Boundary Drag Force Acting on an Impenetrable Nano-Particle

2010 ◽  
Author(s):  
H. Karrabi ◽  
M. H. Kebriai ◽  
M. R. Meigounpoury
Keyword(s):  
Fundamental Problem ◽  
Aqueous Media ◽  
Slip Boundary Condition ◽  
Reynolds Numbers ◽  
Nano Particles ◽  
Nano Particle ◽  
Coating Materials ◽  
Technical Problems ◽  
Slip Boundary ◽  
Automotive Engines

Flow over nano spheres is a fundamental problem encountered in many engineering technical problems and the motion of nano-particles is important in many technical areas, for example nano-organizms motion in aqueous media, super hydrophobic spray for coating materials, nano-capsules for detecting cancer, and additive nano-particles in oil and fuel for automotive engines. In this paper computations are performed to determine the steady flow forces acting on the stationary nano-tube for Reynolds numbers in the range of 0.1<Re<40 and 0.01<Kn<0.1 with the slip boundary condition. A single dimensionless parameter, the so-called slip number (Tr), is defined to account for the slip at the nano-particle boundary., Increasing slip causes to delay of flow separation around the nano-tube surface. Numerical results confirm that slip variations can not affect on the drag coefficient values at low Reynolds regime. At higher Reynolds number increasing slip causes to drag reduction of flow around the Nano-Tube.

Numerical Analysis of the Drag Forces Acting on the Stationary Impenetrable Nano-Tube

2008 ◽  
Author(s):  
M. R. Meigounpoory ◽  
A. Rahi ◽  
A. Mirbozorgi
Keyword(s):  
Boundary Condition ◽  
Dimensionless Parameter ◽  
Slip Boundary Condition ◽  
Reynolds Numbers ◽  
Nano Particles ◽  
Tube Surface ◽  
Coating Materials ◽  
Slip Boundary ◽  
Automotive Engines ◽  
Drag Forces

The motion of nano-particles is important in many technical areas, for example super hydrophobic spray for coating materials, nano-capsules for detecting cancer, and additive nano-particles in oil and fuel for automotive engines. In this paper computations are performed to determine the steady flow forces acting on the stationary nano-tube for Reynolds numbers in the range of 0.1<Re<40 and 0.01<Kn<0.1 with the slip boundary condition. A single dimensionless parameter, the so-called slip number (Tr), is defined to account for the slip at the cylinder’s boundary. Increasing slip causes to delay of flow separation around the nano-tube surface. Numerical results confirm that slip variations can not affect on the drag coefficient values at low Reynolds regime. At higher Reynolds number increasing slip causes to drag reduction of flow around the nano tube.

Numerical Investigation of the Drag and Lift Forces Acting on Impenetrable Rotating Spherical Nano-Particle

2008 ◽  
Author(s):  
M. R. Meigounpoory ◽  
A. Rahi ◽  
A. Mirbozorgi
Keyword(s):  
Lift Coefficient ◽  
Three Dimensional ◽  
Slip Boundary Condition ◽  
Slip Condition ◽  
Nano Particle ◽  
Slip Coefficient ◽  
Slip Boundary ◽  
Lift Forces ◽  
Drag And Lift ◽  
Drag And Lift Coefficient

The drag and lift forces acting on a rotating impenetrable spherical suspended nano-particle in a homogeneous uniform flow are numerically studied by means of a three-dimensional numerical simulation with slip boundary condition. The effects of both the slip coefficient and rotational speed of the nanosphere on the drag and lift forces are investigated for Reynolds numbers in the range of 0.1 < Re < 100. Increase of rotation increases the drag and lift force exerted by flow at the surface of nano-sphere. By increasing slip coefficient the values of drag and lift coefficients decreases. At full slip condition, rotation of the nano-sphere has not significant effects on the drag and lift coefficient values moreover the lift coefficient of flow around the rotating spherical particle will be vanished. Present numerical results at no-slip condition are in good agreements with certain results of flow around of rotating sphere.

scholarly journals Simulation of Fluid and Structure Interface with Immersed Boundary–Lattice Boltzmann Method Involving Turbulence Models

2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
Zhikai Wang ◽  
Xiongliang Yao ◽  
Nana Yang ◽  
Zhenhuan Xu
Keyword(s):  
Coordinate System ◽  
Turbulent Flows ◽  
Lattice Boltzmann ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Slip Boundary Condition ◽  
Reynolds Numbers ◽  
Immersed Boundary ◽  
Square Cylinder ◽  
Slip Boundary

