating blades equation. Electronic Research Archive, 2020, 28(2): 691-719. doi: 10.3934/era.2020036
    [6] Dan-Andrei Geba . Unconditional well-posedness for the periodic Boussinesq and Kawahara equations. Electronic Research Archive, 2024, 32(2): 1067-1081. doi: 10.3934/era.2024052
    [7] Lingrui Zhang, Xue-zhi Li, Keqin Su . Dynamical behavior of Benjamin-Bona-Mahony system with finite distributed delay in 3D. Electronic Research Archive, 2023, 31(11): 6881-6897. doi: 10.3934/era.2023348
    [8] Yitian Wang, Xiaoping Liu, Yuxuan Chen . Semilinear pseudo-parabolic equations on manifolds with conical singularities. Electronic Research Archive, 2021, 29(6): 3687-3720. doi: 10.3934/era.2021057
    [9] Yang Liu, Wenke Li . A family of potential wells for a wave equation. Electronic Research Archive, 2020, 28(2): 807-820. doi: 10.3934/era.2020041
    [10] Hyungyeong Jung, Sunghwan Moon . Reconstruction of the initial function from the solution of the fractional wave equation measured in two geometric settings. Electronic Research Archive, 2022, 30(12): 4436-4446. doi: 10.3934/era.2022225
  • This paper is concerned with the semilinear time fractional wave equations on the whole Euclidean space, also known as the super-diffusive equations. Considering the initial data in the fractional Sobolev spaces, we prove the local/global well-posedness results of L2-solutions for linear and semilinear problems. The methods of this paper rely upon the relevant wave operators estimates, Sobolev embedding and fixed point arguments.



    In this paper, we focus on the following time fractional wave equation

    βtuΔu=f(u),t>0, (1.1)

    supplemented with the initial conditions

    u(0,x)=ϕ(x), tu(0,x)=ψ(x),xRN, (1.2)

    where βt stands for the Caputo fractional derivative operator of order β(1,2), Δ is the Laplacian operator, and f is the semilinear data to be specified later, initial data ϕ, ψ are given in certain fractional Sobolev spaces, likely (ϕ,ψ)Hs(RN)×Hs1(RN) for sR.

    From the point of view of physics, it's often better for fractional derivatives to fit practical problems than the integer order setting counterpart in many cases, for example, Hamiltonian chaos [1], biophysics [2,3], control engineering [4,5], viscoelasticity [6,7], anomalous diffusion [8,9,10,11], switched systems [12], and other problems [13,14,15]. In particular, the study of the Eq (1.1) has always been an important topic in the mathematical physics as it represents anomalous diffusion phenomena. The time fractional partial differential equation βtu=Δu of order β(0,1) models anomalous diffusion phenomena ensuring the behavior of a subdiffusion process driven by a fractional Brownian motion [16]. The case of order β(1,2) will govern intermediate processes between diffusion and wave propagation, for example, see [7], and it also ensures the behavior of superdiffusion process, for instance, see [17]. While the cases β1+ and β2 respectively correspond to standard diffusion equation (heat equation) and ballistic diffusion (wave equation). Besides, in anomalous diffusion equations of order β(0,1) or β(1,2), the mean squared displacement of a diffusive particle behavior likes x2(t)tβ, in contrast to normal diffusion behavior (Brownian motion) x2(t)t.

    There are many recent interesting works about time fractional wave equations. One of the most favorable reasons is that the integral kernel in fractional time derivative represents memory of a long-time tail of the power order. The investigation of existence and uniqueness of solutions for a low regularity initial data is a matter of interest in the mathematical analysis. For instance, Kian and Yamamoto [18] investigated a weak solution for semilinear case of (1.1) in bounded domain Ω for dimension n=2,3. By using the technique of eigenvalue expansion together with the properties of Mittag-Leffler functions, they established the existence and uniqueness results, which the solution shall lie in Lp(0,T;Lq(Ω))C([0,T];H2r(Ω)) for r=min(11/β,γ) with some 1p,q,0<γ<1. Following this technique, Alvarez et al. [19] considered the well-posedness for an abstract Cauchy problem in a Hilbert space, where the solutions will lie in Lrq(0,T;L2r(X)) associated with initial data (ϕ,ψ)D(Aγ)×L2(X), D(Aγ) are the fractional power spaces with spectrum form of A (nonnegative self-adjoint operator) for some β(1,2), γ=1/β, X is a (relatively) compact metric space and q(1/(β1),], r>1. Moreover, Otarola and Salgado [20] studied the time and space regularities of weak solutions for the space-time fractional wave equations, Zhou and He [21] discussed a well-posedness and time regularity of mild solutions for time fractional damped wave equations, etc. For more details, we refer to see the papers [22,23,24,25,26].

    However, few results discuss the unbounded domain case, likely the whole Euclidean space RN. This is due the difficulty to establish the relevant estimates on solution operators, also the method of eigenvalue expansion is not appropriate to such problem. As we know, Alemida and Precioso [27] investigated the global existence with large initial data in the framework of Besov-Morrey spaces, Alemida and Viana [28] studied existence, stability, self-similarity and symmetries of solutions with initial data in Sobolev-Morrey space. Zhang and Li [29] studied the local existence on C([0,T],Lq(RN)) for βN(p1)/2<q for a special semilinear function f|u|p, also the critical exponents of the global existence and blow-up solutions are determined when ψ0 and ψ0. Djida et al. [30] worked on a well-posedness result for semilinear space-time fractional wave equations, by adopting the method of Laplace-Fourier transforms, the properties of Mittag-Leffler functions and Fox H-functions.

