
a) The perforated strip
We consider a one-dimensional free boundary problem describing the migration of diffusants into rubber. In our setting, the free boundary represents the position of the front delimitating the diffusant region. The growth rate of this region is described by an ordinary differential equation that includes the effect of breaking the growth of the diffusant region. In this specific context, the breaking mechanism is should be perceived as a non-dissipative way of describing eventual hyperelastic response to a too fast diffusion penetration. In recent works, we considered a similar class of free boundary problems modeling diffusants penetration in rubbers, but without attempting to deal with the possibility of breaking or accelerating the occurring free boundaries. For simplified settings, we were able to show the global existence and uniqueness as well as the large time behavior of the corresponding solutions to our formulations. Since here the breaking effect is contained in the free boundary condition, our previous results are not anymore applicable. The main mathematical obstacle in ensuring the existence of a solution is the non-monotonic structure of the free boundary. In this paper, we establish the existence and uniqueness of a weak solution to the free boundary problem with breaking effect and give explicitly the maximum value that the free boundary can reach.
Citation: Kota Kumazaki, Toyohiko Aiki, Adrian Muntean. Local existence of a solution to a free boundary problem describing migration into rubber with a breaking effect[J]. Networks and Heterogeneous Media, 2023, 18(1): 80-108. doi: 10.3934/nhm.2023004
[1] | Sergei A. Nazarov, Rafael Orive-Illera, María-Eugenia Pérez-Martínez . Asymptotic structure of the spectrum in a Dirichlet-strip with double periodic perforations. Networks and Heterogeneous Media, 2019, 14(4): 733-757. doi: 10.3934/nhm.2019029 |
[2] | Valeria Chiado Piat, Sergey S. Nazarov, Andrey Piatnitski . Steklov problems in perforated domains with a coefficient of indefinite sign. Networks and Heterogeneous Media, 2012, 7(1): 151-178. doi: 10.3934/nhm.2012.7.151 |
[3] | Luis Caffarelli, Antoine Mellet . Random homogenization of fractional obstacle problems. Networks and Heterogeneous Media, 2008, 3(3): 523-554. doi: 10.3934/nhm.2008.3.523 |
[4] | Günter Leugering, Sergei A. Nazarov, Jari Taskinen . The band-gap structure of the spectrum in a periodic medium of masonry type. Networks and Heterogeneous Media, 2020, 15(4): 555-580. doi: 10.3934/nhm.2020014 |
[5] | Vivek Tewary . Combined effects of homogenization and singular perturbations: A bloch wave approach. Networks and Heterogeneous Media, 2021, 16(3): 427-458. doi: 10.3934/nhm.2021012 |
[6] | Chaoqun Huang, Nung Kwan Yip . Singular perturbation and bifurcation of diffuse transition layers in inhomogeneous media, part I. Networks and Heterogeneous Media, 2013, 8(4): 1009-1034. doi: 10.3934/nhm.2013.8.1009 |
[7] | Patrizia Donato, Florian Gaveau . Homogenization and correctors for the wave equation in non periodic perforated domains. Networks and Heterogeneous Media, 2008, 3(1): 97-124. doi: 10.3934/nhm.2008.3.97 |
[8] | Martin Heida . Stochastic homogenization on perforated domains III–General estimates for stationary ergodic random connected Lipschitz domains. Networks and Heterogeneous Media, 2023, 18(4): 1410-1433. doi: 10.3934/nhm.2023062 |
[9] | Carlos Conca, Luis Friz, Jaime H. Ortega . Direct integral decomposition for periodic function spaces and application to Bloch waves. Networks and Heterogeneous Media, 2008, 3(3): 555-566. doi: 10.3934/nhm.2008.3.555 |
[10] | Oleh Krehel, Toyohiko Aiki, Adrian Muntean . Homogenization of a thermo-diffusion system with Smoluchowski interactions. Networks and Heterogeneous Media, 2014, 9(4): 739-762. doi: 10.3934/nhm.2014.9.739 |
We consider a one-dimensional free boundary problem describing the migration of diffusants into rubber. In our setting, the free boundary represents the position of the front delimitating the diffusant region. The growth rate of this region is described by an ordinary differential equation that includes the effect of breaking the growth of the diffusant region. In this specific context, the breaking mechanism is should be perceived as a non-dissipative way of describing eventual hyperelastic response to a too fast diffusion penetration. In recent works, we considered a similar class of free boundary problems modeling diffusants penetration in rubbers, but without attempting to deal with the possibility of breaking or accelerating the occurring free boundaries. For simplified settings, we were able to show the global existence and uniqueness as well as the large time behavior of the corresponding solutions to our formulations. Since here the breaking effect is contained in the free boundary condition, our previous results are not anymore applicable. The main mathematical obstacle in ensuring the existence of a solution is the non-monotonic structure of the free boundary. In this paper, we establish the existence and uniqueness of a weak solution to the free boundary problem with breaking effect and give explicitly the maximum value that the free boundary can reach.
In this paper we consider a spectral problem for the Laplace operator in an unbounded strip
a) The perforated strip
We provide asymptotic formulas for the endpoints of the spectral bands and show that these bands collapse asymptotically at the points of the spectrum of the Dirichlet problem in a rectangle obtained by gluing the lateral sides of the periodicity cell. These formulas show that the spectrum has spectral bands of length
It should be emphasized that waveguides with periodically perturbed boundaries have been the subject of research in the last decade: let us mention e.g. [34], [21], [22], [2] and [3] and the references therein. However the type of singular perturbation that we study in our paper has never been addressed. We consider a waveguide perforated by a periodic perforation string, which implies using a combination of homogenization methods and spectral perturbation theory.
