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.

ON BOUNDARY CONDITIONS IN THE FINITE VOLUME LATTICE BOLTZMANN METHOD ON UNSTRUCTURED MESHES

1999 ◽  
Vol 10 (06) ◽  
pp. 1003-1016 ◽  
Author(s):  
GONGWEN PENG ◽  
HAOWEN XI ◽  
SO-HSIANG CHOU
Keyword(s):  
Shear Flow ◽  
Boundary Conditions ◽  
Numerical Simulations ◽  
Lattice Boltzmann Method ◽  
Finite Volume ◽  
Simple Shear ◽  
Lattice Boltzmann ◽  
Unstructured Meshes ◽  
Simple Shear Flow ◽  
Boltzmann Method

Boundary conditions in a recently-proposed finite volume lattice Boltzmann method are discussed. Numerical simulations for simple shear flow indicate that the extrapolation and the half-covolume techniques for the boundary conditions are workable in conjunction with the finite volume lattice Boltzmann method for arbitrary meshes.

Characterization and Laboratory Simulation of Turbine Airfoil Surface Roughness and Associated Heat Transfer

1998 ◽  
Vol 120 (2) ◽  
pp. 337-342 ◽  
Author(s):  
D. G. Bogard ◽  
D. L. Schmidt ◽  
M. Tabbita
Keyword(s):  
Heat Transfer ◽  
Surface Roughness ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Free Stream ◽  
Laboratory Simulation ◽  
Roughness Effects ◽  
Average Roughness ◽  
Airfoil Surface ◽  
Free Stream Turbulence

The physical characteristics of surface roughness observed on first-stage high-pressure turbine vanes that had been in service for a long period were investigated in this study. Profilometry measurements were utilized to provide details of the surface roughness formed by deposits of foreign materials on different parts of the turbine vane. Typical measures of surface roughness such as centerline average roughness values were shown to be inadequate for characterizing roughness effects. Using a roughness shape parameter originally derived from regular roughness arrays, the turbine airfoil roughness was characterized in terms of equivalent sand-grain roughness in order to develop an appropriate simulation of the surface for laboratory experiments. Two rough surface test plates were designed and fabricated. These test plates were evaluated experimentally to quantify the heat transfer rate for flow conditions similar to that which occurs on the turbine airfoil. Although the roughness levels on the two test plates were different by a factor of two, both surfaces caused similar 50 percent increases in heat transfer rates relative to a smooth surface. The effects of high free-stream turbulence, with turbulence levels from 10 to 17 percent, were also investigated. Combined free-stream turbulence and surface roughness effects were found to be additive, resulting in as much as a 100 percent increase in heat transfer rate.

ROUGHNESS EFFECT OF DIFFERENT GEOMETRIES ON MICRO GAS FLOWS BY LATTICE BOLTZMANN SIMULATION

2009 ◽  
Vol 20 (06) ◽  
pp. 953-966 ◽  
Author(s):  
CHAOFENG LIU ◽  
YUSHAN NI ◽  
YONG RAO
Keyword(s):  
Surface Roughness ◽  
Lattice Boltzmann ◽  
Experimental Studies ◽  
Resistance Coefficient ◽  
Lattice Boltzmann Model ◽  
Gas Flows ◽  
Fractal Boundary ◽  
Roughness Effects ◽  
Roughness Effect ◽  
Relative Roughness

The roughness effects of the gas flows of nitrogen and helium in microchannels with various relative roughnesses and different geometries are studied and analyzed by a lattice Boltzmann model. The shape of surface roughness is simulated to be square, sinusoidal, triangular, and fractal. Numerical computations compared with theoretical and experimental studies show that the roughness geometry is an important factor besides the relative roughness in the study of the effects of surface roughness. The fractal boundary presents a higher influence on the velocity field and the resistance coefficient than other regular boundaries at the same Knudsen number and relative roughness. In addition, the effects of rarefaction, compressibility, and roughness are strongly coupled, and the roughness effect should not be ignored in studying rarefaction and compressibility of the microchannel as the relative roughness increases.

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