    Our goal in this work is to establish the well-posedness results for time fractional wave equations with initial conditions in certain function spaces. More precisely, we consider linear and semilinear problems on RN, and present a general assumption in semilinear function and a special case λ|u|αu to deal with the current problem. In addition, this paper is devoted to studying the well-posedness of mild solutions to the current problems. In order to obtain the solution operators for time fractional wave equation and their properties, we shall establish some useful estimates which depend on that of wave operators. We remark that our proofs and results are completely different from the previous mentioned works. We will concern about the local/global well-posedness of solutions. Let us now enlist the main results presented in this paper:

    Ⅰ. The solution operators of Eq (1.1). Let ϖ=(Δ)1/2, we know that the wave operators can be given by cos(ϖt) and ϖ1sin(ϖt). Concerned with the principle of subordination, two inherent relationships between probability density function and wave operators are presented. More precisely, we get

    Cσ(t)=0Mσ(θ)cos(ϖtσθ)dθ,Sσ(t)=σtσ10θMσ(θ)ϖ1sin(ϖtσθ)dθ.

    To the best of our knowledge, these forms of solution operators are completely different from the existing literatures, relying upon the estimates of wave operators, some useful estimates of solution operators can be derived, which provide very helpful tools for the proofs. Observe that, the probability density function builds a bridge between integer wave equations and the fractional ones.

    Ⅱ. The well-posedness results on RN. We first establish some estimates on several spaces for the linear problem with initial data (ϕ,ψ)Hs(RN)×Hs1(RN), and then an existence of L2-solution is established on a space of continuous functions. Next, under the case that the semilinear function f:L2(RN)Lr(RN)Lr(RN), and satisfies

    f(u)f(v)Lr(RN)Cα(R)(uαLr(RN)+vαLr(RN))uvLr(RN),

    where constants r and α satisfy some restriction requirements, the local well-posedness results of mild solutions are established in the framework of Lγ(Lγ) spaces, here γ and γ are the conjugate indices. By concerning with a special semilinear data fλ|u|αu, we show that the local well-posedness on Besov space Bsr,2(RN). Furthermore, when ψ0, we also show the global existence to the Cauchy problem (1.1)–(1.2).

    The rest of this paper is divided into three sections. In Section 2, some basic notations and useful preliminaries are introduced. In Section 3, for the linear problem, we derive the solution operators and establish their some properties. In addition, two existence of L2-solutions are given. In Section 4, we prove some local/global well-posedness results on Lebesgue and Besov spaces for the semilinear problems.

    In this section, some notations and preliminaries related to our work will be introduced.

    Denote by Lq(RN) (q1) the Lebesgue space of q-integrable functions with the norm Lq(RN). Let S(RN) be the Schwartz space and let S(RN) denote its topological dual, for any vS(RN), F represents the Fourier transform

    ˆv(ξ)=F(v)(ξ)=(2π)N/2RNeixξv(x)dx,

    with its inverse

    ˇv(x)=F1(v)(x)=(2π)N/2RNeixξv(x)dx.

    Define the Sobolev space by

    Hs,q(RN)={uS(RN): F1[(1+|ξ|2)s2F(u)]Lq(RN)},

    equipped with the norm

    uHs,q(RN):=F1[(1+|ξ|2)s2F(u)]Lq(RN),

    for sR, 1q. We also use the Besov space Bsp,q:=Bsp,q(RN) and homogeneous Besov space ˙Bsp,q:=˙Bsp,q(RN), for sR, 1p,q. For the definitions and properties of Besov spaces, we refer to see [31,32]. In particular, it yields H0,p(RN)=Lp(RN) and Hs(RN)=Hs,2(RN)=Bs2,2(RN) for p1 and sR. Throughout this paper, we denote the notation ab that stands for aCb, with a positive generic constant C that does not depend on a,b, the notations , stand for ab=max{a,b} and ab=min{a,b}, respectively. Let p and p be the conjugate indices such that 1/p+1/p=1.

    Let T>0 (or T=+) and let X be a usual Banach space. For any uL1(0,T;X) and vL1(0,T;X), denote the convolution by

    (uv)(t)=t0u(ts)v(s)ds,t0,

    and for β0 let the weak singular kernel gβ() be defined by

    gβ(t)=tβ1/Γ(β),t>0,

    where Γ() is the usual gamma function. We denote g0(t)=δ(t), the Dirac measure is concentrated at the origin. Next, let us recall the concepts of fractional calculus and Mittag-Leffler functions. The Riemann-Liouville fractional integral of order β0 for a function vL1(0,T;X) is defined as

    Jβtv(t)=1Γ(β)t0(ts)β1v(s)ds=(gβv)(t), t>0.

    Definition 2.1. Let β(1,2). Consider a function vL1(0,T;X) such that convolution g2βvW2,1(0,T;X). The representation

    βtv(t)=2tt(g2β[v(t)v(0)ttv(0)]),t>0,

    is called the Caputo fractional derivative of order β.

    An important special function for the fractional differential equations involving the Caputo fractional derivative is the Mittag-Leffler function, which is defined by

    Eν,μ(z)=k=0zkΓ(νk+μ),zC, ν>0, μR.

    Note that, if w(t):=Eν,1(atν), ν(0,2), aR, then one can check that w is the solution of the equation νtw(t)=aw(t).

    Let the probability density function Mυ() (also called Mainardi's Wright function) be defined by

    Mυ(z)=k=0(z)kk!Γ(1υ(k+1)),υ(0,1), zC.

    For θ>0, this probability density function has the properties

    Mυ(θ)0,0θδMυ(θ)dθ=Γ(1+δ)Γ(1+υδ),for 1<δ<. (2.1)

    Next, we see that the probability density function can be viewed as a bridge between the classical and fractional wave equations.

    Lemma 2.1. Let β(1,2) [21]. Then for zC, the following formulas expressing the Mittag-Leffler function in term of probability density function hold:

    Eβ,1(z2)=0Mβ/2(θ)cos(zθ)dθ,Eβ,β(z2)=β2z0θMβ/2(θ)sin(zθ)dθ.

    Lemma 2.2. Let fL1(0,T;R) [33]. The unique solution of the fractional order problem

    {βtu(t)+au(t)=f(t),a0, t0,u(0)=u0, u(0)=u1,

    is give by

    u(t)=Eβ,1(atβ)u0+tEβ,2(atβ)u1+t0(ts)β1Eβ,β(a(ts)β)f(s)ds.

