Hydrodynamics and Brownian motions of a spheroid near a rigid wall

Abstract Background The effects of arterial wall compliance on blood flow have been revealed using fluid-structure interaction in last decades. However, microcirculation is not considered in previous researches. In fact, microcirculation plays a key role in regulating blood flow. Therefore, it is very necessary to involve microcirculation in arterial hemodynamics. Objective The main purpose of the present study is to investigate how wall compliance affects the flow characteristics and to establish the comparisons of these flow variables with rigid wall when microcirculation is considered. Methods We present numerical modeling in arterial hemodynamics incorporating fluid-structure interaction and microcirculation. A novel outlet boundary condition is employed to prescribe microcirculation in an idealised model. Results The novel finding in this work is that wall compliance under the consideration of microcirculation leads to the increase of wall shear stress in contrast to rigid wall, contrary to the traditional result that wall compliance makes wall shear stress decrease when a constant or time dependent pressure is specified at an outlet. Conclusions This work provides the valuable study of hemodynamics under physiological and realistic boundary conditions and proves that wall compliance may have a positive impact on wall shear stress based on this model. This methodology in this paper could be used in real model simulations.

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Sticky Brownian Motions and a Probabilistic Solution to a Two-Point Boundary Value Problem

Mathematical Physics Analysis and Geometry ◽

10.1007/s11040-021-09383-5 ◽

2021 ◽

Vol 24 (2) ◽

Author(s):

Thu Dang Thien Nguyen

Keyword(s):

Boundary Value Problem ◽

Boundary Value ◽

Point Boundary ◽

Brownian Motions ◽

Probabilistic Solution

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Comparative 3D DEM simulations of sand–structure interfaces with similarly shaped clumps versus spheres with contact moments

Acta Geotechnica ◽

10.1007/s11440-021-01255-0 ◽

2021 ◽

Author(s):

A. Grabowski ◽

M. Nitka ◽

J. Tejchman

Keyword(s):

Particle Shape ◽

Friction Angle ◽

Rigid Wall ◽

Numerical Results ◽

Contact Forces ◽

Interface Roughness ◽

Interface Shear ◽

Dem Simulations ◽

Micropolar Continua ◽

Interface Behaviour

AbstractThree-dimensional simulations of a monotonic quasi-static interface behaviour between initially dense cohesionless sand and a rigid wall of different roughness during tests in a parallelly guided direct shear test under constant normal stress are presented. Numerical modelling was carried out by the discrete element method (DEM) using clumps in the form of convex non-symmetric irregularly shaped grains. The clumps had an aspect ratio of 1.5. A regular grid of triangular grooves (asperities) along the wall with a different height at the same distance was assumed. The numerical results with clumps were directly compared under the same conditions with our earlier DEM simulations using pure spheres with contact moments with respect to the peak and residual interface friction angle, width of the interface shear zone, ratio between grain slips and grain rotations, distribution of contact forces and stresses. The difference between the behaviour of clumps and pure spheres with contact moments proved to be noticeable in the post-peak regime due to a different particle shape. The rolling resistance model with pure spheres was proved to be limited for capturing particle shape effects. Three different boundary conditions along the interface were proposed for micropolar continua, considering grain rotations and grain slips, wall grain moments and wall grain forces, and normalized interface roughness. The numerical results in this paper offer a better understanding of the interface behaviour of granular bodies in DEM and FEM simulations.

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Dry granular avalanche impact force on a rigid wall of semi-infinite height

EPJ Web of Conferences ◽

10.1051/epjconf/201714003054 ◽

2017 ◽

Vol 140 ◽

pp. 03054 ◽

Cited By ~ 3

Author(s):

Adel Albaba ◽

Stéphane Lambert ◽

Thierry Faug

Keyword(s):

Impact Force ◽

Rigid Wall ◽

Infinite Height ◽

Granular Avalanche

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