Abstract:We consider the steady Bingham flow in a two-dimensional thin Y-like shaped structure, with no-slip boundary conditions and under the action of given external forces. After passage to the limit with respect to a small parameter related to the thickness of the domain, we obtain three uncoupled problems. Each of these problems describes an anisotropic flow, corresponding to a lower-dimensional “Bingham-like” constitutive law. These results are in accordance with the engineering models.
“…For the reader's convenience we remind the definitions of the tube structure and its graph given in [13]. 3, and e 1 , e 2 , ..., e M be M closed segments each connecting two of these points (i.e., each e j = O ij O kj , where i j , k j ∈ {1, ..., N }, i j ̸ = k j ). All points O i are supposed to be the ends of some segments e j .…”
Section: Thin Tube Structure and Its Graphmentioning
confidence: 99%
“…Nonlinear equations on the graph are generated by the problems in thin tube structures for viscous flows with non-Newtonian rheology. The case of the Stokes equations with the shear rate dependent viscosity was considered in the set of three papers [21,22,23], where the complete asymptotic expansion of the solution was constructed (also see [3,4] for the Bingham law rheology and [9] for the power law rheology). In particular, in [22] a nonlinear equation on the graph is studied.…”
Section: Introduction and Main Definitionsmentioning
The dimension reduction for the viscous flows in thin tube structures leads to equations on the graph for the macroscopic pressure with Kirchhoff type junction conditions in the vertices. Non-Newtonian rheology of the flow generates nonlinear equations on the graph. A new numerical method for second order nonlinear differential equations on the graph is introduced and numerically tested.
“…For the reader's convenience we remind the definitions of the tube structure and its graph given in [13]. 3, and e 1 , e 2 , ..., e M be M closed segments each connecting two of these points (i.e., each e j = O ij O kj , where i j , k j ∈ {1, ..., N }, i j ̸ = k j ). All points O i are supposed to be the ends of some segments e j .…”
Section: Thin Tube Structure and Its Graphmentioning
confidence: 99%
“…Nonlinear equations on the graph are generated by the problems in thin tube structures for viscous flows with non-Newtonian rheology. The case of the Stokes equations with the shear rate dependent viscosity was considered in the set of three papers [21,22,23], where the complete asymptotic expansion of the solution was constructed (also see [3,4] for the Bingham law rheology and [9] for the power law rheology). In particular, in [22] a nonlinear equation on the graph is studied.…”
Section: Introduction and Main Definitionsmentioning
The dimension reduction for the viscous flows in thin tube structures leads to equations on the graph for the macroscopic pressure with Kirchhoff type junction conditions in the vertices. Non-Newtonian rheology of the flow generates nonlinear equations on the graph. A new numerical method for second order nonlinear differential equations on the graph is introduced and numerically tested.
“…A review of works related to problems of diffusion-convection in thin tubular structures is given in [24]. Here we mention the works [5,7,21] that we discovered while working on this article. The steady Bingham flow was studied in a two-dimensional thin Y -like shaped structure and three uncoupled problems were obtained in the limit in [7]; in the other ones, the incompressible stationary fluids flowing through multiple pipe systems were studied via asymptotic analysis.…”
mentioning
confidence: 99%
“…Here we mention the works [5,7,21] that we discovered while working on this article. The steady Bingham flow was studied in a two-dimensional thin Y -like shaped structure and three uncoupled problems were obtained in the limit in [7]; in the other ones, the incompressible stationary fluids flowing through multiple pipe systems were studied via asymptotic analysis. Another related scenario occurs for thin debris-filled wellbores or when modelling effective surface roughness in any kind of tubes and channels with varying aperture (see e.g.…”
A steady-state convection-diffusion problem with a small diffusion of order O ( ε ) is considered in a thin three-dimensional graph-like junction consisting of thin cylinders connected through a domain (node) of diameter O ( ε ), where ε is a small parameter. Using multiscale analysis, the asymptotic expansion for the solution is constructed and justified. The asymptotic estimates in the norm of Sobolev space H 1 as well as in the uniform norm are proved for the difference between the solution and proposed approximations with a predetermined accuracy with respect to the degree of ε.
The steady state Stokes-Brinkman equations in a thin tube structure is considered. The Brinkman term differs from zero only in small balls near the ends of the tubes. The boundary conditions are: given pressure at the inflow and outflow of the tube structure and the no slip boundary condition on the lateral boundary. The complete asymptotic expansion of the problem is constructed. The error estimates are proved. The method of partial asymptotic dimension reduction is introduced for the Stokes-Brinkman equations and justified by an error estimate. This method approximates the main problem by a hybrid dimension problem for the Stokes-Brinkman equations in a reduced domain. Asymptotic analysis is applied to determine the permeability of a tissue with a roll of blood vessels.
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