As usual in waveguide theory, we first apply the Gelfand transform (cf. [6], [30], [33], [26], [11] and (11)) to convert the original problem, cf. (7), into a family of spectral problems depending on the Floquet-parameter
The above mentioned homogenization spectral problems have different boundary conditions from those considered in the literature (cf. [5], [14] and [16] for an extensive bibliography). Obtaining convergence for their spectra, correcting terms and precise bounds for discrepancies (cf. (10)), as
Let
Π={x=(x1,x2):x1∈R,x2∈(0,H)} | (1) |
be a strip of width
¯ω=ω∪∂ω⊂ϖ0, | (2) |
where
ϖ0=(−1/2,1/2)×(0,H)⊂Π. | (3) |
We also introduce the strip
ωε(j,k)={x:ε−1(x1−j,x2−εkH)∈ω}with j∈Z,k∈{0,…,N−1}, | (4) |
where
Πε=Π∖⋃j∈ZN−1⋃k=0¯ωε(j,k) | (5) |
is made equal to 1 by rescaling, and similarly, the period is made equal to
ϖε=ϖ0∖N−1⋃k=0¯ωε(0,k), |
(see b) in Figure 1). For brevity, we shall denote by
ωε=⋃j∈ZN−1⋃k=0ωε(j,k), | (6) |
while
In the domain (5) we consider the Dirichlet spectral problem
{−Δuε(x)=λεuε(x),x∈Πε,uε(x)=0,x∈∂Πε. | (7) |
The variational formulation of problem (7) refers to the integral identity
(∇uε,∇v)Πε=λε(uε,v)Πε∀v∈H10(Πε), | (8) |
where
Problem (7) gets a positive cutoff value
σε=⋃n∈NBεn, | (9) |
where
In Section 2 we address the setting of the Floquet parametric family of problems (13)-(16), obtained by applying the Gelfand transform (11) to the original problem (7). They are homogenization spectral problems in a perforated domain, the periodicity cell
Λεi(η)→Λ0i as ε→0,∀η∈[−π,π],i=1,2,⋯. |
However, this result does not give information on the spectral gaps.
Using the method of matched asymptotic expansions for the eigenfunctions of the homogenization problems (cf. Section 4) we are led to the unit cell boundary value problem (31)-(33), the so-called local problem, that is, a problem to describe the boundary layer phenomenon. Section 3 is devoted to the study of this stationary problem for the Laplace operator, which is independent of
|Λεi(η)−Λ0i−εΛ1i(η)|≤ciε3/2, | (10) |
with some
As a consequence, we deduce that the bands
[Λ0i+εBi−−ciε3/2,Λ0i+εBi++ciε3/2], |
of length
Dealing with the precise length of the band, we note that the results rely on the fact that the elements of the antidiagonal of the polarization matrix do not vanish (cf. (70)-(75)), but this is a generic property for many geometries of the unit hole
Summarizing, Section 2 addresses some asymptotics for the spectrum of the Floquet-parameter family of spectral problems; Section 3 considers the unit cell problem; Section 4 deals with the asymptotic expansions; in Section 5.1, we formulate the main asymptotic results of the paper, while the proofs are performed in Section 5.2.
In this section, we deal with the setting of the Floquet-parameter dependent spectral problems and the limit behavior of their spectra, cf. Sections 2.1 and 2.2, respectively.
The Floquet-Bloch-Gelfand transform (FBG-transform, in short)
uε(x)→Uε(x;η)=1√2π∑n∈Ze−inηuε(x1+n,x2), | (11) |
see [6] and, e.g., [30], [33], [11], [26] and [4], converts problem (7) into a
ϖε={x∈Πε:|x1|<1/2} | (12) |
see Figure 1, b. Note that
−ΔUε(x;η)=Λε(η)Uε(x;η),x∈ϖε, | (13) |
Uε(x;η)=0,x∈Γε, | (14) |
Uε(1/2,x2;η)=eiηUε(−1/2,x2;η),x2∈(0,H), | (15) |
∂Uε∂x1(12,x2;η)=eiη∂Uε∂x1(−12,x2;η),x2∈(0,H), | (16) |
where
The variational formulation of the spectral problem (13)-(16) reads:
(∇Uε,∇V)ϖε=Λε(Uε,V)ϖεV∈H1,ηper(ϖε;Γε), | (17) |
where
0<Λε1(η)≤Λε2(η)≤⋯≤Λεm(η)≤⋯→∞, | (18) |
