The Experts below are selected from a list of 240 Experts worldwide ranked by ideXlab platform
Maher Lagha - One of the best experts on this subject based on the ideXlab platform.
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Turbulent spots and waves in a model for plane Poiseuille Flow
Physics of Fluids, 2007Co-Authors: Maher LaghaAbstract:The structure of a turbulent spot in plane Poiseuille Flow is investigated using a model derived from the Navier–Stokes equations through a Galerkin method. The mean profile of the streamwise velocity inside the turbulent spot has the characteristic flat profile of a turbulent Poiseuille Flow. The waves developing at the wing tips of the spot have an asymmetric streamwise velocity with respect to the channel centerline, whereas their associated wall-normal velocity component is symmetric. On the outskirts of the spot, a large-scale Flow occupying the full gap between the plates is observed. It is characterized by a streamwise inFlow toward the spot and a spanwise outFlow from the spot. A detailed comparison with the numerical simulations and the experiments in the literature shows that these results are in fair agreement with the main features of the transitional plane Poiseuille Flow.
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Turbulent spots and waves in a model for plane Poiseuille Flow
Physics of Fluids, 2007Co-Authors: Maher LaghaAbstract:The structure of a turbulent spot in plane Poiseuille Flow is investigated using a model derived from the Navier-Stokes equations through a Galerkin method. The mean profile of the streamwise velocity inside the turbulent spot has the characteristic flat profile of a turbulent Poiseuille Flow. The waves developing at the wing tips of the spot have an asymmetric streamwise velocity with respect to the channel centerline, whereas their associated wall-normal velocity component is symmetric. On the outskirts of the spot, a large-scale Flow occupying the full gap between the plates is observed. It is characterized by a streamwise inFlow toward the spot and a spanwise outFlow from the spot. A detailed comparison with the numerical simulations and the experiments in the literature shows that these results are in fair agreement with the main features of the transitional plane Poiseuille Flow. © 2007 American Institute of Physics.
Takaaki Nishida - One of the best experts on this subject based on the ideXlab platform.
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traveling waves bifurcating from plane Poiseuille Flow of the compressible navier stokes equation
Archive for Rational Mechanics and Analysis, 2019Co-Authors: Yoshiyuki Kagei, Takaaki NishidaAbstract:Plane Poiseuille Flow in viscous compressible fluid is known to be asymptotically stable if Reynolds number R and Mach number M are sufficiently small. On the other hand, for R and M being not necessarily small, an instability criterion for plane Poiseuille Flow is known, and the criterion says that, when R increases, a pair of complex conjugate eigenvalues of the linearized operator cross the imaginary axis. In this paper it is proved that a spatially periodic traveling wave bifurcates from plane Poiseuille Flow when the critical eigenvalues cross the imaginary axis.
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Traveling Waves Bifurcating from Plane Poiseuille Flow of the Compressible Navier–Stokes Equation
Archive for Rational Mechanics and Analysis, 2018Co-Authors: Yoshiyuki Kagei, Takaaki NishidaAbstract:Plane Poiseuille Flow in viscous compressible fluid is known to be asymptotically stable if Reynolds number R and Mach number M are sufficiently small. On the other hand, for R and M being not necessarily small, an instability criterion for plane Poiseuille Flow is known, and the criterion says that, when R increases, a pair of complex conjugate eigenvalues of the linearized operator cross the imaginary axis. In this paper it is proved that a spatially periodic traveling wave bifurcates from plane Poiseuille Flow when the critical eigenvalues cross the imaginary axis.
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instability of plane Poiseuille Flow in viscous compressible gas
Journal of Mathematical Fluid Mechanics, 2015Co-Authors: Yoshiyuki Kagei, Takaaki NishidaAbstract:Instability of plane Poiseuille Flow in viscous compressible gas is investigated. A condition for the Reynolds and Mach numbers is given in order for plane Poiseuille Flow to be unstable. It turns out that plane Poiseuille Flow is unstable for Reynolds numbers much less than the critical Reynolds number for the incompressible Flow when the Mach number is suitably large. It is proved by the analytic perturbation theory that the linearized operator around plane Poiseuille Flow has eigenvalues with positive real part when the instability condition for the Reynolds and Mach numbers is satisfied.
Brian Straughan - One of the best experts on this subject based on the ideXlab platform.
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Stability of Poiseuille Flow in a Porous Medium
Advances in Mathematical Fluid Mechanics, 2009Co-Authors: Antony A. Hill, Brian StraughanAbstract:We study the linear instability and nonlinear stability of Poiseuille Flow in a porous medium of Brinkman type. The equivalent of the Orr-Sommerfeld eigenvalue problem is solved numerically. Difficulties with obtaining the spectrum of the porous Orr-Sommerfeld equation are discussed. The nonlinear energy stability eigenvalue problems are solved for x, z and y, z disturbances.
