scholarly journals Numerical Study of Surface Roughness Effects on the Behavior of Fluid Flow in Micro-channels

2019 ◽  
Vol 6 (2) ◽  
pp. 285-292
Author(s):  
CharefKhoudja Nabila ◽  
Soudani Azzedine
Keyword(s):  
Surface Roughness ◽  
Fluid Flow ◽  
Numerical Study ◽  
Roughness Effects ◽  
Micro Channels

Investigation of surface roughness effects on fluid flow in passive micromixer

2013 ◽  
Vol 20 (12) ◽  
pp. 2261-2269 ◽  
Author(s):  
Gaurav Pendharkar ◽  
Raghavendra Deshmukh ◽  
Rajendra Patrikar
Keyword(s):  
Surface Roughness ◽  
Fluid Flow ◽  
Roughness Effects ◽  
Passive Micromixer

Effects of Real Surface Roughness on Fluid Flow in Nanochannels

2010 ◽  
Author(s):  
Ali Kharazmi ◽  
Reza Kamali
Keyword(s):  
Molecular Dynamics ◽  
Surface Roughness ◽  
Fluid Flow ◽  
Computer Program ◽  
Md Simulation ◽  
Real Surface ◽  
Micro Channels

In the present study, a computer program based on a molecular dynamics scheme has been developed for simulating fluid flow in nano- and micro-channels with roughness. According to the previous studies of nanochannels flows, surface roughness has a great effect on the rheology of the flow. Therefore a more realistic surface roughness has been developed and its influence on the fluid flow has been investigated using Molecular Dynamics (MD) Simulation.

Molecular Dynamic Simulation of Surface Roughness Effects on Nanoscale Flows

2009 ◽  
Author(s):  
Ali Kharazmi ◽  
Reza Kamali
Keyword(s):  
Surface Roughness ◽  
Solid Wall ◽  
Intermolecular Forces ◽  
Intermolecular Potential ◽  
Roughness Effects ◽  
Time Step ◽  
Restoring Force ◽  
Rapid Sampling ◽  
Micro Channels ◽  
Fifth Order

In the present study, a molecular based scheme has been developed for simulating flows in nano- and micro-channels with roughness. In micro channel flow, there is some difference on the flow friction between roughness and cavitations which is not well studied. The presented approach is based on the molecular dynamics (namely MD) in which different ensemble has been used. For modeling the simulation the classical Newtonian particles are allowed to obey Newtonian mechanics and intermolecular forces are founded by integrating intermolecular potential. Lennard-Jones potential is used to model the interactions between particles. Particles equation of motion is integrated using fifth order Gear predictor-corrector. To ensure rapid sampling of phase space, the time step is made as large as possible. Periodic boundary condition is implemented via minimum image convention. Each atom of the solid wall is anchored at its lattice site by a harmonic restoring force and its temperature has been controlled by utilizing Nose-Hoover thermostat. The roughness is implemented on the lower channel wall. To make a comparison between the effect of roughness and cavitation, the same dimension is used for both for different aspect ratio. To allow comparison with previous results the same fluid density has been used. The effects of surface roughness and cavitation on velocity distribution of hydrophobic and hydrophilic wall undergoing Poiseuille flow are presented.

A Numerical Study of Surface Roughness Effects on Ultra-Thin Gas Films

1986 ◽  
Vol 108 (2) ◽  
pp. 171-177 ◽  
Author(s):  
J. W. White ◽  
P. E. Raad ◽  
A. H. Tabrizi ◽  
S. P. Ketkar ◽  
P. P. Prabhu
Keyword(s):  
Surface Roughness ◽  
Rough Surface ◽  
Reynolds Equation ◽  
Numerical Study ◽  
Surface Film ◽  
Maximum Load ◽  
Roughness Effects ◽  
Number Range ◽  
Pressure Diffusion ◽  
Bearing Number

A wedge bearing with transverse sinusoidal roughness pattern is studied numerically in order to predict the effect of surface roughness on compressible fluid films. A variable grid implicit finite difference scheme is used to provide steady-state solutions of the Reynolds equation over a bearing number range of five orders of magnitude. At a fixed bearing geometry and orientation, the bearing load is found to increase to a maximum as the bearing number increases, then to decrease and asymptotically approach a limiting value as the bearing number increases further. This is quite unlike the behavior of an incompressible fluid bearing. Analysis indicates that the maximum load occurs at a condition where pressure diffusion and Couette effects of the fluid film are of an equal order of magnitude. The increased emphasis of the pressure diffusion physics is due to the short length scales of the rough surfaces which “trigger” the higher derivative diffusion terms in the Reynolds equation. The criterion required for validity of an infinite bearing number solution with a rough surface is found to be much more restrictive than that of a smooth surface bearing. Last, the type of rough surface film clearance averages used in incompressible lubrication are shown to be incorrect for analysis of very thin gas films. It would appear that one application of this information would be the design of an artificially roughened surface for the take-off and landing of magnetic head sliders so as to minimize contact and wear of the magnetic media.