which are repeated according to their multiplicities (see Ch. 10 in [1] and Ch. 13 in [30]). The eigenfunctions are assumed to form an orthonormal basis in
The function
η∈[−π,π]↦Λεm(η) | (19) |
is continuous and
Bεm={Λεm(η):η∈[−π,π]} | (20) |
are closed, connected and bounded intervals of the real positive axis
A first approach to the asymptotics for eigenpairs of (13)-(16) is given by the following convergence result, that we show adapting standard techniques in homogenization and spectral perturbation theory: see, e.g., Ch. 3 in [27] for a general framework and [14] for its application to spectral problems in perforated domains with different boundary conditions. Let us recall
ωε(0,0),…,ωε(0,N−1)⊂ϖ0. | (21) |
Theorem 2.1. Let the spectral problem (13)-(16) and the sequence of eigenvalues (18). Then, for any
Λεm(η)→Λ0m,as ε→0, | (22) |
where
0<Λ01<Λ02≤⋯≤Λ0m≤⋯→∞,as m→∞, | (23) |
are the eigenvalues, repeated according to their multiplicities, of the Dirichlet problem
−ΔU0(x)=Λ0U0(x),x∈υ,υ≡(0,1)×(0,H)U0(x)=0,x∈∂υ. | (24) |
Proof. First, for each fixed
0<C≤Λεm(η)≤Cm∀η∈[−π,π]. | (25) |
To obtain the lower bound in (25), it suffices to consider (17) for the eigenpair
Λεm(η)=minEεm⊂H1,ηper(ϖε;Γε)maxV∈Eεm,V≠0(∇V,∇V)ϖε(V,V)ϖε, |
where the minimum is computed over the set of subspaces
Hence, for each
Λεm(η)→Λ0m(η),Uεm(⋅;η)⇀U0m(⋅;η) in H1(ϖ0)−weak, as ε→0, | (26) |
for a certain positive
‖U;L2(ϖ0∖¯ω)‖≤C‖∇U;L2(ϖ0∖¯ω)‖∀U∈H1(ϖ0∖¯ω),U=0 on ∂ω, |
and we deduce
ε−1‖Uεm(⋅;η);L2({|x1|≤ε/2}∩ϖ0)‖2≤Cε‖∇Uεm(⋅;η);L2({|x1|≤ε/2}∩ϖ0)‖2. |
Now, taking limits as
−ΔU0m(x;η)=Λ0m(η)U0m(x;η),x1∈{(−1/2,0)∪(0,1/2)},x2∈(0,H),U0m(x;η)=0 for x2∈{0,H},x1∈(−1/2,1/2) and x1=0,x2∈(0,H),U0m(1/2,x2;η)=eiηU0m(−1/2,x2;η),x2∈(0,H),∂U0m∂x1(1/2,x2;η)=eiη∂U0m∂x1(−1/2,x2;η),x2∈(0,H), | (27) |
where the differential equation has been obtained by taking limits in the variational formulation (17) for
Now, from the orthonormality of
In addition, extending by
u0m(x;η)={U0m(x;η),x1∈(0,1/2),eiηU0m(x1−1,x2;η),x1∈(1/2,1), | (28) |
we obtain a smooth function in the rectangle
Remark 1. Note that the eigenpairs of (24) can be computed explicitly
Λ0np=π2(n2+p2H2),U0np(x)=2√Hsin(nπx1)sin(pπx2/H),p,n∈N. | (29) |
The eigenvalues
In this section, we study the properties of certain solutions of the boundary value problem in the unbounded strip
In order to obtain a corrector for the approach to the eigenpairs of (13)-(16) given by Theorem 2.1, we introduce the stretched coordinates
ξ=(ξ1,ξ2)=ε−1(x1,x2−εkH). | (30) |
which transforms each opening of the string
−ΔξW(ξ)=0,ξ∈Ξ, | (31) |
with the periodicity conditions
W(ξ1,H)=W(ξ1,0),∂W∂ξ2(ξ1,H)=∂W∂ξ2(ξ1,0),ξ1∈R, | (32) |
and the Dirichlet condition on the boundary of the hole
W(ξ)=0,ξ∈∂ω. | (33) |
Regarding (31)-(33), it should be noted that, for any
Δx+Λε=ε−2(Δξ+ε2Λε), |
and
w(x2)W(ε−1x), | (34) |
for the boundary layer. Here,
It is worth recalling that, according to the general theory of elliptic problems in domains with cylindrical outlets to infinity, cf., e.g., Ch. 5 in [26], problem (31)-(33) has just two solutions with a linear polynomial growth as
¯ω⊂(−R,R)×(0,H) | (35) |
and define the cut-off functions
χ±(y)={1, for ±y>2R,0, for ±y<R, | (36) |
where the subindex
Proposition 3.1. There are two normalized solutions of (31)-(33) in the form
W±(ξ)=±χ±(ξ1)ξ1+∑τ=±χτ(ξ1)pτ±+˜W±(ξ),ξ∈Ξ, | (37) |
where the remainder
p(Ξ)=(p++(Ξ)p+−(Ξ)p−+(Ξ)p–(Ξ)). | (38) |
Proof. The existence of two linearly independent normalized solutions
