BAIL 2006 Book of Abstracts - Institut für Numerische und ...

BAIL 2006 Book of Abstracts - Institut für Numerische und ... BAIL 2006 Book of Abstracts - Institut für Numerische und ...

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M. HAMOUDA, R. TEMAM: Boundary layers for the Navier-Stokes equations : asymptotic analysis ✬ ✫ Boundary layers for the Navier-Stokes equations : asymptotic analysis. M. Hamouda ♯ and R. Temam ∗♯ ∗ Laboratoire d’Analyse Numérique, Université de Paris–Sud, Orsay, France. ♯ The Institute for Scientific Computing and Applied Mathematics, Indiana University, Bloomington, IN, USA. Abstract In this talk, we consider the asymptotic analysis of the solutions of the Navier- Stokes problem, when the viscosity goes to zero; we consider the flow in a channel of R 3 , in the non-characteristic boundary case. More precisely, a complete asymptotic expansion, at all orders, is given in the linear case. For the full nonlinear Navier-Stokes solution, we give a convergence theorem up to order 1, thus improving and simplifying the results of [TW]. MSC : 76D05, 76D10, 35C20. We consider the Navier-Stokes equations in a channel Ω∞ = R 2 × (0, h) with a permeable boundary, making the boundaries z = 0, h, non-characteristic. More precisely we have ⎧ ⎪⎨ ⎪⎩ which is equivalent to ⎧ ⎪⎨ ⎪⎩ ∂u ε ∂t − ε∆uε + (u ε .∇) u ε + ∇p ε = f, in Ω∞, div u ε = 0, in Ω∞, u ε = (0, 0, −U), on Γ∞, u ε is periodic in the x and y directions with periods L1, L2, u ε | t=0 = u0, ∂v ε ∂t − ε∆vε − UD3v ε + (v ε .∇) v ε + ∇p ε = f, in Ω∞, div v ε = 0, in Ω∞, v ε = 0, on Γ∞, v ε is periodic in the x and y directions with periods L1, L2, v ε | t=0 = v0. Here Γ∞ = ∂Ω∞ = R 2 × {0, h} and we introduce also Ω and Γ : Ω = (0, L1) × (0, L2) × (0, h), Γ = (0, L1) × (0, L2) × {0, h}. Speaker: HAMOUDA, M. 88 BAIL 2006 1 (0.1) (0.2) ✩ ✪

M. HAMOUDA, R. TEMAM: Boundary layers for the Navier-Stokes equations : asymptotic analysis ✬ ✫ We assume that f and u0 are given functions as regular as necessary in the channel Ω∞, and that U is a given constant; at the price of long technicalities, we can also consider the case where U is nonconstant everywhere. Theorem 0.1 For each N ≥ 1, there exists C > 0 and for all k ∈ [0, N] an explicit given function θ k,ε such that : �v ε N� − ε k (v k + θ k,ε �L∞ (0,T ;L2 (Ω)) ≤ C ε N+1 , (0.3) �v ε − k=0 N� k=0 ε k (v k + θ k,ε � L 2 (0,T ;H 1 (Ω)) ≤ C ε N+1/2 , (0.4) where L 2 (Ω) = (L 2 (Ω)) 3 , H 1 (Ω) = (H 1 (Ω)) 3 , and C denotes a constant which depends on the data (and N) but not on ε. Here v ε denotes the solution of the linearized problem of (0.2) and v k the ones of the limit problems (ε = 0) at all orders. The second result concerns the solution of the full nonlinear problem (0.2) : Theorem 0.2 For v ε solution of the Navier-Stokes problem (0.2), there exist a time T∗ > 0, correctors function θ 0,ε and θ 1,ε explicitly given, and a constant κ > 0 depending on the data but not on ε, such that : �v ε − (v 0 + θ 0,ε ) − ε(v 1 + θ 1,ε )� L ∞ (0,T∗; L 2 (Ω)) ≤ κ ε 2 , (0.5) �v ε − (v 0 + θ 0,ε ) − ε(v 1 + θ 1,ε )� L 2 (0,T∗; H 1 (Ω)) ≤ κ ε 3/2 . (0.6) We recall here the limit problem which is the Euler problem and its solution v0 satisfies : ⎧ ∂v ⎪⎨ ⎪⎩ 0 ∂t − UD3v 0 + (v 0 .∇) v 0 + ∇p 0 = f, in Ω∞, div v 0 = 0, in Ω∞, v 0 3 = 0, on Γ0, v 0 = 0, on Γh, v 0 (0.7) is periodic in the x and y, directions with periods L1, L2. It is obvious that we can not expect a convergence result between v ε and v 0 (in H 1 (Ω) for example) and more precisely we are leading with a boundary layer problem close to some parts of the boundary Γ. This is the main object of our work. At the following order v 1 is solution of ⎧ ⎪⎨ ⎪⎩ ∂v 1 ∂t − UD3v 1 + (v 1 .∇) v 0 + (v 0 .∇) v 1 + ∇p 1 = − ∂ϕ0 ∂t + UD3ϕ 0 − (v 0 .∇) ϕ 0 − (ϕ 0 .∇) v 0 + ∆v 0 , in Ω∞, div v 1 = 0, in Ω∞, v 1 3 = 0, on Γ0, v 1 = 0, on Γh, v 1 is periodic in the x and y, directions with periods L1, L2. The function ϕ 0 is a known function at this level. 2 Speaker: HAMOUDA, M. 89 BAIL 2006 (0.8) ✩ ✪