The multiple-relaxation-time (MRT) version of the immersed boundary–lattice Boltzmann (IB-LB) method is developed to simulate fluid-structure interfaces. The innovations include the implicit velocity correction to ensure no-slip boundary conditions and the incorporated Smagorinsky’s algebraic eddy viscosity for simulating turbulent flows. Both straight and curved interfaces are investigated. The streamlines penetration can be well prevented, which means the no-slip boundary condition can be guaranteed. Due to the existence of two coordinate systems: the Lagrangian coordinate system and the Eulerian coordinate system, the velocity and force properties on the structure can be easily calculated. Several benchmark simulation cases are carried out to verify the correctness of the model, including flow around circular cylinder at Re = 20, 150, and 3900 and flow around square cylinder at Re = 150 and 1000. The results agree well with previous studies, especially in the events of lower Reynolds numbers. Due to the three-dimensional turbulence vortex effects, the discrepancy increases are associated with higher Reynolds numbers. In addition, the effect of rotating velocity on the interaction process of the square cylinder in flows is researched, coupled with the capability of dealing with the moving boundaries.

Influence of slip on the dynamics of two-dimensional wakes

2009 ◽  
Vol 633 ◽  
pp. 437-447 ◽  
Author(s):  
DOMINIQUE LEGENDRE ◽  
ERIC LAUGA ◽  
JACQUES MAGNAUDET
Keyword(s):  
Slip Boundary Condition ◽  
Reynolds Numbers ◽  
Transitional Flow ◽  
Two Dimensional ◽  
Slip Boundary ◽  
Two Dimensional Flow ◽  
Wake Instability ◽  
Shedding Frequency ◽  
Axisymmetric Bodies ◽  
Effective Friction

We study numerically the two-dimensional flow past a circular cylinder as a prototypical transitional flow, and investigate the influence of a generic slip boundary condition on the wake dynamics. We show that slip significantly delays the onset of recirculation and shedding in the wake behind the cylinder. As expected, the drag on the cylinder decreases with slip, with an increased drag sensitivity for large Reynolds numbers. We also show that past the critical shedding Reynolds number, slip decreases the vorticity intensity in the wake, as well as the lift forces on the cylinder, but increases the shedding frequency. We further provide evidence that the shedding transition can be interpreted as a critical accumulation of surface vorticity, similarly to related studies on wake instability of axisymmetric bodies. Finally, we propose that our results could be used as a passive method to infer the effective friction properties of slipping surfaces.

scholarly journals The appearance of boundary layers and drift flows due to high-frequency surface waves

2012 ◽  
Vol 707 ◽  
pp. 482-495 ◽  
Author(s):  
Ofer Manor ◽  
Leslie Y. Yeo ◽  
James R. Friend
Keyword(s):  
Boundary Layer ◽  
Surface Waves ◽  
High Frequency ◽  
Slip Boundary Condition ◽  
Inertial Effects ◽  
Velocity Amplitude ◽  
Slip Boundary ◽  
Long Period ◽  
Bulk Waves ◽  
Schlichting Streaming

AbstractThe classical Schlichting boundary layer theory is extended to account for the excitation of generalized surface waves in the frequency and velocity amplitude range commonly used in microfluidic applications, including Rayleigh and Sezawa surface waves and Lamb, flexural and surface-skimming bulk waves. These waves possess longitudinal and transverse displacements of similar magnitude along the boundary, often spatiotemporally out of phase, giving rise to a periodic flow shown to consist of a superposition of classical Schlichting streaming and uniaxial flow that have no net influence on the flow over a long period of time. Correcting the velocity field for weak but significant inertial effects results in a non-vanishing steady component, a drift flow, itself sensitive to both the amplitude and phase (prograde or retrograde) of the surface acoustic wave propagating along the boundary. We validate the proposed theory with experimental observations of colloidal pattern assembly in microchannels filled with dilute particle suspensions to show the complexity of the boundary layer, and suggest an asymptotic slip boundary condition for bulk flow in microfluidic applications that are actuated by surface waves.

Numerical Simulation for Microconvection Around Nano-Particle With Brownian Motion in Liquid

2003 ◽  
Author(s):  
B. X. Wang ◽  
H. Li ◽  
X. F. Peng ◽  
L. X. Yang
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Brownian Motion ◽  
Numerical Model ◽  
Temperature Gradient ◽  
Transfer Process ◽  
Heat Transfer Process ◽  
Nano Particles ◽  
Analytic Method ◽  
Nano Particle

The development of a numerical model for analyzing the effect of the nano-particles’ Brownian motion on the heat transfer is described. By using the Maxwell velocity distribution relations to calculate the most possible velocity of fluid molecules at certain temperature gradient location around the nano-particle, the interaction between fluid molecules and one single nano-particle is analyzed and calculated. Based on this, a syntonic system is proposed and the coupled effect that Brownian motion of nano-particles has on fluid molecules is simulated. This is used to formulate a reasonable analytic method, facilitating laboratory study. The results provide the essential features of the heat transfer process, contributed by micro-convection to be considered.

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