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B U Felderhof - One of the best experts on this subject based on the ideXlab platform.
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velocity relaxation of a porous sphere immersed in a viscous incompressible fluid
Journal of Chemical Physics, 2014Co-Authors: B U FelderhofAbstract:Velocity relaxation of a spherically symmetric polymer, immersed in a viscous incompressible fluid, and after a sudden small impulse or a sudden twist from a state of rest, is studied on the basis of the linearized Navier-Stokes equations with an added Darcy type drag term. Explicit expressions for the translational and rotational velocity relaxation functions of the polymer and for the flow pattern of the fluid are derived for a uniform permeable sphere. Surprisingly, it is found that the added mass vanishes. For fairly large values of the ratio of sphere radius to the screening length characterizing the permeability, the velocity relaxation functions in the short and intermediate time regime differ significantly from that of a sphere with No-Slip Boundary Condition. At long times, both relaxation functions show universal power law behavior.
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broadside mobility of a disk in a viscous fluid near a plane wall with no slip Boundary Condition
Journal of Chemical Physics, 2012Co-Authors: B U FelderhofAbstract:The broadside motion of a disk in a viscous fluid towards a planar wall with No-Slip Boundary Condition is studied on the basis of the steady-state Stokes equations. It is shown that flow velocity and pressure of the fluid can be found conveniently from a superposition of elementary complex stream functions. The two amplitude functions characterizing the superposition are found from the numerical solution of a pair of integral equations for the axial and radial velocity components at the disk. The numerical procedure converges fast, provided the distance to the plane is not much smaller than the radius of the disk. For small distance the flow is well approximated by lubrication theory.
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flow of a viscous compressible fluid produced in a circular tube by an impulsive point source
Journal of Fluid Mechanics, 2011Co-Authors: B U Felderhof, G OomsAbstract:The flow of a viscous compressible fluid in a circular tube generated by a sudden impulse at a point on the axis is studied on the basis of the linearized Navier–Stokes equations. A No-Slip Boundary Condition is assumed to hold on the wall of the tube. An efficient numerical scheme has been developed for the calculation of flow velocity and pressure disturbance as a function of position and time.
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transient flow of a viscous compressible fluid in a circular tube after a sudden point impulse
Journal of Fluid Mechanics, 2009Co-Authors: B U FelderhofAbstract:The flow of a viscous incompressible fluid in a circular tube generated by a sudden impulse on the axis is studied on the basis of the linearized Navier―Stokes equations. A No-Slip Boundary Condition is assumed to hold on the wall of the tube. At short time the flow is irrotational and may be described by a potential which varies with the square root of time. At later times there is a sequence of moving and decaying vortex rings. At long times the flow velocity decays with an algebraic long-time tail. The impulse generates a time-dependent pressure difference between the ends of the tube.
Steve Granick - One of the best experts on this subject based on the ideXlab platform.
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limits of the hydrodynamic no slip Boundary Condition
Physical Review Letters, 2002Co-Authors: Yingxi Zhu, Steve GranickAbstract:A controversial point in fluid dynamics is to distinguish the relative importance of surface roughness and fluid-surface intermolecular interactions in determining the Boundary Condition. Here hydrodynamic forces were compared for flow of Newtonian fluids past surfaces of variable roughness but similar, poorly wetted, surface chemistry. The critical shear stress and shear rate to observe deviations from predictions using the No-Slip Boundary Condition increased nearly exponentially with increasing roughness and diverged at $\ensuremath{\approx}6$ nm rms roughness. We conclude that local intermolecular interactions dominated when the surface was very smooth, but roughness dominated otherwise. This quantifies the limits of both ideas.
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No-Slip Boundary Condition switches to partial slip when fluid contains surfactant
Langmuir, 2002Co-Authors: Yingxi Zhu, Steve GranickAbstract:Physisorbed surfactant can change the hydrodynamic Boundary Condition of oil flow from “stick” to “partial slip”, provided that the shear stress on the wall exceeds a threshold level that decreases with increasing surface coverage of surfactant. To demonstrate this, Newtonian alkane fluids (octane, dodecane, tetradecane) were placed between molecularly smooth surfaces that were either wetting (muscovite mica) or rendered partially wetted by adsorption of surfactant (0.2 or 0.1 wt % hexadecylamine). The surface spacing was vibrated at spacings so large that the fluid responded as a continuum. The resulting hydrodynamic forces agreed with predictions from the No-Slip Boundary Condition when flow rate, peak velocity normalized by surface spacing, was low but implied partial slip when it exceeded a critical level. In other words, the “slip length” depended on reduced velocity. When the reduced velocity was sufficiently high, a plateau shear stress was observed, ≈1.3 N m-2 for 0.2 wt % hexadecylamine, but also...