Let us consider the functions
ˆW±(ξ)=W±(ξ)∓χ±(ξ1)ξ1, | (39) |
which, obviously, satisfy (32), (33) and
−ΔξˆW±(ξ)=F±(ξ),ξ∈Ξ, | (40) |
with
Let
‖W,H‖=‖∇yW;L2(Ξ)‖. |
The variational formulation of (40), (32) and (33) reads: to find
(∇yˆW±,∇yV)Ξ=(F±,V)Ξ∀V∈H. | (41) |
Since
In addition, since for each
ˆWτ(ξ)=cτ±+O(e−(±ξ1)2π/H) as ±ξ1→+∞, |
where the constants
cτ±=limT→∞1H∫H0ˆWτ(±T,ξ2)dξ2=limT→∞1H∫H0(Wτ(±T,ξ2)−τδτ,±T)dξ2. | (42) |
Obviously,
In this section, we detect certain properties of the matrix
Proposition 3.2. The matrix
Proof. We represent (37) in the form
W±(ξ)=W±0(ξ)+{±ξ1−R,±ξ1>R,0,±ξ1<R. | (43) |
The function
[W±0]±(ξ2)=0,[∂W±0∂|ξ1|]±(ξ2)=−1,ξ2∈(0,H), |
where
In what follows, we write the equations for
∫H0Wτ0(±R,ξ2)dξ2=−∫H0Wτ0(±R,ξ2)[∂W±0∂|ξ1|]±(ξ2)dξ2=−(∇ξWτ0,∇ξW±0)Ξ. | (44) |
On the other hand, on account of (43) and the definition of
Wτ0(±R,ξ2)=Wτ(±R,ξ2) and [∂Wτ∂|ξ1|]±(ξ2)=0. |
Consequently, we can write
∫H0Wτ0(±R,ξ2)dξ2=−∫H0Wτ(±R,ξ2)[∂W±0∂|ξ1|]±(ξ2)dξ2=∫H0(Wτ(±R,ξ2)[∂W±0∂|ξ1|]±(ξ2)−W±0(±R,ξ2)[∂Wτ∂|ξ1|]±(ξ2))dξ2, |
and using again the Green formula for
∫H0Wτ0(±R,ξ2)dξ2=+limT→∞∫H0(Wτ(τT,ξ2)∂W±0∂|ξ1|(τT,ξ2)−W±0(τT,ξ2)∂Wτ∂|ξ1|(τT,ξ2))dξ2=−H(pτ±(Ξ)+δτ,±R). | (45) |
Here, we have used the following facts:
W±0(ξ)=χ±(ξ1)(p±±+R)+χ∓(ξ1)p∓±+˜W±(ξ). |
Considering (44) and (45) we have shown the equality for the Gram matrix
(∇ξWτ0,∇ξW±0)Ξ=H(pτ±(Ξ)+δτ,±R), |
which gives the symmetry and the positiveness of the matrix
Let us note that our results above apply for Lipschitz domains or even cracks as it was pointed out in Section 2.1. Now, we get the following results in Propositions 3.3 and 3.4 depending on whether
Proposition 3.3. Let
H(2p+−−p++−p–)>mes2(ω). |
Proof. We consider the linear combination
W0(ξ)=W+(ξ)−W−(ξ)−ξ1=χ+(ξ1)(p++−p+−)−χ−(ξ1)(p–−p−+)+˜W0(ξ). |
It satisfies
−ΔξW0(ξ)=0,ξ∈Ξ,W0(ξ)=−ξ1,ξ∈∂ω, |
with the periodicity conditions in the strip, and
0<‖∇W0;L2(Ξ)‖2+mes2(ω)=−∫∂ωξ1∂ν(ξ1)dν+∫∂ωW0∂ν(W0(ξ))dν=−∫∂ωξ1∂ν(ξ1+W0(ξ))dν=∫∂ω(∂νξ1(ξ1+W0(ξ))−ξ1∂ν(ξ1+W0(ξ)))dν=−limT→∞∑±±∫H0W0(±T,ξ2)dξ2=−H(p+++p–−p+−−p−+). |
Remark 2. observe that for a hole
p++=p–. | (46) |
Indeed, this is due to the fact that each one of the two normalized solutions in (37) are related with each other by symmetry. Also, we note that, on account of Proposition 3.2, the symmetry
Proposition 3.4. Let
p+−=p−+>0. | (47) |
In addition,
Proof. First, let us note that due to the symmetry
W−(ξ1,ξ2)={−ξ1+W∗(−ξ1,ξ2),ξ1<0,W∗(ξ1,ξ2),ξ1>0. | (48) |
where
−ΔξW∗(ξ)=0, for ξ∈Π+,W∗(0,ξ2)=0, for ξ2∈(h,H−h),−∂ξ1W∗(0,ξ2)=1/2, for ξ2∈(0,h)∪(H−h,H). | (49) |
Indeed, denoting by
[˜W∗](0,ξ2)=0,[∂˜W∗∂ξ1](0,ξ2)=−1, |
and hence, the function on the right hand side of (48) is a harmonic function in
Now, considering (49), integrating by parts on
∫Υ(0)W∗(0,ξ2)dξ2=limT→∞H∫0W∗(T,ξ2)dξ2=Hp−+(Ξ). |
Similarly, from (49), we get
0=−∫Π+W∗(ξ)ΔξW∗(ξ)dξ=∫Π+|∇ξW∗(ξ)|2dξ−12∫Υ(0)W∗(0,ξ2)dξ2. |
Therefore, we deduce
H2p−+(Ξ)=∫Π+|∇ξW∗(ξ)|2dξ>0 | (50) |
and from the symmetry of
Also, from the definition (48), we have
From Proposition 3.4, note that when
¯ω={ξ:δ−2ξ21+(ξ2−H/2)2≤τ2},τ=H/2−h, | (51) |
(47) holds true, for a small
In this section we construct asymptotic expansions for the eigenpairs (
Let
Λεm=Λ0m+εΛ1m(η)+⋯. | (52) |
To construct asymptotics of the corresponding eigenfunctions
Uεm(x;η)=U0m(x;η)+εU1m(x;η)+⋯ | (53) |
as the outer expansion, and
Uεm(x;η)=ε∑±wm±(x2;η)W±(xε)+⋯ | (54) |
as the inner expansion near the perforation string, cf. (4) and (21).