    In particular,

    u(t)=cos(at)u0+1asin(at)u1+1at0sin(a(ts))f(s)ds,

    which is the unique solution to the corresponding classical wave equation, i.e., β=2.

    In this section, we are concerned with the following linear Cauchy problem

    {βtu(t,x)Δu(t,x)=f(t,x),t>0, xRN,u(0,x)=ϕ(x), tu(0,x)=ψ(x). (3.1)

    Without loss of generality, the solutions in this paper are defined as mild solutions associated with the corresponding initial data.

    We first establish the solution representation of linear problem (3.1). Let u satisfies (3.1), taking the Fourier transform of both sides in (3.1) with respect to xRN, we obtain

    {βtˆu(t,ξ)+|ξ|2ˆu(t,ξ)=ˆf(t,ξ),t>0,ˆu(0,ξ)=ˆϕ(ξ), tˆu(0,ξ)=ˆψ(ξ).

    It follows from [4,(1.100)] that

    tEβ,2(tβ|ξ|2)=1Γ(2β)t0(ts)1βEβ,β(sβ|ξ|2)sβ1ds.

    Therefore, by virtue of Lemma 2.2, we get

    ˆu(t,ξ)=ˆφ(t,ξ)ˆϕ(ξ)+(ˆϑ(,ξ)g2β)(t)ˆψ(ξ)+(ˆϑ(,ξ)ˆf)(t),

    where

    ˆφ(t,ξ)=Eβ,1(tβ|ξ|2),ˆϑ(t,ξ)=tβ1Eβ,β(tβ|ξ|2).

    By using the inverse Fourier transform, we get

    u(t,x)=RNφ(t,xy)ϕ(y)dy+t0RNg2β(ts)ϑ(s,xy)ψ(y)dyds+t0RNϑ(ts,xy)f(s,y)dyds,

    where

    φ(t,x)=(2π)N/2RNeixξEβ,1(tβ|ξ|2)dξ,ϑ(t,x)=(2π)N/2RNeixξtβ1Eβ,β(tβ|ξ|2)dξ.

    On the other hand, set σ=β/2(1/2,1), it follows from Lemma 2.1 that

    φ(t,x)=(2π)N/20RNeixξMσ(θ)cos(tσθ|ξ|)dξdθ,

    and

    ϑ(t,x)=tσ1(2π)N/20RNeixξσθMσ(θ)sin(tσθ|ξ|)|ξ|dξdθ.

    Let

    ˙K(t)v=F1[cos(t|ξ|)ˆv(ξ)],K(t)v=F1[sin(t|ξ|)|ξ|ˆv(ξ)],

    and

    Sσ(t)v=σtσ10θMσ(θ)K(tσθ)vdθ.

    Rewriting u(t) for the function u(t,), we get an equivalent integral representation for problem (3.1) by

    u(t)=Cσ(t)ϕ+Pσ(t)ψ+t0Sσ(ts)f(s)ds, (3.2)

    where solution operators Cσ() and Pσ() are defined by

    Cσ(t)ϕ=0Mσ(θ)˙K(tσθ)ϕdθ,Pσ(t)ψ=(g22σSσ)(t)ψ.

    Let α(r)=121r for r[2,], and

    β(r)=N+12α(r),γ(r)=(N1)α(r),δ(r)=Nα(r).

    Let us recall the following two results in [34,35], which play a key role in proving the general results on the solution operators.

    Lemma 3.1. Let 2p< and 2β(p)ν2δ(p). Then for t0, it follows that

    F1[|ξ|νeit|ξ|ˆv(ξ)]Lp(RN)|t|ν2δ(p)vLp(RN).

    Lemma 3.2. Let 2p< and 2β(p)ν2δ(p), 0μs+ν. Then for 1q, t0, it follows that

    F1[|ξ|μeit|ξ|ˆv(ξ)]Bsp,q(RN)|t|ν2δ(p)vBs+νμp,q(RN).

    In the sequel, we set ϖ=(Δ)12 and U(t)=exp(iϖt)=F1[exp(i|ξ|t)F], so that K(t)=ϖ1sin(ϖt), ˙K(t)=cos(ϖt). Hence, it follows that

    K(t)=ϖ1U(t)U(t)2i,˙K(t)=U(t)+U(t)2.

    Lemma 3.3. Let N2, 2N/(N1)p2(N+1)/(N1), then Sσ(t):Lp(RN)Lp(RN) and moreover

    Sσ(t)vLp(RN)t2σ2σδ(p)1vLp(RN),vLp(RN),  t>0.

    Proof. Obviously, the condition 2NN1p2(N+1)N1 for N2 implies that 1/2δ(p)N/(N+1). Hence, it follows from Lemma 3.1 that

    K(t)vLp(RN)t12δ(p)vLp(RN).

    By the definition of Sσ(t), and (2.1) we obtain

    Sσ(t)vLp(RN)σtσ10θMσ(θ)K(tσθ)vLp(RN)dθσtσ1+σ(12δ(p))0θ22δ(p)Mσ(θ)dθvLp(RN)t2σ2σδ(p)1vLp(RN).

    Consequently, we get the desired inequality.

    Lemma 3.4. Let 2p<, 1q, sR, t>0.

    If (s)(2δ(p)1)(2β(p))ν2δ(p), then

    Cσ(t)vBsp,q(RN)tσ(ν2δ(p))vBs+νp,q(RN).

    If (1s)(2δ(p)2)(2β(p))ν2δ(p), then

    Sσ(t)vBsp,q(RN)tσ(ν2δ(p)+1)1vBs+ν1p,q(RN).

    Proof. From Lemma 3.2, for t>0 we have the following estimates

    ˙K(t)vBsp,q(RN)tν2δ(p)vBs+νp,q(RN),0s+ν,
    K(t)vBsp,q(RN)tν2δ(p)vBs+ν1p,q(RN),1s+ν.

