REVIEW 2 major objections 4 minor 53 references
Dissipative Solutions to a Compressible Non-Newtonian Korteweg System with Density-Dependent Viscous Stress Tensor
T0 review · 2 major / 4 minor · reviewed 2026-08-03 · deepseek-v4-flash
Pith's one-line read This paper establishes that adding a special capillary (Korteweg) force yields global-in-time dissipative solutions for a compressible non-Newtonian fluid with density-dependent viscosity, and that these solutions inherit weak-strong unique
desk verdict Genuine extension of the Newtonian Korteweg dissipative-solution theory to non-Newtonian stresses, but the stated assumptions have a repairable gap for p=1 that the energy estimates do not cover. read the letter →
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
The reading
What carries the argument
The load-bearing object is the relative entropy functional E(t) in (2.1), combining kinetic energy relative to a test velocity, a capillary term κϱ|∇lnϱ−∇lnr|², and the convex pressure-entropy H(ϱ|r). The capillary term is special: by the Böhm identity div(ϱ∇²lnϱ)=2ϱ∇(Δ√ϱ/√ϱ), the energy controls 4κ|∇√ϱ|², which provides the H¹ compactness of √ϱ that the non-Newtonian stress alone cannot. The monotonicity of S and of the p-Laplacian regularizer is what allows passage to the limit in the nonlinear stress terms.
What would settle it
Solve the regularized system (3.1) on the 3D torus with ν=ε for two independent sequences ε→0, starting from the same smooth data, with S(Du)=|Du|^{p−2}Du for p=3 and γ=2; if the two limits differ while a classical strong solution exists for that data, the weak-strong uniqueness claim (Corollary 2.5) is false.
Extended reading notes
Core claim
The central claim, Theorem 1.2, is that under assumptions (1.4)–(1.5) on the stress tensor S and (1.6)–(1.7) on the pressure p, the system (1.1) admits a global-in-time dissipative solution for initial data satisfying √ϱ₀∈H¹, √ϱ₀u₀∈L², on the torus in dimensions 2 and 3. A dissipative solution here is defined through the relative entropy inequality (2.4) with admissible test functions (r,v); this notion is strong enough to imply weak-strong uniqueness (Corollary 2.5). The proof constructs weak solutions to an approximate system with ε∆ϱ and ν div(|Du|^{q−2}Du), derives the relative entropy inequality at the approximate level, and then passes ε,ν→0, with the approximation errors vanishing tha
Load-bearing premise
Everything hinges on the special capillary term κ div(ϱ∇²lnϱ): the energy controls H¹ of √ϱ only for this (or equivalent) structure, and for a general Korteweg stress K(ϱ)≠1/ϱ the compactness argument collapses.
Editorial extensions
If this is right
- Global dissipative solutions exist for a broad class of non-Newtonian compressible models (including power-law and regularized Bingham-type stresses) with density-dependent viscosity, where previously only local strong solutions or one-dimensional results were available.
- Any dissipative solution sharing initial data with a smooth strong solution must equal it, so the solution concept is unambiguous on the smooth regime.
- The relative entropy framework supplies a stability tool: dissipative solutions can be compared against any smooth approximate solution, opening the way to inviscid and large-viscosity limits, including the Euler–Korteweg system.
- Adding the special 1/ϱ capillarity is a physically motivated regularizer that breaks the obstruction to global existence for compressible non-Newtonian systems.
Reading between the lines
- The proof depends on the precise capillary form K(ϱ)=1/ϱ; a testable extension is whether the same relative-entropy scheme works for K(ϱ)=ϱ^β with β in some range, or whether the H¹ control of √ϱ is genuinely necessary.
- The weak-strong uniqueness suggests a numerical selection principle: any stable numerical method that converges to a dissipative solution will converge to the strong solution in the smooth regime, so the relative entropy could be used as an a posteriori error indicator.
