Computer-assisted Analysis and Applications of Moving Interfaces in Incompressible Flows

Project Information

CAMINFLOW

Grant agreement ID: 101031111

DOI

10.3030/101031111

Project terminated on 30 November 2022

EC signature date 6 April 2021

Start date 1 September 2021

End date 31 August 2023

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 160 932,48

EU contribution

€ 160 932,48

Coordinated by

UNIVERSITAT DE BARCELONA
Spain

Periodic Reporting for period 1 - CAMINFLOW (Computer-assisted Analysis and Applications of Moving Interfaces in Incompressible Flows)

Reporting period: 2021-09-01 to 2023-08-31

Summary of the context and overall objectives of the project

Most physical phenomena, from fluids to biology, passing through economics or general relativity, are governed by Partial Differential Equations (PDEs). The lack of a rigorous understanding of these equations forces engineers and physicists to rely on heuristics, approximations and available data, which has undesirable implications in terms of efficiency and cost. Despite the diverse fields that give rise to PDEs, there is one conspicuous and fundamental question that unifies all of them: do solutions break down? If the model is correct, one expects that, given certain initial conditions, the evolution of the system is determined and predictable. However, whether solutions corresponding to smooth initial conditions propagate their regularity for all time or, on the contrary, form finite-time singularities is yet unknown for the majority of nonlinear PDE. In particular, among classical physics, fluid mechanics and the mystery of turbulence is an outstanding example, belonging to the exclusive list of Clay Millenium Problems.
To delve into this regularity versus finite-time singularity issues, the evolution of fluid interfaces provides very rich scenarios. One could think for example in the smooth steady translation of small waves in the sea versus the turbulent wave breaking process near the seashore. Moreover, the techniques needed for their study are the basis to study the more complex case of fluid-structure moving interfaces, with strong implications in the modeling of bio-structures such as cells in the blood.
In this project, we proposed to answer these questions for several scenarios: surface diffusion for a solid; movement of fluids in a porous medium (such as petroleum); and elastic immersed interfaces (vesicles). In addition to state-of-the-art mathematical methods to analyze these problems, this proposal includes the possibility of using computer-assisted proofs whenever traditional methods are not sufficient.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The project has resulted in three papers:
1. E. Garcia-Juarez, J. Gómez-Serrano, H. Q. Nguyen, B. Pausader. Self-similar solutions for the Muskat equation. Advances in Mathematics, 399, (2022)
2. F. Gancedo, E. Garcia-Juarez. Quantitative Hölder Estimates for Even Singular Integral Operators on Patches. Journal of Functional Analysis, 283 (9), (2022).
3. F. Gancedo, E. Garcia-Juarez. Global Regularity of 2D N-S Free Boundary with Small Viscosity Contrast. To appear in Annales de l’Institut Henri Poincaré C, Analyse Non Linéaire, (2023),
and two more papers will be submitted to journals in the following month. Two additional works are expected to be completed and submitted to journals within six months.

Paper 1 is directly related to the objective about the evolution of fluids in a porous medium. The objective proposed (proof of curvature blow-up in the Muskat equation) turned out to be false, but the work on this point has resulted in the proof of the opposite fact (desingularization of corners). The ER has been invited to give talks about this result at seminars in ICERM, Brown University, Chicago and at the RSME bi-annual conference. In addition to the aforementioned paper, the ER in collaboration with J. Gomez-Serrano, S. Haziot and B. Pausader, has extended the methods to deal with multiple moving corners (result under preparation;) the co-author S. Haziot has been invited to give a talk about it at the prestigious BIRS center at Banff. Moreover, the technique in Paper 1 is now being used to obtain the first proof of finite-time singularities for a closely related equation.
The ER, in collaboration with P.C. Kuo, Y. Mori, and R. Strain, has proved the local-in-time existence for the problem of an inextensible string immersed in a Stokes fluid, and this result is now under preparation. Moreover, the ER and collaborators have obtained the local well-posedness for the problem of a three-dimensional elastic membrane immersed in a fluid, which should serve as a first step to extend the inextensible string result to 3D models for vesicles.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The ideas introduced to obtain the first self-similar solutions to the Muskat problem about fluids in a porous medium are now being used to find a finite-time singularity in a related equation, which would provide a major result in the field. Moreover, the techniques developed to deal with multiple moving corners are very flexible and could be used to study more general settings, including those with more real effects such as surface tension or fluids with different viscosities.
The works on elastic immersed membranes and inextensible strings, to be submitted, will each of them open the way to study further questions such as global in time behavior, appearance of bifurcation phenomena, convergence of numerical methods, to name a few.

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