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rate dependent slip of newtonian liquid at smooth surfaces
Physical Review Letters, 2001Co-Authors: Steve GranickAbstract:: Newtonian fluids were placed between molecularly smooth surfaces whose spacing was vibrated at spacings where the fluid responded as a continuum. Hydrodynamic forces agreed with predictions from the No-Slip Boundary Condition only provided that flow rate (peak velocity normalized by spacing) was low, but implied partial slip when it exceeded a critical level, different in different systems, correlated with contact angle (surface wettability). With increasing flow rate and partially wetted surfaces, hydrodynamic forces became up to 2-4 orders of magnitude less than expected by assuming the No-Slip Boundary Condition that is commonly stated in textbooks.
William A. Ducker - One of the best experts on this subject based on the ideXlab platform.
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no slip hydrodynamic Boundary Condition for hydrophilic particles
"Proceedings" of "OilGasScientificResearchProjects" Institute SOCAR, 2011Co-Authors: Christopher D. F. Honig, William A. DuckerAbstract:We describe measurement and interpretation of the force acting on a smooth hydrophilic glass particle during rapid (1 - 100 mms -1) approach to, and separation from, a hydrophilic glass plate in viscous concentrated aqueous sucrose solutions (0:001 Pas
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squeeze film lubrication in silicone oil experimental test of the no slip Boundary Condition at solid liquid interfaces
Journal of Physical Chemistry C, 2008Co-Authors: Christopher D. F. Honig, William A. DuckerAbstract:The hydrodynamic force between a spherical glass particle (radius ∼ 10 μm) and a smooth, flat glass plate in Newtonian silicone oil (viscosity, η ∼ 95 mPa s) was measured using the atomic force microscopy (AFM) colloidal probe technique and was compared to Reynolds lubrication theory. When the particle and plate were coated with a hydrophobic silane, the measured forces were consistent with Reynolds lubrication theory without the need to introduce the concept of a slip length. When the particle was hydrophilic, the results were more variable, sometimes being consistent with the No-Slip Boundary Condition and sometimes being better fitted by invoking a constant slip length (up to 33 nm). The hydrophilic system was not well characterized because the hydrophilic solid may have entrained or attracted a layer of water (η = 0.001 Pa s) of unknown thickness, which would lubricate the flow and explain the apparent slip length. In addition, all AFM force measurements suffer from the problem that the solids occasio...
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No-Slip hydrodynamic Boundary Condition for hydrophilic particles.
Physical review letters, 2007Co-Authors: Christopher D. F. Honig, William A. DuckerAbstract:We describe measurement and interpretation of the force acting on a smooth hydrophilic glass particle during rapid ($1--100\text{ }\text{ }\ensuremath{\mu}\mathrm{m}\text{ }{\mathrm{s}}^{\ensuremath{-}1}$) approach to, and separation from, a hydrophilic glass plate in viscous concentrated aqueous sucrose solutions ($0.001\text{ }\text{ }\mathrm{Pa}\text{ }\mathrm{s}l\ensuremath{\eta}l0.090\text{ }\text{ }\mathrm{Pa}\text{ }\mathrm{s}$). We find that the force is accurately described by Reynolds lubrication theory with a No-Slip Boundary Condition, even at maximum strain rates of up to $250\text{ }000\text{ }\text{ }{\mathrm{s}}^{\ensuremath{-}1}$. Compared to earlier studies of hydrodynamic forces on small particles, we reduce the uncertainty in the absolute particle-plate separation by using an evanescent-wave measurement of the separation.
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Thin Film Lubrication for Large Colloidal Particles: Experimental Test of the No-Slip Boundary Condition
The Journal of Physical Chemistry C, 2007Co-Authors: Christopher D. F. Honig, William A. DuckerAbstract:We have measured the hydrodynamic force between a particle (R ≈ 10 μm) and a smooth, flat plate using Atomic Force Microscopy in Newtonian, concentrated sucrose−water solutions for both hydrophilic solids (hydroxyl-terminated silica) and hydrophobic solids (methyl-terminated silica or graphite). For all cases, the measured force is consistent with Reynolds lubrication theory with the No-Slip Boundary Condition and a constant viscosity. Our error in determining the slip length varies according to the particular experiment, but is about 2 nm. We have restricted our analysis to Conditions where Reynolds lubrication is valid, i.e., films that are much greater than the molecular diameter of the fluid. Our experimental method contains two significant improvements over earlier work: the use of much stiffer cantilever springs and the use of evanescent wave scattering as an independent check of the zero of separation. Our results are consistent with molecular dynamics simulations for thinner films and greater she...