- The definition via a concrete relative entropy inequality, rather than a measure-valued formulation, may allow a maximal-dissipation selection criterion; one could test whether the entropy-production term ϱS(Du):Du is maximal among all admissible limits.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper introduces a dissipative-solution framework for the periodic compressible Navier–Stokes–Korteweg system (1.1) with density-dependent non-Newtonian viscous stress. The main result, Theorem 1.2, asserts global-in-time existence of dissipative solutions for initial data satisfying (1.3), under growth/coercivity assumptions (1.4) and monotonicity (1.5) on S and pressure assumptions (1.6)–(1.7). The proof combines a Galerkin approximation of a regularized system with artificial viscosity and parabolic density diffusion (Section 3), a monotonicity passage for the nonlinear stress, a relative entropy inequality for the approximate system (Section 4), and a final limit ε,ν→0. A weak-strong uniqueness statement for dissipative solutions is also given (Corollary 2.5). The paper is careful and detailed, but the main theorem is stated more broadly than the proof supports.
Significance. If the stated result is repaired as suggested below, the paper would be a valuable extension of the dissipative-solution theory for compressible Korteweg flows from the Newtonian case of Bresch–Gisclon–Lacroix-Violet to non-Newtonian, density-dependent viscous stresses. The relative entropy inequality (2.4), the weak-strong uniqueness corollary, and the explicit multi-parameter approximation scheme are concrete and useful. The proof is largely self-contained, and the monotonicity/Galerkin construction for the approximate system is credible. The main value is conceptual: it identifies a solution concept with weak-strong uniqueness for a class for which Leray–Hoff weak solutions remain open.
major comments (2)
- [§1, assumptions (1.4)–(1.5); §3, energy identities (3.9), (3.17), (3.22)] The proof treats ∫ϱS(Du):Du as a nonnegative dissipation at every a priori stage, but (1.4)–(1.5) do not imply S(A):A ≥ 0 when p=1. The bound |S(A)|≤C|A|^{p-1} forces S(0)=0 only for p>1; for p=1 it does not. A monotone, bounded S with S(0)>0 and S(A)A<0 for small negative A satisfies (1.4)–(1.5) but makes the dissipation term signed, so the uniform bounds derived from (3.9) are not justified for the full stated class. Since the intended examples satisfy S(0)=0, the fix is local: add S(0)=0 (or S(A):A≥0 for all A) to the hypotheses. Without this, Theorem 1.2 is not established.
- [Theorem 1.2 and §3, Step 1 (approximation of initial data)] The theorem only assumes (1.3), i.e. √ϱ0∈H1 and √ϱ0u0∈L2. However the proof in Section 3 chooses √ϱ0,N→√ϱ0 in H1 and ϱ0,N→ϱ0 in L^γ, and E_N(0) is uniformly bounded only if ∫H(ϱ0) < ∞. Under (1.7), H(ϱ) is comparable to ϱ^γ, so one needs ϱ0∈L^γ. For γ>3, √ϱ0∈H1 only gives ϱ0∈L3, which is insufficient. Thus the statement of Theorem 1.2 (and the definition of the initial relative entropy in (2.4)) requires the additional hypothesis ϱ0∈L^γ, or equivalently E(0)<∞. As written, the theorem covers data for which the energy and the dissipative-solution inequality are not even defined.
minor comments (4)
- [§3, Step 3] The weak-limit notation is not fully defined: it is not immediately clear where the overline denotes the limit of S(Du_N) and where it denotes the limit of S(Du_N):Du_N. The monotonicity step leading to the nonnegativity of the S-term is terse; please spell out the standard Minty-type argument.
- [§4.1] The passage ε→0 in the relative entropy inequality is compressed. In particular, convergence of the terms in b(t) involving ∇lnϱε and the A1 term is only asserted; a short justification using the stated strong/weak convergences would improve readability.
- [Proposition 2.2] In the display before the final inequality, 'ϱ(∇lnϱ−lnr)' should read 'ϱ(∇lnϱ−∇lnr)'.
- [Appendix A.1] The heading contains a typo: 'Poncaré' should be 'Poincaré'.