    Therefore, using the same argument as employed in Lemma 3.3, we obtain the desired results.

    Let σ=β/2 for β(1,2). We now introduce an operator Qσ defined by

    (Qσf)(t)=t0Sσ(ts)f(s)ds.

    In order to obtain the existence of L2-solutions, we need the following lemma.

    Lemma 3.5. For each hLp(0,T;X) with 1p<+ [36], we have

    limτ0T0h(t+τ)h(t)pXdt=0,

    where we suppose that h(s)=0 for s not belonging to [0,T].

    Lemma 3.6. For any q and μ with 1<q2 and μ=N(1/q1/21/N), N1, let fLr(0,T;Hμ,q(RN)), then

    QσfL(0,T;L2(RN))fLr(0,T;Hμ,q(RN)),

    for r>1/σ. Furthermore, let q=2N/(N+2) for N3, and fLr(0,T;Lq(RN)), then

    QσfL(0,T;L2(RN))fLr(0,T;Lq(RN)).

    Moreover the operator Qσ maps Lr(0,T;H1(RN)) into C([0,T];L2(RN)).

    Proof. The inequality |sinα|1|α| for any αR implies

    |(sin(t|ξ|)ξ)/|ξ||(1(t|ξ|))ξ/|ξ|(1+t)(1|ξ|)ξ/|ξ|2(1+t), (3.3)

    where ξ=1+|ξ|2, for t0, ξRN. Let g(t,s,ξ)=sin((ts)σθ|ξ|)ˆf(s,ξ)/|ξ| and y(t,x)=x1ˆf(s,x), for s(0,t), ξ,xRN. It is clear by (3.3) that

    |g(t,s,ξ)|2(1+(ts)σθ)|y(s,ξ)|,for s(0,t), ξRN.

    Then it follows from the Plancherel theorem (see e.g. [37]) that

    ˇg(t,s,)L2(RN)=g(t,s,)L2(RN)2(1+(ts)σθ)y(s,)L2(RN)=2(1+(ts)σθ)ˇy(s,)L2(RN).

    Therefore, we have

    (Qσf)(t)L2(RN)t0Sσ(ts)f(s,)L2(RN)dst00σ(ts)σ1θMσ(θ)ˇg(t,s,)L2(RN)dθds2t00σ(ts)σ1θMσ(θ)(1+(ts)σθ)ˇy(s,)L2(RN)dθds.

    Due to ˇy(s,)L2(RN)=F1[ξ1ˆf(s,ξ)]L2(RN)=f(s,)H1(RN), in view of (2.1) and Hölder inequality, for r>1/σ we get

    (Qσf)(t)L2(RN)2t00σ(ts)σ1θMσ(θ)f(s,)H1(RN)dθds+2t00σ(ts)2σ1θ2Mσ(θ)f(s,)H1(RN)dθds=2t0gσ(ts)f(s,)H1(RN)ds+2t0g2σ(ts)f(s,)H1(RN)dsCfLr(0,T;H1(RN)), (3.4)

    where C depends on σ,r,N and T.

    Now, let us show the first estimate. Due to the embedding Hs,p(RN)Hs1,p1(RN) for 1<pp1<, s,s1R, and sN/p=s1N/p1, (see e.g., [31,32]) we know that Hμ,q(RN)H1(RN) for μ=N(1/q1/21/N). This means that

    (Qσf)(t)L2(RN)fLr(0,T;Hμ,q(RN)).

    Hence, the first estimate holds. On the other hand, since Bs2,2(RN)=Hs,2(RN) for sR, recall the embedding Hs,q(RN)Bsq,2(RN) for 1<q2 and the embedding (see e.g., [31,32])

    Bs0p0,q0(RN)Bs1p1,q1(RN),  for  s0N/p0=s1N/p1, (3.5)

    for any s0,s1R, 1p0p1, 1q0q1, we have

    B0q,2(RN)B12,2(RN),for q=2NN+2,

    by virtue of H0,q(RN)B0q,2(RN), and H0,q(RN)=Lq(RN) for q1, we obtain the embedding Lq(RN)H1(RN) when q=2N/(N+2). These means that

    (Qσf)(t)L2(RN)fLr(0,T;Lq(RN)).

    Hence, the second estimate holds.

    Finally, in order to obtain the conclusion that the operator Qσ maps Lr(0,T;H1(RN)) into C([0,T];L2(RN)), by (3.4) it suffices to prove the continuity of operator Qσ for any fLr(0,T;H1(RN)), i.e., we next to check that for 0t<t+hT

    (Qσf)(t+h)(Qσf)(t)L2(RN)0,as h0.

    In fact, we first have

    (Qσf)(t+h)(Qσf)(t)L2(RN)t+htSσ(t+hs)f(s,)dsL2(RN)+t00σ((t+hs)σ1(ts)σ1)θMσ(θ)ˇg(t+h,s,)dθdsL2(RN)+t00σ(ts)σ1θMσ(θ)(ˇg(t+h,s,)ˇg(t,s,))dθdsL2(RN):=I1+I2+I3.

    Obviously, applying (2.1) and Hölder inequality, it follows that

    I12t+ht0σ(t+hs)σ1θMσ(θ)f(s,)H1(RN)dθds+2t+ht0σ(t+hs)2σ1θ2Mσ(θ)f(s,)H1(RN)dθds=2t+htgσ(t+hs)f(s,)H1(RN)ds+2t+htg2σ(t+hs)f(s,)H1(RN)dshσ1/rfLr(0,T;H1(RN))+h2σ1/rfLr(0,T;H1(RN))0,as h0.