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Instability of Poiseuille Flow in a fluid overlying a porous layer
Journal of Fluid Mechanics, 2006Co-Authors: Min-hsing Chang, Falin Chen, Brian StraughanAbstract:The problem of Poiseuille Flow in a fluid overlying a porous medium saturated with the same fluid is studied. A careful linear instability analysis is carried out. It is shown that there are three modes of instability, two belong to one eigenvalue and persist in small ranges of parameters, while beyond these parameter ranges a third corresponding to another eigenvalue prevails. These three modes are of different stability characteristics, but are triggered by the shear stress of the Poiseuille Flow in the fluid layer.
Yoshiyuki Kagei - One of the best experts on this subject based on the ideXlab platform.
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traveling waves bifurcating from plane Poiseuille Flow of the compressible navier stokes equation
Archive for Rational Mechanics and Analysis, 2019Co-Authors: Yoshiyuki Kagei, Takaaki NishidaAbstract:Plane Poiseuille Flow in viscous compressible fluid is known to be asymptotically stable if Reynolds number R and Mach number M are sufficiently small. On the other hand, for R and M being not necessarily small, an instability criterion for plane Poiseuille Flow is known, and the criterion says that, when R increases, a pair of complex conjugate eigenvalues of the linearized operator cross the imaginary axis. In this paper it is proved that a spatially periodic traveling wave bifurcates from plane Poiseuille Flow when the critical eigenvalues cross the imaginary axis.
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Traveling Waves Bifurcating from Plane Poiseuille Flow of the Compressible Navier–Stokes Equation
Archive for Rational Mechanics and Analysis, 2018Co-Authors: Yoshiyuki Kagei, Takaaki NishidaAbstract:Plane Poiseuille Flow in viscous compressible fluid is known to be asymptotically stable if Reynolds number R and Mach number M are sufficiently small. On the other hand, for R and M being not necessarily small, an instability criterion for plane Poiseuille Flow is known, and the criterion says that, when R increases, a pair of complex conjugate eigenvalues of the linearized operator cross the imaginary axis. In this paper it is proved that a spatially periodic traveling wave bifurcates from plane Poiseuille Flow when the critical eigenvalues cross the imaginary axis.
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instability of plane Poiseuille Flow in viscous compressible gas
Journal of Mathematical Fluid Mechanics, 2015Co-Authors: Yoshiyuki Kagei, Takaaki NishidaAbstract:Instability of plane Poiseuille Flow in viscous compressible gas is investigated. A condition for the Reynolds and Mach numbers is given in order for plane Poiseuille Flow to be unstable. It turns out that plane Poiseuille Flow is unstable for Reynolds numbers much less than the critical Reynolds number for the incompressible Flow when the Mach number is suitably large. It is proved by the analytic perturbation theory that the linearized operator around plane Poiseuille Flow has eigenvalues with positive real part when the instability condition for the Reynolds and Mach numbers is satisfied.
Chaouqi Misbah - One of the best experts on this subject based on the ideXlab platform.
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Symmetry breaking of vesicle shapes in Poiseuille Flow
Physical Review E : Statistical Nonlinear and Soft Matter Physics, 2011Co-Authors: Alexander Farutin, Chaouqi MisbahAbstract:Vesicle behavior under unbounded axial Poiseuille Flow is studied analytically. Our study reveals subtle features of the dynamics. It is established that there exists a stable off-centerline steady-state solution for low enough Flow strength. This solution appears as a symmetry-breaking bifurcation upon lowering the Flow strength and includes slipper shapes, which are characteristic of red blood cells in the microvasculature. A stable axisymmetric solution exists for any Flow strength provided the excess area is small enough. It is shown that the mechanism of the symmetry breaking depends on the geometry of the Flow: The bifurcation is subcritical in axial Poiseuille Flow and supercritical in planar Flow.
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Lateral migration of a two-dimensional vesicle in unbounded Poiseuille Flow.
Physical Review E : Statistical Nonlinear and Soft Matter Physics, 2008Co-Authors: Badr Kaoui, Chaouqi Misbah, G. H. Ristow, Isabelle Cantat, Walter ZimmermannAbstract:The migration of a suspended vesicle in an unbounded Poiseuille Flow is investigated numerically in the low Reynolds number limit. We consider the situation without viscosity contrast between the interior of the vesicle and the exterior. Using the boundary integral method we solve the corresponding hydrodynamic Flow equations and track explicitly the vesicle dynamics in two dimensions. We find that the interplay between the nonlinear character of the Poiseuille Flow and the vesicle deformation causes a cross-streamline migration of vesicles toward the center of the Poiseuille Flow. This is in a marked contrast with a result [L. G. Leal, Annu. Rev. Fluid Mech. 12, 435 (1980)] according to which the droplet moves away from the center (provided there is no viscosity contrast between the internal and the external fluids). The migration velocity is found to increase with the local capillary number (defined by the time scale of the vesicle relaxation toward its equilibrium shape times the local shear rate), but reaches a plateau above a certain value of the capillary number. This plateau value increases with the curvature of the parabolic Flow profile. We present scaling laws for the migration velocity.