Circularity Check
No significant circularity: the relative-entropy framework is self-cited, but the existence proof is a self-contained Galerkin/regularization derivation.
full rationale
The derivation chain is not circular. Theorem 1.2 is established by an explicit approximation scheme: the regularized system (3.1) is solved by Galerkin (Theorem 3.1), the energy identity (3.8) and its integrated form (3.9) give uniform estimates, the N→∞ limit is performed by compactness and the monotonicity method (Section 3, Step 3), yielding a weak solution of the regularized system with energy inequality (3.22). The relative entropy inequality (4.1) is then derived from the PDE and energy inequality (Propositions 4.1–4.2), and the ν,ε→0 passage (Section 4.1) uses only lower semicontinuity and the already-proved uniform bounds to obtain exactly (2.4), i.e., Definition 2.4. The target existence statement is never assumed. The relative entropy functional (2.1) and the overall strategy are attributed to the authors' prior papers [13,14], but the functional is written explicitly and all inequalities used in the limit are proved in the paper or cited to independent functional inequalities (e.g., (3.12)–(3.13) from [32,52,15,2]); no cited result contains Theorem 1.2. Corollary 2.5 is a one-line consequence of (2.4) with A_i=0 for a strong solution; this is the standard construction of dissipative solutions, not a circular reduction. The only concern raised by the reviewer—the missing S(0)=0 normalization for p=1—is a possible correctness gap in the sign of the dissipation term, not a circularity, and therefore does not affect this score.
Assumptions & free parameters
assumptions (5)
- domain assumption The pressure p satisfies p∈C([0,∞))∩C²((0,∞)), p(0)=0, p'>0, and aϱ^{γ-1}-b ≤ p'(ϱ) ≤ ϱ^{γ-1}/a + b, γ>1 (1.6)-(1.7).
- domain assumption The viscous stress S is differentiable, satisfies growth/coercivity (1.4) and monotonicity (1.5).
- domain assumption The Korteweg term is the special quantum-fluid form κ div(ϱ∇²lnϱ) = 2ϱ∇(Δ√ϱ/√ϱ), i.e., K(ϱ)=1/ϱ.
- standard math Standard functional analysis toolkit: Galerkin method, Schauder fixed point, Aubin–Lions–Simon compactness, Korn and Poincaré inequalities, lower semicontinuity of convex functionals.
- domain assumption Initial data satisfy ϱ₀≥0, √ϱ₀∈H¹, √ϱ₀u₀∈L².
Cite this review
Pith. "Pith review of Dissipative Solutions to a Compressible Non-Newtonian Korteweg System with Density-Dependent Viscous Stress Tensor." pith.science (2026). https://pith.science/paper/D6KHVIPV
@misc{pith2026260119442,
author = {Pith},
title = {Pith review of: Dissipative Solutions to a Compressible Non-Newtonian Korteweg System with Density-Dependent Viscous Stress Tensor},
year = {2026},
howpublished = {\url{https://pith.science/paper/D6KHVIPV}},
note = {Machine review of arXiv:2601.19442}
}
abstract
The main objective of this paper is to prove that if capillarity effect is taken into account then there exist dissipative solutions to a system describing viscoplastic compressible flows with density dependent viscosities in a periodic domain $\T^d$ with $d=2,3$. We calculate the relative entropy inequality and in consequence show existence of dissipative solutions and the weak-strong uniqueness for this system. Our result extends the recent result concerning the link between Euler--Korteweg and Navier--Stokes--Korteweg systems for Newtonian flows (when the viscosity depends on the density) [See D.~Bresch, M. Gisclon, I. Lacroix-Violet, {\it Arch. Rational Mech. Anal.} (2019)] to non-Newtonian flows.
