Canonical pressure flux #
The pressure is paired with compact smooth tests through its canonical Riesz functional. Every integral used to split the weighted pairing is shown to be integrable before its norm is estimated.
Compact time tests of the conservative pressure identity #
The temporal test has topological support inside the open time interval. The spatial test is smooth and compactly supported. Consequently all pairings are ordinary Lebesgue integrals even when the pressure grows at spatial infinity.
A time cutoff supported in an open set turns a continuous function on that set into a globally continuous product, regardless of its values outside.
Integration by parts with a temporal test supported away from both endpoints. Only the cutoff-weighted derivative needs to be integrable.
The compact pressure-gradient identity integrated against a time test. Both derivatives of the velocity have transferred to the two test functions.
The same identity as an ordinary set integral over the closed time interval, convenient for subsequent Fubini and norm estimates.
Compact tests used in pressure recovery #
Real compact smooth tests are embedded in the actual complex Schwartz space. The differential operators commute with this embedding. The pressure identities below continue to pair the physical pressure only with compact spatial tests.
The canonical complex Schwartz test associated to a real compact test.
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- NavierStokesR3.PressureRecovery.realTest ψ hψ hcψ = NavierStokesR3.CompactSchwartz.ofCompactSupport (fun (x : NavierStokesR3.ProblemStatement.Space) => ↑(ψ x)) ⋯ ⋯
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A compact complex Schwartz test splits into two compact real tests.
Compact harmonicity of a complex linear functional can be verified using real scalar tests alone.
The differentiated pressure Poisson equation, still tested only against compact smooth functions. The derivative order agrees with the Riesz symbol.
The compact physical pressure-gradient pairing is continuous at interior times. Joint smoothness and the local equation suffice.
Weak time continuity from uniform spatial L¹ bounds #
A jointly continuous scalar field with uniformly bounded spatial L¹ norm
has continuous pairings with every continuous test vanishing at infinity.
Only the test is approximated by compactly supported functions; no support or
derivative bound is imposed on the field.
A test function vanishing at infinity is bounded.
Pairing an L¹ scalar field with a bounded continuous complex test is
integrable.
The original, untruncated pairing is a genuine Bochner integral.
The compact approximation to the spatial test.
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Cutting off the test cannot enlarge its pointwise error beyond its norm.
The compact approximations converge uniformly on all of space.
Uniform error in the test controls error in its pairing by the L¹
norm of the scalar field.
Compactly truncated pairings are continuous on an arbitrary time set.
Uniform spatial L¹ bounds upgrade compact-test continuity to continuity
for every continuous test vanishing at infinity.
Pressure recovery for smooth finite-energy comparisons #
The physical pressure is tested only against compact smooth functions. Its canonical representative is recovered from the conservative equation, time averaging, and the vanishing theorem for harmonic Sobolev-bounded functionals.
Time averages of finite-energy fields #
These averages use the ordinary Bochner integral on a finite closed time interval. Their spatial integrability follows from joint continuity and the uniform spatial integral bounds; no time derivative or global spatial derivative bound is used.
The time average against a scalar weight on the comparison interval.
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Joint continuity supplies measurability for the product of restricted time measure and ordinary spatial volume.
An integrable bound on the spatial norm integrals proves integrability on the whole slab.
Weighting by a continuous scalar preserves slab continuity.
Each time slice at a fixed spatial point is integrable, including at the endpoints of the closed time interval.
Bounded linear maps commute with these time averages pointwise.
A field with a uniform spatial L¹ bound has an integrable weighted
integrand on the time-space slab.
The time average of a uniformly L¹ field lies in spatial L¹.
The spatial L¹ norm of an average is bounded by the uniform spatial
norm bound times the time integral of the weight's absolute value.
Fubini for a uniformly L¹ field and a continuous time weight.
Cauchy--Schwarz for a Bochner integral over a finite measure space.
Integrating in the finite time variable sends a square-integrable joint field to a square-integrable spatial field.
The quantitative estimate behind square-integrability of the time integral.
Squared norm integrability of the weighted joint field follows from a uniform spatial square-integral bound.
The time average of a uniformly square-integrable field lies in spatial
L².
A quantitative square-integral estimate using only the time weight and the uniform spatial square-integral bound.