    For the second term I2, similarly to (3.4) we have

    I22t00σ|(t+hs)σ1(ts)σ1|θMσ(θ)f(s,)H1(RN)dθds+2t00σ|(t+hs)σ1(ts)σ1|(t+hs)σθ2Mσ(θ)f(s,)H1(RN)dθds=Cht0|(t+hs)σ1(ts)σ1|f(s,)H1(RN)dsCh(t0|(t+hs)σ1(ts)σ1|r/(r1)ds)11/rfLr(0,T;H1(RN)),

    where Ch=(2/Γ(σ)+2(T+h)σ/Γ(2σ)). Using the Lebesgue dominated convergence theorem and Lemma 3.5 we find that I20 as h0.

    For estimating the third term I3, by virtue of (3.3), we first have

    ˇg(t+h,s,)ˇg(t,s,)L2(RN)22(1+(t+hs)σθ)f(s,)H1(RN),

    which means that

    I3t00σ(ts)σ1θMσ(θ)ˇg(t+h,s,)ˇg(t,s,)L2(RN)dθds22t00σ(ts)σ1θMσ(θ)f(s,)H1(RN)dθds+22t00σ(ts)σ1(t+hs)σθ2Mσ(θ)f(s,)H1(RN)dθdsfLr(0,T;H1(RN)).

    Hence, by the Lebesgue dominated convergence theorem, we conclude that I30 as h0. Similarly, for any 0th<tT, it is not difficult to verify that (Qσf)(t)(Qσf)(th)L2(RN)0, as h0. Thus, the proof is completed.

    Lemma 3.7. For any sR, operators Cσ() and Pσ() satisfy

    Cσ()ϕC([0,T];Hs(RN))ϕHs(RN),  Pσ()ψC([0,T];Hs(RN))ψHs1(RN),

    for any (ϕ,ψ)Hs(RN)×Hs1(RN).

    Proof. By virtue of |cos(t|x|)|1 for all t0, xRN, it is easy to get ˙K(t)ϕHs(RN)ϕHs(RN). In fact, for any ϕHs(RN), we have

    ˙K(t)ϕHs(RN)=F1[cos(t||)ˆϕ]Hs(RN)=F1[(1+||2)s/2cos(t||)ˆϕ]L2(RN).

    The Plancherel theorem implies

    F1[(1+||2)s/2cos(t||)ˆϕ]L2(RN)=(1+||2)s/2cos(t||)ˆϕL2(RN)(1+||2)s/2ˆϕL2(RN)=F1[(1+||2)s/2ˆϕ]L2(RN),

    which means that ˙K(t)ϕHs(RN)ϕHs(RN). In addition, by virtue of the inequality |sin(t|x|)|t|x|, for all t0, xRN, as repeating the above processes, by (3.3) it is easy to check that K(t)ψHs(RN)2(1+t)ψHs1(RN) for any ψHs1(RN).

    Let us show that Cσ(t)ϕHs(RN)ϕHs(RN). In fact, from the definition of operator Cσ(), we have

    Cσ(t)ϕHs(RN)0Mσ(θ)˙K(tσθ)ϕHs(RN)dθϕHs(RN),

    where we have used the identity (2.1). Moreover, from the definition of operator Sσ() and the semigroup (gagb)(t)=ga+b(t) for a,b>0, t>0, we have

    Pσ(t)ψHs(RN)t0g22σ(ts)Sσ(s)ψHs(RN)dst00g22σ(ts)σsσ1θMσ(θ)K(sσθ)ψHs(RN)dθds2t00g22σ(ts)σsσ1(1+sσθ)θMσ(θ)ψHs1(RN)dθds=2((g22σgσ)(t)+(g22σg2σ)(t))ψHs1(RN)ψHs1(RN),

    where (g22σgσ)(t)+(g22σg2σ)(t)g2σ(T)+g2(T). Hence, it yields Pσ(t)ψHs(RN)ψHs1(RN). To end this proof, it suffices to check the continuity of Cσ(t)ϕ and Pσ(t)ψ.

    By the continuity of cos(t|ξ|), for h>0 and 0t<t+hT, by the Plancherel theorem we know that

    ˙K((t+h)σθ)ϕ˙K(tσθ)ϕHs(RN)=F1[s(cos((t+h)σθ||)cos(tσθ||))ˆϕ]L2(RN)=s(cos((t+h)σθ||)cos(tσθ||))ˆϕL2(RN)2sˆϕL2(RN)=2ϕHs(RN).

    Hence, passing to the Fourier representation and the Lebesgue dominated convergence theorem, we have the pointwise convergence

    ˙K((t+h)σθ)ϕ˙K(tσθ)ϕHs(RN)0,as h0, a.e.  θ(0,).

    On the other hand, by (2.1) we have

    is integrable for a.e. , hence Lebesgue dominated convergence theorem implies

    This means that . Furthermore, as repeating the above processes, we also get the continuity of . Hence, . The proof is completed.

    Remark 3.1. Obviously, in view of the inequality , for all , , from the same way as in Lemma 3.7, we get,

    By using Lemma 3.6 and Lemma 3.7, it is not difficult to obtain the existence theorem to linear problem (3.1).

    Theorem 3.1. Let . Given for , let and , for any and satisfying and , , then there exists a unique solution to the linear problem (3.1), and moreover

    Let for , if , then

    In the sequel, we consider the global existence to the linear Cauchy problem (3.1).

    Theorem 3.2. Given , for . Let , for and , where the Banach space

    equipped with its natural norm . Then there exists a unique solution to the linear problem (3.1), and moreover

    (3.6)

    Proof. Observe that, for , from Lemma 3.7, . Moreover, for any , Lemma 3.4 implies

    which means that . Hence, we have

    where we have used the semigroup for . Similarly to Lemma 3.6 and Lemma 3.7, the continuity is easy to check, where we can use the Plancherel theorem and Lebesgue dominated convergence theorem. Consequently, there exists a solution satisfying (3.2) and its values lie in , and then (3.6) holds. Moreover, the uniqueness follows (3.6). The proof is completed.

    In this section, we focus on the well-posedness results of the semilinear problem, we first establish a local well-posed result of -solutions that also belong to the setting of , furthermore, by a similar way in Theorem 3.2, another conclusion will be given in the framework of . In the sequel, for a given semilinear function, we obtain the well-posedness results in the setting of Besov space .