Reference graph
Works this paper leans on
-
[13]
Bresch, M
D. Bresch, M. Gisclon, and I. Lacroix-Violet. On Navier–Stokes–Korteweg and Euler–Korteweg Systems: Application to Quantum Fluids Models.Arch. Ration. Mech. Anal., 233:975–1025, 2019
2019
-
[1]
Abbatiello, E
A. Abbatiello, E. Feireisl, and A. Novotný. Generalized solutions to models of compressible viscous fluids.Discrete Contin. Dyn. Syst., 41(1):1–28, 2021
2021
-
[2]
Alazard and D
T. Alazard and D. Bresch. Functional inequalities and strong Lyapunov functionals for free surface flows in fluid dynamics.Interfaces Free Bound., 26(1):1–30, 2024
2024
-
[3]
P. Antonelli, D. Bresch, and S. Spirito. Global weak solutions of the Navier–Stokes equations in one dimension. Preprint, arXiv:2502.17147, 2025
arXiv 2025
-
[4]
J. L. Baker, T. Barker, and J. M. N. T. Gray. A two-dimensional depth-averagedµ(i)-rheology for dense granular avalanches.J. Fluid Mech., 787:367–395, 2016
2016
-
[5]
Bardos and T
C. Bardos and T. T. Nguyen. Remarks in the inviscid limit for the compressible flows. InRecent advances in partial differential equations and applications, volume 666 ofContemp. Math., pages 55–67. Amer. Math. Soc., Providence, RI, 2016
2016
- [6]
-
[7]
Bresch and B
D. Bresch and B. Desjardins. Existence of global weak solutions for a 2D viscous shallow water equations and convergence to the quasi-geostrophic model.Comm. Math. Phys., 238:211–223, 07 2003
2003
Show all 53 references
-
[8]
Bresch and B
D. Bresch and B. Desjardins. Quelques modèles diffusifs capillaires de type korteweg.C. R. Acad. Sci. Paris, section mécanique, 332(11):881–886, 2004
2004
-
[9]
Bresch and B
D. Bresch and B. Desjardins. On the construction of approximate solutions for the 2D viscous shallow water model and for compressible Navier–Stokes models.J. Math Pures Appl., 86(4):362– 368, 2006
2006
-
[10]
Bresch, B
D. Bresch, B. Desjardins, and C.-K. Lin. On some compressible fluid models: Korteweg, lu- brication, and shallow water systems.Comm. Partial Differential Equations, 28(3-4):843–868, 2003
2003
-
[11]
Bresch, B
D. Bresch, B. Desjardins, and E. Zatorska. Two-velocity hydrodynamics in fluid mechanics: Part II Existence of globalκ-entropy solutions to the compressible Navier–Stokes systems with degenerate viscosities.J. Math. Pures Appl., 104(4):801–836, 2025
2025
-
[12]
Bresch, E
D. Bresch, E. D. Fernández-Nieto, I. R. Ionescu, and P. Vigneaux.Augmented Lagrangian Method and Compressible Visco-plastic Flows: Applications to Shallow Dense Avalanches, pages 57–89. Birkhäuser Basel, Basel, 2010
2010
-
[14]
Bresch, P
D. Bresch, P. Noble, and J.-P. Vila. Relative entropy for compressible Navier-Stokes equations with density dependent viscosities and various applications.ESAIM Proc., 58:40–57, 2017
2017
-
[15]
Bresch, A
D. Bresch, A. Vasseur, and C. Yu. Global existence of entropy-weak solutions to the compress- ible Navier–Stokes equations with non-linear density dependent viscosities.J. Eur. Math. Soc., 24(5):1791–1837, 2022
2022
-
[16]
Burtea and M
C. Burtea and M. Szlenk. Weak solutions to the navier–stokes equations for steady compressible non-Newtonian fluids.Nonlinear Analysis, 255:113774, 2025
2025
-
[17]
Chupin, T
L. Chupin, T. Dubois, M. Phan, and O. Roche. Pressure-dependent threshold in a granular flow: Numerical modeling and experimental validation.J. Non-Newton. Fluid Mech., 291:104529, 2021. 27
2021
-
[18]
Diening, M