Yasunori Maekawa - One of the best experts on this subject based on the ideXlab platform.
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on the inviscid limit problem of the vorticity equations for viscous incompressible flows in the half plane
Communications on Pure and Applied Mathematics, 2014Co-Authors: Yasunori MaekawaAbstract:We consider the Navier-Stokes equations for viscous incompressible flows in the half-plane under the No-Slip Boundary Condition. By using the vorticity formulation we prove the local-in-time convergence of the Navier-Stokes flows to the Euler flows outside a Boundary layer and to the Prandtl flows in the Boundary layer in the inviscid limit when the initial vorticity is located away from the Boundary. © 2014 Wiley Periodicals, Inc.
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a liouville theorem for the planer navier stokes equations with the no slip Boundary Condition and its application to a geometric regularity criterion
arXiv: Analysis of PDEs, 2013Co-Authors: Yoshikazu Giga, Penyuan Hsu, Yasunori MaekawaAbstract:We establish a Liouville type result for a backward global solution to the Navier-Stokes equations in the half plane with the No-Slip Boundary Condition. No assumptions on spatial decay for the vorticity nor the velocity field are imposed. We study the vorticity equations instead of the original Navier-Stokes equations. As an application, we extend the geometric regularity criterion for the Navier-Stokes equations in the three-dimensional half space under the No-Slip Boundary Condition.
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solution formula for the vorticity equations in the half plane with application to high vorticity creation at zero viscosity limit
Advances in Differential Equations, 2013Co-Authors: Yasunori MaekawaAbstract:We consider the Navier--Stokes equations for viscous incompressible flows in the half plane under the No-Slip Boundary Condition. In this paper we first establish a solution formula for the vorticity equations through the appropriate vorticity formulation. The formula is then applied to establish the asymptotic expansion of vorticity fields at $\nu\rightarrow 0$ that holds at least up to the time $c\nu^{1/3}$, where $\nu$ is the viscosity coefficient and $c$ is a constant. As a consequence, we get a natural sufficient Condition on the initial data for the vorticity to blow up at the inviscid limit, together with explicit estimates.
Petros Koumoutsakos - One of the best experts on this subject based on the ideXlab platform.
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an immersed Boundary lattice boltzmann method for the simulation of the flow past an impulsively started cylinder
Journal of Computational Physics, 2008Co-Authors: Alexandre Dupuis, Philippe Chatelain, Petros KoumoutsakosAbstract:We present a lattice-Boltzmann method coupled with an immersed Boundary technique for the simulation of bluff body flows. The lattice-Boltzmann method for the modeling of the Navier-Stokes equations, is enhanced by a forcing term to account for the No-Slip Boundary Condition on a non-grid conforming Boundary. We investigate two alternatives of coupling the Boundary forcing term with the grid nodes, namely the direct and the interpolated forcing techniques. The present LB-IB methods are validated in simulations of the incompressible flow past an impulsively started cylinder at low and moderate Reynolds numbers. We present diagnostics such as the near wall vorticity field and the drag coefficient and comparisons with previous computational and experimental works and assess the advantages and drawbacks of the two techniques.
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high resolution simulations of the flow around an impulsively started cylinder using vortex methods
Journal of Fluid Mechanics, 1995Co-Authors: Petros Koumoutsakos, Anthony LeonardAbstract:The development of a two-dimensional viscous incompressible flow generated from a circular cylinder impulsively started into rectilinear motion is studied computationally. An adaptative numerical scheme, based on vortex methods, is used to integrate the vorticity/velocity formulation of the Navier–Stokes equations for a wide range of Reynolds numbers (Re = 40 to 9500). A novel technique is implemented to resolve diffusion effects and enforce the No-Slip Boundary Condition. The Biot–Savart law is employed to compute the velocities, thus eliminating the need for imposing the far-field Boundary Conditions. An efficient fast summation algorithm was implemented that allows a large number of computational elements, thus producing unprecedented high-resolution simulations. Results are compared to those from other theoretical, experimental and computational works and the relation between the unsteady vorticity field and the forces experienced by the body is discussed.