    Theorem 4.1. Let and for any . Assume that

    where index satisfying

    For every , there exist and constant such that

    for all with . Let be an element to the admissible set

    for Then there exists a unique mild solutionof the problem (1.1)–(1.2) for some . Moreover, depends continuously on in the following sense. If in and in and if denotes the solution of problem (1.1)-(1.2) with the initial value , then for all sufficiently large , converges to in .

    Proof. Let for . We want to construct a local (in ) solution to the integral equation

    By applying Lemma 3.6, Lemma 3.7, and Remark 3.1, it is clear that is well defined. We next shall use a fixed point argument to verify this proof. Fixed and set a space by

    where is the distance to the space given by

    Obviously, is a complete metric space.

    For and every , from the assumption of nonlinearity , by the trigonometric inequality we first have

    Therefore, for , Hölder inequality yields

    Similarly, for , we have

    which, by Hölder inequality and Minkowski inequality, leads to

    (4.1)

    Next, we obtain the existence and uniqueness results for small. By Lemma 3.3, for and , we have

    Observe that the embedding for , , we have

    Therefore, we have

    On the other hand, by Lemma 3.6, for any , we have

    Therefore, there exists a constant such that

    Fixed satisfying , let be small enough such that

    (4.2)

    and

    Hence, it follows that for any . Moreover, from Lemma 3.6 we deduce

    where , for and for . Hence, by selecting small enough so that (4.2) holds, by virtue of (4.1), we have

    for all . Since

    for small enough so that (4.2) holds, by virtue of (4.1), it follows that

    Consequently, is a strict contraction on . From the similar proof of continuity in Theorem 3.1 taking on , it follows that has a fixed point , which is the unique mild solution of problem (1.1)–(1.2).

    For the choice of (independent to and ), as before, is determined only by the size of the norm of initial data. Hence and are independent of for sufficiently large. Suppose in and in when . Now, let be large enough, then

    By the same argument, one can conclude that

    Then, (4.1) implies that

    Let be chosen so small such that (4.2) holds, then

    Consequently, we deduce that as . The proof is completed.

    Remark 4.1. From the above theorem, we have the following remarks:

    The admissible set of is not empty. Indeed, for , , and taking initial values , for a suitable semilinear function satisfying the assumptions in Theorem 4.1, likely for , it follows that for .

    Let and satisfy the assumptions of Theorem 4.1, noting that if , then the restrictions in the admissible set of reduce to , or if and , then the restrictions in the admissible set of reduce to .

    By the embedding for , the requirement implies that the conclusion fails for , and thus the assumption is needed in the initial value conditions.

    Noting that, by virtue of the critical embedding , for , , we obtain a weaken requirement of index in Theorem 4.1.

    Corollary 4.1. Let and . Assume that

    where index satisfying

    For every , there exist and constant such that

    for all with . Let be an element to the admissible set

    Then the problem (1.1)–(1.2) is local well-posed on .

    By using the embedding

    one can prove the following result by employing the arguments used in the proof of Theorem 4.1.

    Corollary 4.2. Let . Assume that for every , there exists such that

    for all and that of , . Then for , problem (1.1)–(1.2) is local well-posed on for some , where is the metric space given by

    equipped with the distance

    In the sequel, we consider a semilinear function of the form for and for , a well-posed result on Besov setting is also established. In order to complete the proof, we need the following result [38].

    Lemma 4.1. Let for and for . If , , then

    and

    for any .

    Proof. Noting that

    we obtain by Hölder inequality and the embedding that

    and

    In view of the inequality

    and the interpolation property , the desired inequalities follow.

    Theorem 4.2. Let , and for , . Let

    given .Moreover, let being an element tothe set

    (4.3)

    Then the problem (1.1)–(1.2) is local well-posed on .

    Proof. Following the method of proof for Theorem 4.1, we just need to construct a local solution to the operator equation for in a suitable ball in , where the ball is defined by

    with the radius . Note that this space is not trivial. Indeed, for , by virtue of Lemma 3.4, and the embedding (3.5) and for , we have

    which shows that . Similarly, by we also get . Thus, is in if and is small enough. Endowed with the metric

    then is a complete metric space. Indeed, since is reflexive, the closed ball of radius is weakly compact, for details, see [38].

    From Lemma 4.1, we get for all . Thus, it remains to consider the case for some . Noting that from the requirements of index , it yields , consider any , then it follows from (4.3) that

    Noting that

    we obtain

    On the other hand, from Lemma 4.1, for any , we get

    Therefore, we have

    This means that there exists a constant such that

    and

    Hence, fixed , let be small enough such that

    Then maps into itself and we obtain

    Thus, there exists a unique solution of problem (1.1)–(1.2). The remaining proof is similar to that of Theorem 4.1. So we omit its details. The proof is completed.

    Remark 4.2. Observe that, the embedding , Lemma 3.4 yields

    which belongs to . Hence, it shall possess a decay rate , which implies that the solution does not belong to .

    Concerning with Remark 4.2, in the sequel, we establish the global well-posed result for a special initial data.

    Theorem 4.3. Let , , , and for .Given with for some and .Then the problem (1.1)–(1.2) is global well-posed on , where is the metric space given by

    equipped with the distance

    Proof. Let for . We next verity the operator maps into itself. Indeed, for , by virtue of Lemma 3.4, we have

    where we have used the embedding for , . Therefore, there exists a constant such that

    Taking for , due to the Fourier representation of operators and the Lebesgue dominated convergence theorem, the proof of the continuity of is similar to Lemma 3.6. Hence, we deduce that for any .

    Next, we show that is a contraction on . Indeed, for any , combined the requirement of and Lemma 3.3 imply

    Lemma 4.1 shows that

    Therefore, there exists a constant for such that

    Consequently, is a strict contraction on . This means that has a unique fixed point . The proof is completed.