L. Diening, M. R˘ užička, and J. Wolf. Existence of weak solutions for unsteady motions of general- ized Newtonian fluids.Annali della Scuola Normale Superiore di Pisa-Classe di Scienze, 9(1):1–46, 2010
2010
-
[19]
Elbar, P
C. Elbar, P. Gwiazda, J. Skrzeczkowski, and A. Świerczewska Gwiazda. From nonlocal Euler- Korteweg to local Cahn-Hilliard via the high-friction limit.J. Differential Equations, 422:264–305, 2025
2025
-
[20]
L. C. Evans and R. F. Gariepy.Measure Theory and Fine Properties of Functions. Studies in Advanced Mathematics. CRC Press, 1992
1992
-
[21]
Feireisl.Dynamics of viscous compressible fluids
E. Feireisl.Dynamics of viscous compressible fluids. Number 26 in Oxford Lecture Series in Mathematics and Its Applications. Oxford University Press, 2004
2004
-
[22]
Dissipativemeasure-valued solutions to the compressible navier–stokes system.Calc
E.Feireisl, P.Gwiazda, A.ŚwierczewskaGwiazda, andE.Wiedemann. Dissipativemeasure-valued solutions to the compressible navier–stokes system.Calc. Var. Partial Differential Equations, 55, 2016
2016
-
[23]
Feireisl, B
E. Feireisl, B. Jin, and A. Novotný. Relative entropies, suitable weak solutions, and weak-strong uniqueness for the compressible navier-stokes system.J. Math. Fluid Mech., 14(4):717–730, 2012
2012
-
[24]
Feireisl, X
E. Feireisl, X. Liao, and J. Málek. Global weak solutions to a class of non-Newtonian compressible fluids.Mathematical Methods in the Applied Sciences, 38(16), 2015
2015
-
[25]
Feireisl and A
E. Feireisl and A. Novotný.Singular Limits in Thermodynamics of Viscous Fluids. Number 2 in Advances in Mathematical Fluid Mechanics. Birkhäuser Cham, 2017
2017
-
[26]
Frehse, J
J. Frehse, J. Málek, and M. Steinhauer. On existence results for fluids with shear dependent viscosity. – Unsteady flows. InPartial differential equations: theory and numerical solution. Proceedings of the ICM’98 satellite conference, Prague, Czech Republic, August 10–16, 1998...
1998
-
[27]
Gisclon and I
M. Gisclon and I. Lacroix-Violet. About the barotropic compressible quantum Navier-Stokes equations.Nonlinear Anal., 128:106–121, 2015
2015
-
[28]
L. Guo, F. Li, and C. Yu. Dissipative solutions to the compressible isentropic Navier–Stokes equations.Commun. Math. Sci., 21(7), 2023
2023
-
[29]
Heida and J
M. Heida and J. Málek. On compressible Korteweg fluid-like materials.Internat. J. Engrg. Sci., 48(11):1313–1324, 2010. Special Issue in Honor of K.R. Rajagopal
2010
-
[30]
J. Hron, J. Málek, and K. R. Rajagopal. Simple flows of fluids with pressure–dependent viscosities. Proceedings of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences, 457(2011):1603–1622, 2001
2011
-
[31]
I. R. Ionescu, A. Mangeney, F. Bouchut, and O. Roche. Viscoplastic modeling of granular column collapse with pressure-dependent rheology.J. Non-Newton. Fluid Mech., 219:1–18, 2015
2015
-
[32]
A. Jüngel. Global weak solutions to compressible Navier–Stokes equations for quantum fluids. SIAM J. Math. Anal., 42(3):1025–1045, 2010
2010
-
[33]
Kalousek, V
M. Kalousek, V. Mácha, and Š. Nečasová. Local-in-time existence of strong solutions to a class of the compressible non-Newtonian Navier–Stokes equations.Mathematische Annalen, 384:1–33, 11 2021
2021
-
[34]
D. J. Korteweg. Sur la forme que prennent les équations du mouvement si l’on tient compte de forces capillaires causées par les variations de densité considérables mais continues et sur la théorie de la capillarité dans l’hypothèse d’une variation continue de la densité.Arch. ...
