We study the Muskat problem for one fluid in an arbitrary dimension, bounded below by a flat bed and above by a free boundary given as a graph. In addition to a fixed uniform gravitational field, the fluid is acted upon by a generic force field in the bulk and an external pressure on the free boundary, both of which are posited to be in traveling wave form. We prove that, for sufficiently small force and pressure data in Sobolev spaces, there exists a locally unique traveling wave solution in Sobolev-type spaces. The free boundary of the traveling wave solutions is either periodic or asymptotically flat at spatial infinity. Moreover, we prove that small periodic traveling wave solutions induced by external pressure only are asymptotically stable. These results provide the first class of nontrivial stable solutions for the problem.
more »
« less
Global well‐posedness for the one‐phase Muskat problem
Abstract The free boundary problem for a two‐dimensional fluid permeating a porous medium is studied. This is known as the one‐phase Muskat problem and is mathematically equivalent to the vertical Hele‐Shaw problem driven by gravity force. We prove that if the initial free boundary is the graph of a periodic Lipschitz function, then there exists a global‐in‐time Lipschitz solution in the strong sense and it is the unique viscosity solution. The proof requires quantitative estimates for layer potentials and pointwise elliptic regularity in Lipschitz domains. This is the first construction of unique global strong solutions for the Muskat problem with initial data of arbitrary size.
more »
« less
- PAR ID:
- 10491949
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Communications on Pure and Applied Mathematics
- Volume:
- 76
- Issue:
- 12
- ISSN:
- 0010-3640
- Page Range / eLocation ID:
- 3912 to 3967
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
ABSTRACT This paper investigates a modification of the fictitious domain method with continuation in the lower‐order coefficients for the unsteady Navier‐Stokes equations governing the motion of an incompressible homogeneous fluid in a bounded 2D or 3D domain. The modification enables a solution‐dependent choice of the critical parameter. Global‐in‐time existence and convergence of a weak solution to the auxiliary problem are proved, and local‐in‐time existence and convergence of a unique strong solution are established. For the strong solution, a new higher‐order convergence rate estimate in the penalization parameter is obtained. The introduced framework allows us to apply a pointwise divergence‐free finite element method as a discretization technique, leading to a strongly mass conservative discrete fictitious domain method. A numerical example illustrates the performance of the method.more » « less
-
In this paper, we study the dynamics of fluids in porous media governed by Darcy’s law: the Muskat problem. We consider the setting of two immiscible fluids of different densities and viscosities under the influence of gravity in which one fluid is completely surrounded by the other. This setting is gravity unstable because along a portion of the interface, the denser fluid must be above the other. Surprisingly, even without capillarity, the circle-shaped bubble is a steady state solution moving with vertical constant velocity determined by the density jump between the fluids. Taking advantage of our discovery of this steady state, we are able to prove global in time existence and uniqueness of dynamic bubbles of nearly circular shapes under the influence of surface tension. We prove this global existence result for low regularity initial data. Moreover, we prove that these solutions are instantly analytic and decay exponentially fast in time to the circle.more » « less
-
Abstract We study surface capillary-gravity waves for viscous fluid flows governed by Darcy’s law. This includes flows in vertical Hele–Shaw cells and in porous media (the one-phase Muskat problem) with finite or infinite depth. The free boundary is acted upon by an external pressure posited to be in travelling wave form with an arbitrary periodic profile and an amplitude parameter. For any given wave speed, we first prove that there exists a unique local curve of small periodic travelling waves corresponding to small values of the parameter. Then we prove that as the parameter increases but could possibly be bounded, the curve belongs to a connected set of travelling waves. The set contains travelling waves that either have arbitrarily large gradients or are arbitrarily close to the rigid bottom in the finite depth case.more » « less
-
Abstract We study viscosity solutions to the classical one-phase problem and its thin counterpart. In low dimensions, we show that when the free boundary is the graph of a continuous function, the solution is the half-plane solution. This answers, in the salient dimensions, a one-phase free boundary analogue of Bernstein’s problem for minimal surfaces.As an application, we also classify monotone solutions of semilinear equations with a bump-type nonlinearity.more » « less
An official website of the United States government