    In this paper, we proved some well-posedness results for linear and semilinear time fractional wave equations, which are also called super-diffusive equations. Under the probability density function and wave operators, we construct the solution operators that are differential to the references therein, which are also useful to establish the local well-posedness of -solutions as well as the local well-posedness on Besov space. Moreover, based on the standard fixed point arguments, the initial data and are taking in the more regularity fractional Sobolev spaces, respectively. Finally, we also establish the global existence results for a linear and a spacial semilinear fractional Cauchy problems.

    The work was supported by National Natural Science Foundation of China (Nos. 12071396, 12101142).

    The authors declare there is no conflicts of interest.



    [1] G. M. Zaslavsky, Fractional kinetic equation for Hamiltonian chaos, Phys. D., 76 (1994), 110–122. https://doi.org/10.1016/0167-2789(94)90254-2 doi: 10.1016/0167-2789(94)90254-2
    [2] T. Langlands, B. Henry, S. Wearne, Fractional cable equation models for anomalous electrodiffusion in nerve cells: infinite domain solutions, J. Math. Biol., 59 (2009), 761–808. https://doi.org/10.1007/s00285-009-0251-1 doi: 10.1007/s00285-009-0251-1
    [3] T. Langlands, B. Henry, S. Wearne, Fractional cable equation models for anomalous electrodiffusion in nerve cells: finite domain solutions, SIAM J. Appl. Math., 71 (2011), 1168–1203. https://doi.org/10.1137/090775920 doi: 10.1137/090775920
    [4] I. Podlubny, Fractional Differential Equations, Academic Press, San Diego, 1999.
    [5] I. Podlubny, Fractional-order systems and -controllers, IEEE Trans. Auto. Control, 44 (1999), 208–214. https://doi.org/10.1109/9.739144 doi: 10.1109/9.739144
    [6] M. D. Paola, A. Pirrotta, A. Valenza, Visco-elastic behavior through fractional calculus: an easier method for best fitting experimental results, Mech. Mater., 43 (2011), 799–806. https://doi.org/10.1016/j.mechmat.2011.08.016 doi: 10.1016/j.mechmat.2011.08.016
    [7] F. Mainardi, Fractional calculus and waves in linear viscoelasticity, in An Introduction to Mathematical Models, Imperial College Press, London, (2010), 368. https://doi.org/10.1142/p614
    [8] L. Chen, Nonlinear stochastic time-fractional diffusion equations on : Moments, Hölder regularity and intermittency, Tran. Am. Math. Soc., 369 (2017), 8497–8535. https://doi.org/10.1090/tran/6951 doi: 10.1090/tran/6951
    [9] J. Kemppainen, J. Siljander, R. Zacher, Representation of solutions and large-time behavior for fully nonlocal diffusion equations, J. Differ. Equations, 263 (2017), 149–201. https://doi.org/10.1016/j.jde.2017.02.030 doi: 10.1016/j.jde.2017.02.030
    [10] R. Zacher, A De Giorgi-Nash type theorem for time fractional diffusion equations, Math. Ann., 356 (2013), 99–146. https://doi.org/10.1007/s00208-012-0834-9 doi: 10.1007/s00208-012-0834-9
    [11] Y. Zhou, J. W. He, B. Ahmad, N. H. Tuan, Existence and regularity results of a backward problem for fractional diffusion equations, Math. Methods Appl. Sci., 42 (2019), 6775–6790. https://doi.org/10.1002/mma.5781 doi: 10.1002/mma.5781
    [12] J. R. Wang, M. Feckan, Y. Zhou, Fractional order differential switched systems with coupled nonlocal initial and impulsive conditions, Bull. Sci. Math., 141 (2017), 727–746. https://doi.org/10.1016/j.bulsci.2017.07.007 doi: 10.1016/j.bulsci.2017.07.007
    [13] Y. Zhou, Infinite interval problems for fractional evolution equations, Mathematics, 10 (2022), 900. https://doi.org/10.3390/math10060900 doi: 10.3390/math10060900
    [14] Y. Zhou, B. Ahmad, A. Alsaedi, Existence of nonoscillatory solutions for fractional neutral differential equations, Appl. Math. Lett., 72 (2017), 70–74. https://doi.org/10.1016/j.aml.2017.04.016 doi: 10.1016/j.aml.2017.04.016
    [15] Y. Zhou, J. N. Wang, The nonlinear Rayleigh-Stokes problem with Riemann- Liouville fractional derivative, Math. Meth. Appl. Sci., 44 (2021), 2431–2438. https://doi.org/10.1002/mma.5926 doi: 10.1002/mma.5926
    [16] R. Metzler, J. Klafter, The random walk's guide to anomalous diffusion: a fractional dynamics approach, Phys. Rep., 339 (2000), 1–77. https://doi.org/10.1016/S0370-1573(00)00070-3 doi: 10.1016/S0370-1573(00)00070-3
    [17] T. M. Atanacković, S. Pilipović, B. Stanković, D. Zorica, Fractional Calculus with Applications in Mechanics, Wiley-ISTE, 2014.
    [18] Y. Kian, M. Yamamoto, On existence and uniqueness of solutions for semilinear fractional wave equations, Fract. Calc. Appl. Anal., 20 (2017), 117–138. https://doi.org/10.1515/fca-2017-0006 doi: 10.1515/fca-2017-0006
    [19] E. Alvarez, G. C. Gal, V. Keyantuo, M. Warma, Well-posedness results for a class of semi-linear super-diffusive equations, Nonlinear Anal., 181 (2019), 24–61. https://doi.org/10.1016/j.na.2018.10.016 doi: 10.1016/j.na.2018.10.016