1901
-
[35]
Kwon and A
Y.-S. Kwon and A. Novotný. Dissipative solutions to compressible Navier–Stokes equations with general inflow–outflow data: Existence, stability and weak strong uniqueness.J. Math. Fluid Mech., 23, 2021
2021
-
[36]
Lacroix-Violet and A
I. Lacroix-Violet and A. Vasseur. Global weak solutions to the compressible quantum Navier- Stokes equation and its semi-classical limit.J. Math. Pure Appl., 114(9):191–210, 2018
2018
-
[37]
O. A. Ladyzhenskaya. New equations for the description of the motions of viscous incompressible fluids, and global solvability for their boundary value problems.Trudy Matematicheskogo Instituta Imeni VA Steklova, 102:85–104, 1967
1967
-
[38]
Li and Z
J. Li and Z. Xin. Global existence of weak solutions to the barotropic compressible Navier-Stokes flows with degenerate viscosities. Preprint, arXiv:1504.06826, 2015
2015 arXiv
-
[39]
Lions.Mathematical Topics in Fluid Mechanics Vol
P.-L. Lions.Mathematical Topics in Fluid Mechanics Vol. 1: Incompressible Models. Number 3 in Oxford Lecture Series in Mathematics and Its Applications. Oxford University Press, 1996
1996
-
[40]
Lions.Mathematical Topics in Fluid Mechanics, Vol
P.-L. Lions.Mathematical Topics in Fluid Mechanics, Vol. 2: Compressible Models. Oxford University Press, 1998
1998
-
[41]
Málek, J
J. Málek, J. Nečas, and M. R˘ užička. On the Non-Newtonian incompressible fluids.Mathematical Models and Methods in Applied Sciences, 03(01):35–63, Feb. 1993
1993
-
[42]
Málek and V
J. Málek and V. Průša.Derivation of Equations for Continuum Mechanics and Thermodynamics of Fluids, pages 1–70. Springer International Publishing, Cham, 2016
2016
-
[43]
Mamontov
A. Mamontov. Global solvability of the multidimensional navier-stokes equations of a compressible fluid with nonlinear viscosity. i.Siberian Mathematical Journal, 40(2):351–362, 1999
1999
-
[44]
Mamontov
A. Mamontov. Global solvability of the multidimensional navier-stokes equations of a compressible fluid with nonlinear viscosity. ii.Siberian Mathematical Journal, 40(3):541–555, 1999
1999
-
[45]
Mangeney-Castelnau, J.-P
A. Mangeney-Castelnau, J.-P. Vilotte, M. O. Bristeau, B. Perthame, F. Bouchut, C. Simeoni, and S. Yerneni. Numerical modeling of avalanches based on Saint Venant equations using a kinetic scheme.Journal of Geophysical Research: Solid Earth, 108(B11), 2003
2003
-
[46]
Mellet and A
A. Mellet and A. Vasseur. On the Barotropic Compressible Navier–Stokes Equations.Comm. Partial Differential Equations, 32(3):431–452, 2007
2007
-
[47]
Málek, J
J. Málek, J. Nečas, M. Rokyta, and M. Ruzicka.Weak and Measure-Valued Solutions to Evolu- tionary PDEs. Chapman and Hall/CRC, 1996
1996
-
[48]
Pokorn` y and M
M. Pokorn` y and M. Szlenk. Weak solutions for the Stokes system for compressible non-Newtonian fluids with unbounded divergence.Mathematical Methods in the Applied Sciences, 46(8):9736– 9750, 2023
2023
-
[49]
Rajagopal
K. Rajagopal. A generalization of the classical Euler and Korteweg fluids.Applications of Math- ematics, 68:1–13, 05 2023
2023
-
[50]
F. Sueur. On the inviscid limit for the compressible Navier-Stokes system in an impermeable bounded domain.J. Math. Fluid Mech., 16:163–178, 2014
2014
-
[51]
Vasseur and C
A. Vasseur and C. Yu. Existence of global weak solutions for 3D degenerate compressible Navier–Stokes equations.Invent. Math., 206, 12 2016
2016
-
[52]
A. F. Vasseur and C. Yu. Global weak solutions to the compressible quantum Navier–Stokes equations with damping.SIAM J. Math. Anal., 48(2):1489–1511, 2016
2016
-
[53]
J. Wolf. Existence of weak solutions to the equations of non-stationary motion of non-Newtonian fluids with shear rate dependent viscosity.Journal of Mathematical Fluid Mechanics, 9(1):104– 138, 2007. 29 Univ. Savoie Mont Blanc, CNRS, LAMA, 73000 Chambéry, France. Email addres...
2007
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