Above,
U0m(x;η)={U0m(x),x1∈(0,1/2),e−iηU0m(x1+1,x2),x1∈(−1/2,0), | (55) |
First, let us notice that
Uεm(x;η)=0+x1∂U0m∂x1(0,x2)+εU1m(+0,x2;η)+⋯,x1>0,Uεm(x;η)=0+x1e−iη∂U0m∂x1(1,x2)+εU1m(−0,x2;η)+⋯,x1<0, | (56) |
where, for second formula (56), we have used (55).
The inner expansion (54) is processed by means of decompositions (37). We have
Uεm(x;η)=εwm+(x2;η)(ξ1+p++)+εwm−(x2;η)p−++⋯,ξ1>0,Uεm(x;η)=εwm−(x2;η)(−ξ1+p–)+εwm+(x2;η)p+−+⋯,ξ1<0. | (57) |
Recalling relationship between
wm+(x2;η)=∂U0m∂x1(0,x2),wm−(x2;η)=−e−iη∂U0m∂x1(1,x2), | (58) |
and also obtain the equalities
U1m(+0,x2;η)=∑τ=±wmτ(x2;η)pτ+,U1m(−0,x2;η)=∑τ=±wmτ(x2;η)pτ−. | (59) |
Formulas (58) define coefficients of the linear combination (54) while formulas (59) are the boundary conditions for the correction term in (53). Moreover, inserting ans
{−ΔxU1m(x;η)−Λ0mU1m(x;η)=Λ1m(η)U0m(x;η),x∈ϖ0,x1≠0,U1m(x1,H;η)=U1m(x1,0;η)=0,x1∈(−1/2,0)∪(0,1/2), | (60) |
and the quasi-periodic conditions with
Since
∫ϖ0Λ1m(η)U0m(x;η)¯U0m(x;η)dx=H∫0U1m(−0,x2;η)¯∂U0m∂x1(−0,x2;η)dx2−H∫0U1m(+0,x2;η)¯∂U0m∂x1(+0,x2;η)dx2. |
Thus, by (55) and (59), the only compatibility condition in (60) (recall that
Λ1m(η)=−H∫0¯Bm(x2;η)⋅p(Ξ)Bm(x2;η)dx2 | (61) |
where
Bm(x2;η)=(∂U0m∂x1(0,x2),−e−iη∂U0m∂x1(1,x2))T∈C2, | (62) |
and it determines uniquely the second term of the ansatz (52). Here and in what follows, the top index
Also, from (53), (54) and (57) the composite expansion approaching
Uεm(x;η)≈U0m(x;η)+εU1m(x;η)+ε∑τ=±wmτ(x2;η)Wτ(xε)−(εwm±(x2;η)(ε−1|x1|+p±±)+εwm∓(x2;η)p∓±),±x1≥0. | (63) |
We address the case where
Λεm+l(η)→Λ0m+l as ε→0, for l=0,⋯,κm−1. | (64) |
Let
Following Section 4.1, for each
Λεm+l=Λ0m+εΛ1m+l(η)+⋯, | (65) |
the outer expansion for
Uεm+l(x;η)=U0m+l(x;η)+εU1m+l(x;η)+⋯, | (66) |
and the inner expansion
Uεm(x;η)=ε∑±wm+l±(x2;η)W±(xε)+⋯, | (67) |
where the terms
By repeating the reasoning in Section 4.2, we obtain formulas for the above mentioned terms in (65), (66) and (67) by replacing index
−ΔxU1m+l(x;η)−Λ0mU1m+l(x;η)=Λ1m+l(η)U0m+l(x;η),x∈ϖ0,x1≠0, |
and integrating by parts, we obtain
∫ϖ0Λ1m+l(η)U0m+l(x;η)¯U0m+l′(x;η)dx=−H∫0(∂U0m+l′∂x1(0,x2),−eiη∂U0m+l′∂x1(1,x2))⋅p(Ξ)×(∂U0m+l∂x1(0,x2),−e−iη∂U0m+l∂x1(1,x2))Tdx2. |
Since the eigenfunctions
H∫0∂U0m+l′∂x1(x∗1,x2)∂U0m+l∂x1(x∗1,x2)dx2=0, with x∗1∈{0,1},l≠l′, |
and, hence, for each
Λ1m+l(η)=−H∫0¯Bm+l(x2;η)⋅p(Ξ)Bm+l(x2;η)dx2, | (68) |
where
Bm+l(x2;η)=(∂U0m+l∂x1(0,x2),−e−iη∂U0m+l∂x1(1,x2))T. | (69) |
Therefore we have determined completely all the terms in the asymptotic ans
In this section, we justify the results obtained by means of matched asymptotic expasions in Section 4. Since the case in which all the eigenvalues of the Dirichlet problem (24) are simple can be a generic property, we first consider this case, cf. Theorem 5.1 and Corollary 5.1, and then the case in which these eigenvalues have a multiplicity greater than
Theorem 5.1. Let
|Λεm(η)−Λ0m−εΛ1m(η)|≤cmε3/2 | (70) |
and there are no other different eigenvalues in the sequence (18) satisfying (70).