Uniform finite kinetic energy gives square-integrability of every continuously weighted time average of a velocity.
In particular, the averaged difference of two finite-energy velocities
belongs to spatial L². The weight can equally be a continuous derivative of
a smooth time test function.
A uniform finite-energy bound also bounds every scalar coordinate's ordinary spatial square integral.
Coordinate square-integral bounds for the difference field.
A scalar coordinate of the averaged difference is in L², including
when the continuous weight is a derivative of a time test function.
Each nonlinear tensor component is jointly continuous on the slab.
Uniform finite kinetic energy gives spatial L¹ for each averaged
nonlinear tensor component.
A deliberately coarse bound for the L¹ norm of an L² pairing. It is
sufficient for the Fubini argument and uses no pointwise bound on either field.
The spatial L² pairing commutes with time averaging. Compact smooth
spatial tests are covered as a special case of a continuous L² test.
A complex scalar spatial test factors out of the time integral.
Fubini for a complex spatial test once the tested field has a uniform
spatial L¹ bound.
Uniformly L¹ real fields may be tested against every bounded continuous
complex function before interchanging the time and spatial integrals.
Spatial L² control makes a scalar field times a complex L² test
integrable, with a coarse bound sufficient for Fubini.
A uniformly square-integrable real field can be paired with a continuous
complex L² spatial test before interchanging time and space.
Pointwise recovery from compact temporal tests #
These are exactly the local smooth equation and uniform finite-energy hypotheses of the comparison argument.
- smooth_u : ContDiffOn ℝ (↑⊤) u (Comparison.slab 0 T)
- smooth_v : ContDiffOn ℝ (↑⊤) v (Comparison.slab 0 T)
- smooth_p : ContDiffOn ℝ (↑⊤) p (Comparison.slab 0 T)
- smooth_q : ContDiffOn ℝ (↑⊤) q (Comparison.slab 0 T)
- div_u (t : ℝ) : t ∈ Set.Ioo 0 T → ∀ (x : NavierStokes.ProblemStatement.Space), NavierStokes.ProblemStatement.spatialDivergence u t x = 0
- div_v (t : ℝ) : t ∈ Set.Ioo 0 T → ∀ (x : NavierStokes.ProblemStatement.Space), NavierStokes.ProblemStatement.spatialDivergence v t x = 0
- equation (t : ℝ) : t ∈ Set.Ioo 0 T → ∀ (x : NavierStokes.ProblemStatement.Space), NavierStokes.ProblemStatement.navierStokesResidual u p t x = NavierStokes.ProblemStatement.navierStokesResidual v q t x
- energy_u : ProblemStatement.UniformFiniteEnergy (Set.Icc 0 T) u
- energy_v : ProblemStatement.UniformFiniteEnergy (Set.Icc 0 T) v
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Velocity average, given by timeAverage T a (fun z => (u - v) z k).
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- NavierStokesR3.PressureRecovery.velocityAverage T a u v k = NavierStokesR3.Comparison.timeAverage T a fun (z : NavierStokesR3.ProblemStatement.SpaceTime) => ((u - v) z).ofLp k
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Tensor average, given by timeAverage T a (fun z => tensorDiff u v z.1 i j z.2).
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- One or more equations did not get rendered due to their size.
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Fubini for the actual canonical pressure pairing. The Riesz test is
bounded, so the uniform tensor L¹ bound controls the whole product.
Averaging the differentiated Poisson equation commutes with each compact tensor pairing. All derivatives remain on the compact test.
The averaged physical-minus-canonical pressure-gradient functional is harmonic on every compact real test, by the two actual Poisson identities.
The genuine H³ bound and compact harmonicity force the whole averaged
functional to vanish. No representative of the physical pressure on Schwartz
tests has been introduced.
The uniform tensor bound and spatial decay of a Riesz test give continuity of its canonical pairing in time, including the slab endpoints.
Every compact temporal test annihilates the difference between the physical and canonical pressure gradients, at a fixed compact spatial test.
Actual pressure-gradient recovery at every interior time. This equality is obtained from the equation and uniform finite energy, rather than assumed as a pressure normalization.
The explicit comparison-hypothesis form of pressure recovery. Only the spatial test is compactly supported; both velocities and both pressures are allowed on all of Euclidean space.