NUMERICAL STUDY ON THE INFLUENCE OF SURFACE ROUGHNESS ON FLUID FLOW AND MASS TRANSFER IN A FLAT-PLATE MICROCHANNEL BIOREACTOR

2007 ◽  
Vol 18 (02) ◽  
pp. 131-155 ◽  
Author(s):  
YAN ZENG ◽  
THONG-SEE LEE ◽  
PENG YU ◽  
HONG-TONG LOW
Keyword(s):  
Mass Transfer ◽  
Surface Roughness ◽  
Shear Stress ◽  
Fluid Flow ◽  
Cell Growth ◽  
Flat Plate ◽  
Numerical Study ◽  
Maximum Shear Stress ◽  
Critical Conditions ◽  
Minimum Concentration

Surface roughness exists in most microfluidic devices due to the microfabrication technique or particle adhesion. The present study has developed a numerical model based on Finite Volume Method to simulate the fluid flow and mass transfer in a flat-plate microchannel bioreactor with an array of rough elements uniformly placed on the bottom wall. Both semicircle and triangle roughness are considered to include more shapes of roughness elements. A monolayer of cells is assumed to attach to the base of the channels and consumes species from culture medium. The results show that the roughness size ratio (α) and the roughness distribution ratio (β) have direct and significant effects on fluid flow and mass transfer. The dimensionless parameters Peclet number (Pe) and Damkohler number (Da) can also influence mass transfer greatly. Although the two types of roughness have similar effects, at the same condition, the triangle roughness has larger effect on shear stress by showing higher dimensionless values at the channel base; the semicircle roughness has larger effect on mass transfer by showing lower dimensionless minimum base concentration [Formula: see text] and higher dimensionless absorption rate (Δj%). However, it is important to ensure the lower maximum shear stress and the adequate minimum species concentration for cell growth in rough channels. Hence, if the maximum shear stress and minimum concentration in rough channels can satisfy the critical conditions for cell growth, rough channels would be better than smooth channels because of their lower shear stress at the flat-bed part and higher mass transfer efficiency. The results would provide guidance on the flow and perfusion requirements to avoid shear stress damage and solute depletion or toxicity during cell culture.

Fluid Flow Bifurcation in Micro-Channels

2003 ◽  
Author(s):  
S. Patel ◽  
D. Drikakis
Keyword(s):  
Fluid Flow ◽  
Numerical Study ◽  
Reynolds Numbers ◽  
Flow Transition ◽  
Incompressible Fluid Flow ◽  
Low Reynolds Numbers ◽  
Multigrid Algorithm ◽  
Micro Channels ◽  
Micro Flows ◽  
Flow Through

The paper presents a numerical study of incompressible fluid flow through micro-channels. Using a high-resolution numerical method (second-order accurate) in conjunction with a non-linear multigrid algorithm and the pseudo-compressibility approach, we have investigated micro-flows through straight channels, as well as through a sudden contraction-expansion geometry. For the straight channel geometry, the computational results are in reasonable agreement with the experimental data for various low Reynolds numbers. For the contraction-expansion geometry, the results reveal the flow transition to instability. This is manifested in the form of asymmetric separation downstream of the expansion.

Effects of Surface Roughness on Flows Through Nano/Micro Channel Based Biomedical Devices: A Study by Lattice Boltzmann Method

2007 ◽  
Author(s):  
Mohammed S. Mayeed ◽  
Golam M. Newaz
Keyword(s):  
Surface Roughness ◽  
Boundary Conditions ◽  
Lattice Boltzmann ◽  
Rough Boundary ◽  
Biomedical Devices ◽  
Roughness Effects ◽  
Average Roughness ◽  
Flow Profiles ◽  
Micro Channels ◽  
Boltzmann Method

The objective of this research is to study the effects of surface roughness on flows through nano/micro channels with a focus on designing better biomedical devices. A two dimensional computational model for fluid flow based on Lattice Boltzmann (LB) method has been applied first to a 10 μm width channel with flat boundary conditions and the flow profiles have been found to have an excellent comparison with analytical results. Rough boundary conditions using rectangular tooth-shaped corrugations giving about 0.25 μm average roughness have then been applied to the same 10 μm channel flow. We have observed significant differences in the velocity profiles between the flows with rough and flat boundary conditions. Boundary slips have also been observed in case of flows with rough boundary conditions. Surface roughness effects have increased or the differences between the flows with rough and flat boundary conditions have increased with decreased channel widths.

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