M. HAMOUDA, R. TEMAM: Bo<strong>und</strong>ary layers for the Navier-Stokes equations :<br />

asymptotic analysis<br />

✬<br />

✫<br />

Bo<strong>und</strong>ary layers for the Navier-Stokes equations : asymptotic<br />

analysis.<br />

M. Hamouda ♯ and R. Temam ∗♯<br />

∗ Laboratoire d’Analyse Numérique, Université de Paris–Sud, Orsay, France.<br />

♯ The <strong>Institut</strong>e for Scientific Computing and Applied Mathematics,<br />

Indiana University, Bloomington, IN, USA.<br />

Abstract<br />

In this talk, we consider the asymptotic analysis <strong>of</strong> the solutions <strong>of</strong> the Navier-<br />

Stokes problem, when the viscosity goes to zero; we consider the flow in a channel <strong>of</strong><br />

R 3 , in the non-characteristic bo<strong>und</strong>ary case. More precisely, a complete asymptotic<br />

expansion, at all orders, is given in the linear case. For the full nonlinear Navier-Stokes<br />

solution, we give a convergence theorem up to order 1, thus improving and simplifying<br />

the results <strong>of</strong> [TW].<br />

MSC : 76D05, 76D10, 35C20.<br />

We consider the Navier-Stokes equations in a channel Ω∞ = R 2 × (0, h) with a permeable<br />

bo<strong>und</strong>ary, making the bo<strong>und</strong>aries z = 0, h, non-characteristic. More precisely we<br />

have<br />

⎧<br />

⎪⎨<br />

⎪⎩<br />

which is equivalent to<br />

⎧<br />

⎪⎨<br />

⎪⎩<br />

∂u ε<br />

∂t − ε∆uε + (u ε .∇) u ε + ∇p ε = f, in Ω∞,<br />

div u ε = 0, in Ω∞,<br />

u ε = (0, 0, −U), on Γ∞,<br />

u ε is periodic in the x and y directions with periods L1, L2,<br />

u ε | t=0 = u0,<br />

∂v ε<br />

∂t − ε∆vε − UD3v ε + (v ε .∇) v ε + ∇p ε = f, in Ω∞,<br />

div v ε = 0, in Ω∞,<br />

v ε = 0, on Γ∞,<br />

v ε is periodic in the x and y directions with periods L1, L2,<br />

v ε | t=0 = v0.<br />

Here Γ∞ = ∂Ω∞ = R 2 × {0, h} and we introduce also Ω and Γ :<br />

Ω = (0, L1) × (0, L2) × (0, h), Γ = (0, L1) × (0, L2) × {0, h}.<br />

Speaker: HAMOUDA, M. 88 <strong>BAIL</strong> <strong>2006</strong><br />

1<br />

(0.1)<br />

(0.2)<br />

✩<br />

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