Inhomogeneous rough surfaces in which strips of roughness alternate with smooth-wall are known to generate large-scale secondary motions. Those motions strongest if the strip width is order half-channel height and they a spatial wall shear stress distribution whose mean value can significantly exceed area-averaged homogeneously smooth surface. In present paper it shown that parametric forcing a...

Arterial stenosis is a problem of immediate significance, as cardiovascular disease the number one leading cause death worldwide. Generally, study stenotic flow assumes smooth, curved and artery. However, real situation unlikely to present an infinitely smooth-surfaced arterial stenosis. Here, impact surface roughness on in was studied via computational fluid dynamics analysis. A patient-specif...

Convective heat transfer of laminar, single-phase flow in rough microtubes is studied. Wall roughness and slope are assumed to possess Gaussian, isotropic distributions. Fractal concepts are used to model the rough microtube. It is shown that due to the existence of wall roughness, both cross-sectional and inside surface areas are increased. A new concept is defined as a figure of merit for ass...

A new general reflectance model for computer graphics is presented.The model is based on physical optics and describes specular, di-rectional diffuse, and uniform diffuse reflection by a surface. Thereflected light pattern depends on wavelength, incidence angle, twosurface roughness parameters. and surface refractive index. The for-mulation is self consistent in terms of...

We study the adhesion between smooth polydimethylsiloxane (PDMS) rubber balls and smooth and rough poly(methyl methacrylate) (PMMA) surfaces, and between smooth silicon nitride balls and smooth PDMS surfaces. From the measured viscoelastic modulus of the PDMS rubber we calculate the viscoelastic contribution to the crack-opening propagation energy γeff(v,T) for a wide range of crack tip velocit...

The influence of grain angularity on the properties of dense flows down a rough inclined plane are investigated. Three-dimensional numerical simulations using the nonsmooth contact dynamics method are carried out with both spherical (rounded) and polyhedral (angular) grain assemblies. Both sphere and polyhedra assemblies abide by the flow start and stop laws, although much higher tilt angle val...

BACKGROUND An important constituent of an orthodontic appliance is orthodontic brackets. It is either the bracket or the archwire that slides through the bracket slot, during sliding mechanics. Overcoming the friction between the two surfaces demands an important consideration in an appliance design. The present study investigated the surface roughness of four different commercially available s...

Appropriate surface wettability and roughness of biomaterials is an important factor in cell attachment and proliferation. In this study, we investigated the correlation between surface wettability and roughness, and biological response in human adipose-derived stem cells (hADSCs). We prepared wettable and rough gradient polyethylene (PE) surfaces by increasing the power of a radio frequency co...

Size bidisperse granular materials in a spherical tumbler segregate into two different patterns of three bands with either small particles at the equator and large particles at the poles or vice versa, depending upon the fill level in the tumbler. Here we use discrete element method simulations with supporting qualitative experiments to explore the effect of the tumbler wall roughness on the se...

Implicit surface techniques provide useful tools for modeling and rendering smooth surfaces. Deriving implicit formulations for fractal representations extends the scope of implicit surface techniques to rough surfaces. Linear fractals modeled by recurrent iterated function systems may be defined implicitly using either geometric distance or escape time. Random fractals modeled using Perlin’s n...