The compact test function in the pressure flux #
The identity φ² r = D(φ⁸)[w] places the localized pressure flux in the
commutator form. Its estimates use only the unweighted velocity energy and
the weighted velocity and gradient norms.
The scalar test function for the pressure commutator.
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The test belongs to L⁴, with the exact endpoint interpolation exponents.
Product differentiation before replacing the cutoff derivative norms by constants.
Only the weighted velocity derivative occurs in the pointwise bound.
The derivative is square integrable and controlled by weighted dissipation.
The actual test at radius R in the fixed cutoff family.
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A fixed constant for the derivative bound of the pressure test.
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- One or more equations did not get rendered due to their size.
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The actual pressure flux equals the canonical pressure flux #
The scalar gradient identification is supplied by the proved pressure recovery theorem. The only compact support in this identity is that of the cutoff.
From scalar pressure-gradient identification to the cutoff pressure flux #
This module is an integration-by-parts bridge. Its input is an explicit identification of every compact scalar pressure-gradient pairing. It does not assume a pressure-flux formula or any bound on the pressure at infinity.
The scalar compact test associated to one component of the weighted velocity.
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- NavierStokesR3.PressureFluxIdentity.weightedComponent χ w k x = χ x * (w x).ofLp k
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The compact flux test is the sum of the differentiated component tests.
The sum of all canonical pressure pairings is a complex-linear functional.
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- NavierStokesR3.PressureFluxIdentity.canonicalPressureLinear g hg = ∑ i : Fin 3, ∑ j : Fin 3, NavierStokesR3.PressureFunctionals.pressurePairLinear i j (g i j) ⋯
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Compact integration by parts turns the given scalar pressure-gradient identification into the actual cutoff pressure flux.
The pressure flux of the actual difference equation has the canonical Riesz-pairing representation, with no additional pressure hypothesis.
Weighted tensor bounds for the localized pressure #
The tensor difference is expanded around the reference velocity. Its two
cross terms use L³ of that velocity and L² of the difference; the quadratic
term uses the cutoff interpolation estimate. All norms remain finite explicitly.
Scalar Hölder with finite real-valued norms.
The scalar product of the two vector magnitudes belongs to L^(6/5).
The quadratic weighted difference has the endpoint interpolation bound.
The tensor identity uses the actual difference of the two velocities.
Pointwise domination is uniform in both tensor indices.
Compactness supplies finite weighted tensor norms without any growth assumption on either velocity.
The weighted tensor estimate used by the localized pressure argument. It has the same constant for every pair of indices.
The scalar test in the localized pressure flux.
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- NavierStokesR3.PressureFlux.fluxFunction χ w x = (fderiv ℝ χ x) (w x)
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The raw complex canonical pairing, with no pressure function selected.
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- NavierStokesR3.PressureFlux.canonicalFlux g f hf hc = ∑ i : Fin 3, ∑ j : Fin 3, NavierStokesR3.Comparison.pressurePair i j (g i j) (NavierStokesR3.PressureRecovery.realTest f hf hc)
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The compact Schwartz test used on the uncommuted side of the Riesz operator.
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The actual flux test Dχ_R[w], represented in the Schwartz space.
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Canonical flux for a time slice of the difference of two velocities.
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- One or more equations did not get rendered due to their size.
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The commutator integral in the heat-kernel estimate.
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- One or more equations did not get rendered due to their size.
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The fixed constant in the actual Riesz-test Sobolev inequality.
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Local pair constant, given by rieszSobolevConstant * PressureFluxTest.cutoffDerivativeConstant.
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The local part of one canonical pressure component is an actual integrable pairing.
The coefficient after fixing uniform bounds for the three data norms.
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Collecting constants uses only the fixed data-norm bounds, not the radius.
The fixed coefficient after combining the commutator and test-function bounds.
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- One or more equations did not get rendered due to their size.
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One actual canonical pressure component, with the three data norms explicit.
The full canonical flux with an explicit bound on each tensor component's L¹ norm.
One constant works for all radii and all smooth slices satisfying the fixed norm bounds.
The physical pressure flux has a single bound uniform in time and cutoff radius. All hypotheses on the pressure are exactly those already present in pressure recovery.