    [20] E. Otárola, A. J. Salgado, Regularity of solutions to space-time fractional wave equations: a PDE approach, Fract. Calc. Appl. Anal., 21 (2018), 1262–1293. https://doi.org/10.1515/fca-2018-0067 doi: 10.1515/fca-2018-0067
    [21] Y. Zhou, J.W. He, Well-posedness and regularity for fractional damped wave equations, Monatsh. Math., 194 (2021), 425–458. https://doi.org/10.1007/s00605-020-01476-7 doi: 10.1007/s00605-020-01476-7
    [22] V. V. Au, N. D. Phuong, N. H. Tuan, Y. Zhou, Some regularization methods for a class of nonlinear fractional evolution equations, Comput. Math. Appl., 78 (2019), 1752–1771. https://doi.org/10.1016/j.camwa.2019.02.037 doi: 10.1016/j.camwa.2019.02.037
    [23] Y. Li, Y. Wang, W. Deng, Galerkin finite element approximations for stochastic space-time fractional wave equations, SIAM J. Numer. Anal., 55 (2017), 3173–3202. https://doi.org/10.1137/16M1096451 doi: 10.1137/16M1096451
    [24] M. M. Meerschaert, R. L. Schilling, A. Sikorskii, Stochastic solutions for fractional wave equations, Nonlinear Dyn., 80 (2015), 1685–1695. https://doi.org/10.1007/s11071-014-1299-z doi: 10.1007/s11071-014-1299-z
    [25] N. H. Tuan, V. Au, L. N. Huynh, Y. Zhou, Regularization of a backward problem for the inhomogeneous time-fractional wave equation, Math. Methods Appl. Sci., 43 (2020), 5450–5463. https://doi.org/10.1002/mma.6285 doi: 10.1002/mma.6285
    [26] A. V. Van, K. V. H. Thi, A. T. Nguyen, On a class of semilinear nonclassical fractional wave equations with logarithmic nonlinearity, Math. Methods Appl. Sci., 44 (2021), 11022–11045. https://doi.org/10.1002/mma.7466 doi: 10.1002/mma.7466
    [27] M. F. de Alemida, J. C. P. Precioso, Existence and symmetries of solutions in Besov-Morrey spaces for a semilinear heat-wave type equation, J. Math. Anal. Appl., 432 (2015), 338–355. https://doi.org/10.1016/j.jmaa.2015.06.044 doi: 10.1016/j.jmaa.2015.06.044
    [28] M. F. de Alemida, A. Viana, Self-similar solutions for a superdiffusive heat equation with gradient nonlinearity, Elec. J. Differ. Equations, 2016 (2016), 250.
    [29] Q. Zhang, Y. Li, Global well-posedness and blow-up solutions of the Cauchy problem for a time-fractional superdiffusion equation, J. Evol. Equations, 19 (2019), 271–303. https://doi.org/10.1007/s00028-018-0475-x doi: 10.1007/s00028-018-0475-x
    [30] J. D. Djida, A. Fernandez, I. Area, Well-posedness results for fractional semi-linear wave equations, Discrete Cont. Dyn-B, 25 (2020), 569–597. https://doi.org/10.3934/dcdsb.2019255 doi: 10.3934/dcdsb.2019255
    [31] J. Bergh, J. Löfström, Interpolation Spaces: An Introduction, Springer-Verlag, Berlin, 1976. https://doi.org/10.1007/978-3-642-66451-9
    [32] T. Cazenave, Semilinear Schrödinger equations, Am. Math. Soc., 10 (2003). https://doi.org/10.1090/cln/010 doi: 10.1090/cln/010
    [33] A. A. Kilbas, H. M. Srivastava, J. J. Trujillo, Theory and Applications of Fractional Differential Equations, Elsevier Science Limited, Amsterdam, 2006.
    [34] H. Pecher, Local solutions of semilinear wave equations in , Math. Meth. Appl. Sci., 19 (1996), 145–170. https://doi.org/10.1002/(SICI)1099-1476(19960125)19:2<145::AID-MMA767>3.0.CO;2-M doi: 10.1002/(SICI)1099-1476(19960125)19:2<145::AID-MMA767>3.0.CO;2-M
    [35] H. Pecher, -Abschätzungen und klassische Lösungen für nichtlineare Wellengleichungen. Ⅰ, Math. Z. 150 (1976), 159–183. https://doi.org/10.1007/BF01215233 doi: 10.1007/BF01215233
    [36] E. Zeidler, Nonlinear Functional Analysis and its Application, Springer-Verlag, New York, 1990. https://doi.org/10.1007/978-1-4612-0981-2
    [37] L. C. Evans, Partial Differential Equations, 2nd Edition, American Mathematical Society, 2010.
    [38] T. Cazenave, B. Weissler, The cauchy problem for the critical nonlinear Schrödinger equation in , Nonlinear Anal., 14 (1990), 807–836. https://doi.org/10.1016/0362-546X(90)90023-A doi: 10.1016/0362-546X(90)90023-A
  • This article has been cited by:

    1. Renhai Wang, Nguyen Huu Can, Anh Tuan Nguyen, Nguyen Huy Tuan, Local and global existence of solutions to a time-fractional wave equation with an exponential growth, 2023, 118, 10075704, 107050, 10.1016/j.cnsns.2022.107050
    2. Xuan-Xuan Xi, Yong Zhou, Mimi Hou, Well-Posedness of Mild Solutions for Superdiffusion Equations with Spatial Nonlocal Operators, 2024, 23, 1575-5460, 10.1007/s12346-024-01084-y
    3. Yubin Liu, Li Peng, The well-posedness analysis in Besov-type spaces for multi-term time-fractional wave equations, 2024, 1311-0454, 10.1007/s13540-024-00348-3
  • Reader Comments
  • © 2022 the Author(s), licensee AIMS Press. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0)
通讯作者: 陈斌, bchen63@163.com
  • 1. 

    沈阳化工大学材料科学与工程学院 沈阳 110142

  1. 本站搜索
  2. 百度学术搜索
  3. 万方数据库搜索
  4. CNKI搜索

Metrics

Article views(1969) PDF downloads(140) Cited by(3)

Other Articles By Authors

/

DownLoad:  Full-Size Img  PowerPoint
Return
Return

Catalog