Theorem 5.1 shows that
In order to detect the gaps between consecutive spectral bands (20) it is worthy writing formulas
Λ1m(η)=B0(m)+B1(m)cos(η), with B0(m)=H∫0(p++|∂U0m∂x1(0,x2)|2+p–|∂U0m∂x1(1,x2)|2)dx2,B1(m)=2p+−H∫0∂U0m∂x1(0,x2)∂U0m∂x1(1,x2)dx2, | (71) |
which are obtained from (61) and (62). Formula (29) demonstrates that
B0(m)=(p+++p–)H∫0|∂U0m∂x1(0,x2)|2dx2, |
and that the integral in
Remark 3. Let us consider that the eigenvalue
B0(m)=2(p+++p–)n2π2,B1(m)=(−1)n4p+−n2π2, |
and, consequently,
Λ1m(η)=2(p+++p–)n2π2+(−1)n4p+−n2π2cos(η). | (72) |
Corollary 5.1. Under the hypothesis of Theorem 5.1, the endpoints
|Bε±(m)−Λ0m−ε(B0(m)±|B1(m)|)|≤cmε3/2. | (73) |
Hence, the length of the band
Note that for the holes such that the polarization matrix (38) satisfies
Theorem 5.2. Let
|Λεm+l0(η)−Λ0m−εΛ1m+l(η)|≤cmε3/2. | (74) |
In addition, when
Corollary 5.2. Under the hypothesis in Theorem 5.2, the spectral bands
[Λ0m+εmin0≤l≤κm−1η∈[−π,π]Λ1m+l(η)−cmε3/2,Λ0m+εmax0≤l≤κm−1η∈[−π,π]Λ1m+l(η)+cmε3/2]. | (75) |
Hence, the length of the the bands
Remark 4. Under the hypothesis of Theorem 5.2, it may happen that, for
Remark 5. Notice that the positive cutoff value
In this section we prove the results of Theorems 5.1 and 5.2 and of their respective corollaries.
Proof of Theorem 5.1. Let us fix
⟨Tε(η)Uε,Vε⟩=(Uε,Vε)ϖε∀Uε,Vε∈H1,ηper(ϖε;Γε). | (76) |
The integral identity (17) for problem (13)-(16) can be rewritten as the abstract equation
Tε(η)Uε(⋅;η)=τε(η)Uε(⋅;η)in H1,ηper(ϖε;Γε), |
with the new spectral parameter
τε(η)=(1+Λε(η))−1. | (77) |
Since
{τεm(η)=(1+Λεm(η))−1}m∈N. |
For the point
tεm(η)=(1+Λ0m+εΛ1m(η))−1, | (78) |
cf. (52) and (61), we construct a function
‖Uεm;H1,ηper(ϖε;Γε)‖≥cm, | (79) |
‖Tε(η)Uεm−tεm(η)Uεm;H1,ηper(ϖε;Γε)‖≤Cmε3/2, | (80) |
where
‖(Tε(η)−tεm(η))−1;H1,ηper(ϖε;Γε)→H1,ηper(ϖε;Γε)‖≥c−1mε−3/2, |
with
dist(tεm(η),σ(Tε(η))=‖(Tε(η)−tεm(η))−1;H1,ηper(ϖε;Γε)→H1,ηper(ϖε;Γε)‖−1 |
supported by the spectral decomposition of the resolvent (cf., e.g., Section V.5 in [9] and Ch. 6 in [1]), we deduce that the closed segment
[tεm(η)−cmε3/2,tεm(η)+cmε3/2] |
contains at least one eigenvalue
|(1+Λεp(η))−1−(1+Λ0m+εΛ1m(η))−1|≤cmε3/2. | (81) |
Then, simple algebraic calculations (cf. (81) and (25)) show that, for a
|Λεp(η)−Λ0m−εΛ1m(η)|≤Cmε3/2 | (82) |
is satisfied with a constant
To conclude with the proof of Theorem 5.1, there remains to present a function
Vεmout(x;η)=U0m(x;η)+εU1m(x;η), | (83) |
where
Vεmin(x;η)=ε∑±wm±(x2;η)W±(ε−1x), | (84) |
and
Vεmmat(x;η)=εwm±(x2;η)(ε−1|x1|+p±±)+εwm∓(x2;η)p∓±,±x1>0, | (85) |
with
Uεm(x;η)=Xε(x1)Vεmout(x;η)+X(x1)Vεmin(x;η)−Xε(x1)X(x1)Vεmmat(x;η), | (86) |
where
Xε(x1)={1, for |x1|>2Rε,0, for |x1|<Rε, and X(x1)={1, for |x1|<1/6,0, for |x1|>1/3. | (87) |
Note that (85) takes into account components in both expressions (83) and (84), but the last subtrahend in
First, let us show that
First of all, we recall (83) and (87) to derive
‖Uεm;H1,ηper(ϖε;Γε)‖≥‖Uεm;L2((1/3,1/2)×(0,H))‖=‖Vεmout;L2((1/3,1/2)×(0,H))‖≥‖U0m;L2((1/3,1/2)×(0,H))‖−ε‖U1m;L2((1/3,1/2)×(0,H))‖≥c>0, |
for a small
Using (76) and (78), we have
‖Tε(η)Uεm−tεm(η)Uεm;H1,ηper(ϖε;Γε)‖=sup|⟨Tε(η)Uεm−tεm(η)Uεm,Wε⟩|=(1+Λ0m+εΛ1m(η))−1sup|(∇Uεm,∇Wε)ϖε−(Λ0m+εΛ1m(η))(Uεm,Wε)ϖε|, | (88) |
