A vortex free boundary problem: Existence and uniqueness results for the physical solution

1997 ◽  
Vol 173 (1) ◽  
pp. 279-298
Author(s):  
Alessandro Torelli
Author(s):  
John Van Der Hoek ◽  
C. J. Barnes ◽  
J. H. Knight

AbstractA field comprising uniformly porous soil overlying an impervious subsoil is drained through equally spaced tile drains placed on the boundary between the two layers of soil. When this field is subject to uniform irrigation, a free boundary forms in the porous region above the zone of saturation. We study the free boundary value problem which thus arises using the theory of variational inequalities. Existence and uniqueness results are established.


Author(s):  
Henri Berestycki ◽  
Regis Monneau ◽  
José A. Scheinkman

We consider an evolution non-local free boundary problem that arises in the modelling of speculative bubbles. The solution of the model is the speculative component in the price of an asset. In the framework of viscosity solutions, we show the existence and uniqueness of the solution. We also show that the solution is convex in space, and establish several monotonicity properties of the solution and of the free boundary with respect to parameters of the problem. To study the free boundary, we use, in particular, the fact that the odd part of the solution solves a more standard obstacle problem. We show that the free boundary is and describe the asymptotics of the free boundary as c , the cost of transacting the asset, goes to zero.


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