where the supremum is computed over all
‖Wε;H1,ηper(ϖε;Γε)‖≤1. |
Taking into account the Dirichlet conditions on
∫ΠT∖¯ω|U|2dy≤CT∫ΠT∖¯ω|∇yU|2dy∀U∈H1(ΠT∖¯ω),U=0 on ∂ω, |
where
∫∞01t2z(t)2dt≤4∫∞0|dzdt(t)|2dt∀z∈C1[0,∞),z(0)=0. |
Then, we have
‖(ε+|x1|)−1Wε;L2(ϖε)‖≤c‖∇Wε;L2(ϖε)‖≤c. | (89) |
Clearly, from (71),
|(∇Uεm,∇Wε)ϖε−(Λ0m+εΛ1m(η))(Uεm,Wε)ϖε|=|(ΔUεm+(Λ0m+εΛ1m(η))Uεm,Wε)ϖε|. |
On the basis of (83)-(86) we write
ΔUεm+(Λ0m+εΛ1m(η))Uεm=Xε(ΔU0m+Λ0mU0m+ε(ΔU1m+Λ0mU1m+Λ1mU0m)+ε2Λ1mU1m)+[Δ,Xε](Vεmout−Vεmmat)+X(ΔVεmin−XεΔVεmmat)+[Δ,X](Vεmin−Vεmmat)+(Λ0m+εΛ1m)X(Vεmin−XεVεmmat)=:Sε1+Sε2+Sε3+Sε4+Sε5. | (90) |
Here,
Considering
|(Sε1,Wε)ϖε|≤ε2Λ1m(η)‖U1m;L2(ϖε)‖‖Wε;L2(ϖε)‖≤Cmε2. |
As regards
|Vεmout(x;η)−Vεmmat(x;η)|≤c(|x1|2+ε|x1|),|∂Vεmout∂x1(x;η)−∂Vεmmat∂x1(x;η)|≤c(|x1|+ε),±x1∈[εR,2εR]. |
Above, we have also used the smoothness of the function
|(Sε2,Wε)ϖε|≤‖Sε2;L2(ϖεεR)‖‖Wε;L2(ϖεεR)‖≤cε‖(ε+|x1|)−1Wε;L2(ϖε)‖×(H∫02εR∫εR(1ε2|Vεmout∂x1−Vεmmat∂x1|2+1ε4|Vεmout−Vεmmat|2)d|x1|dx2)12≤c(1ε2ε2+1ε4ε4)12(mes2ϖεεR)12ε‖(ε+|x1|)−1Wε;L2(ϖε)‖≤cε32. |
Dealing with
ΔVεmin(x;η)−Xε(x1)ΔVεmmat(x;η)=2∑±∂wm±∂x2(x2;η)∂W±∂ξ2(y)+ε∑±∂2wm±∂x22(x2;η)˜W±(y), |
when
|(Sε3,Wε)ϖε|≤c(‖(ε+|x1|)∂W±∂ξ2;L2(ϖε)‖+ε‖(ε+|x1|)˜W±;L2(ϖε)‖)‖1ε+|x1|Wε;L2(ϖε)‖≤c(1/2∫0(ε+t)2e−2δt/εdt)12‖∇Wε;L2(ϖε)‖≤cε32. |
Above, obviously, we take the positive constant
|(Sε5,Wε)ϖε|≤cε32. |
Moreover, the supports of the coefficients
|(Sε4,Wε)ϖε|≤ce−2δ/(3ε). |
Revisiting the obtained estimates we find the worst bound
The fact that the constants
−(∂∂y1+iη)(∂∂y1+iη)−∂2∂y22, | (91) |
and therefore, performing this change in (60), gives the solution
Proof of Corollary 5.1. Due to the continuity of the function (19), the maximum and minimum of
In order to show (73) for the maximum
Λ0m+εB0(m)+ε|B1(m)|−cmε3/2≤Λεm(η+)≤Λ0m+εB0(m)+ε|B1(m)|+cmε3/2 |
and
Λ0m+εΛ1m(η+ε,m)−cmε3/2≤Λεm(η+ε,m)≤Λ0m+εΛ1m(η+ε,m)+cmε3/2. |
Consequently, from (71), we derive
Λ0m+εB0(m)+ε|B1(m)|−cmε3/2≤Λεm(η+)≤Λεm(η+ε,m)≤Λ0m+εB0(m)+ε|B1(m)|+cmε3/2, |
which gives (73) for
We proceed in a similar way for the minimum
[Λ0m+εB0(m)−ε|B1(m)|−cmε3/2,Λ0m+εB0(m)+ε|B1(m)|+cmε3/2] |
Therefore, the whole band
Proof of Theorem 5.2. This proof holds exactly the same scheme of Theorem 5.1. Indeed, for each
|Λεp(η)−Λ0m−εΛ1m+l(η)|≤Cm,lε3/2 | (92) |
is satisfied for a certain natural
We use a classical argument of contradiction (cf. [15] and [25]). We consider the set of functions
‖Uεm+l;H1,ηper(ϖε;Γε)‖≥˜cm and |⟨Uεm+l,Uεm+l′⟩|≤˜Cmε1/2, with l≠l′, | (93) |
for certain constants
Then, we define
|(1+Λεp(l)(η))−1−(1+Λ0m+εΛ1m+l(η))−1|≤˜cmε3/2, | (94) |
for a constant
‖˜Wεm+l−˜Uεm+l;H1,ηper(ϖε;Γε)‖≤˜Cm, | (95) |
where
‖˜Uεm+l−Wεm+l;H1,ηper(ϖε;Γε)‖≤˜c−1mmax0≤l≤κm−1Cl,m, |
and some straightforward computation (cf., eg., Lemma 1 in Ch. 3 of [27]). Now, from (93) and (95) and straightforward computations we obtain
|⟨˜Wεm+l,˜Wεm+l′⟩|≤5˜Cm with l≠l′, | (96) |
and this allows us to assert that set
κm−1∑l=0αεl˜Wεm+l=0. |
Let us consider
⟨˜Wεm,˜Wεm⟩≤κm−1∑l=1|αεlαε0||⟨˜Wεm+l,˜Wεm⟩|≤(κm−1)5˜Cm. |
Now, setting
Thus,
[1] |
T. Aiki, K. Kumazaki, A. Muntean, A free boundary problem describing migration into rubbers-quest of the large time behavior, Z. Angew. Math. Mech., 102 (2022), e202100134. https://doi.org/10.1002/zamm.202100134 doi: 10.1002/zamm.202100134
![]() |
[2] | E. Brunier, G. Antonini, Experimental and numerical description of the diffuision of a liquid in a swelling elastomer, In: C. A. Brebbia, G. A. Karamidas, Eds., Computational Methods and Experimental Measurements, Berlin: Springer, 1984,623–632. |
[3] |
G. Chagnon, E. Verron, L. Gornet, G. Marckmann, P. Charrier, On the relevance of Continuum Damage Mechanics as applied to the Mullins effect in elastomers, J. Mech. phys. Solids, 52 (2004), 1627–1650. https://doi.org/10.1016/j.jmps.2003.12.006 doi: 10.1016/j.jmps.2003.12.006
![]() |
[4] | N. Kenmochi, Solvability of nonlinear evolution equations with time-dependent constraints and applications, Bull. Fac. Education, Chiba Univ., 30 (1981), 1–87. |
[5] |
K. Kumazaki, A. Muntean, Local weak solvability of a moving boundary problem describing swelling along a halfline, Netw. Heterog. Media, 14 (2019), 445–496. https://doi/10.3934/nhm.2019018 doi: 10.3934/nhm.2019018
![]() |
[6] |
K. Kumazaki, A. Muntean, Global weak solvability, continuous dependence on data, and large time growth of swelling moving interfaces, Interfaces Free Bound., 22 (2020), 27–49. https://doi.org/10.4171/ifb/431 doi: 10.4171/ifb/431
![]() |
[7] | S. Nepal, R. Meyer, N. H. Kröger, T. Aiki, A. Muntean, Y. Wondmagegne, U. Giese, A moving boundary approach of capturing diffusants penetration into rubber: FEM approximation and comparison with laboratory measurements, Kautsch. Gummi, Kunsts., 5 (2020), 61–69. |
[8] |
Z. Ren, A. S. Verma, Y. Li, J. J.E. Teuwen, Z. Jiang, Offshore wind turbine operations and maintenance: A state-of-the-art review, Renew. Sust. Energ. Rev., 144 (2021), 110886. https://doi.org/10.1016/j.rser.2021.110886 doi: 10.1016/j.rser.2021.110886
![]() |
[9] | A. Visintin, Introduction to the models of phase transitions, Bollettino dell'Unione Matematica Italiana, 1 (1998), 1–47. |
1. | Delfina Gómez, Sergei A. Nazarov, Rafael Orive-Illera, María-Eugenia Pérez-Martínez, Spectral gaps in a double-periodic perforated Neumann waveguide, 2023, 131, 18758576, 385, 10.3233/ASY-221776 | |
2. | D. Gómez, S. A. Nazarov, R. Orive-Illera, M.-E. Pérez-Martínez, Remark on Justification of Asymptotics of Spectra of Cylindrical Waveguides with Periodic Singular Perturbations of Boundary and Coefficients, 2021, 257, 1072-3374, 597, 10.1007/s10958-021-05506-z | |
3. | Sergei A. Nazarov, Jari Taskinen, Band-gap structure of the spectrum of the water-wave problem in a shallow canal with a periodic family of deep pools, 2023, 36, 1139-1138, 263, 10.1007/s13163-021-00420-z | |
4. | D. Gómez, S. A. Nazarov, R. Orive-Illera, M. -E. Pérez-Martínez, 2022, Chapter 7, 978-3-031-07170-6, 95, 10.1007/978-3-031-07171-3_7 | |
5. | Delfina Gómez, Sergei A. Nazarov, Rafael Orive‐Illera, María‐Eugenia Pérez‐Martínez, Asymptotic stability of the spectrum of a parametric family of homogenization problems associated with a perforated waveguide, 2023, 0025-584X, 10.1002/mana.202100589 | |
6. | D. Gómez, S. A. Nazarov, M.-E. Pérez-Martínez, Pointwise Fixation along the Edge of a Kirchhoff Plate, 2023, 1072-3374, 10.1007/s10958-023-06862-8 |