The spatial growth of small perturbations developing on a fully developed base flow in a duct with two inhomogeneous cross-flow directions is examined. For a laminar mean flow it is shown that optimally configured vortices at an upstream cross-section induce large transient amplification of a disturbance energy norm downstream. Such a linear growth is a likely initial stage of transition in duc...

This paper investigates the flow characteristics along a ribbed square duct using time-resolved particle image velocimetry. The Reynolds number, defined by main velocity (1.82 m/s) and hydraulic diameter (80 mm), is 10 000. rotation numbers are 0, 0.13, 0.26, 0.39, 0.52. blockage aspect ratios of 0.1 1, respectively. As number increases, recirculation zone on suction side becomes larger, reatta...

Introduction: Surface roughness can increase the retention of castings by ridges and grooves that are microretentive. This study compared the retention of implant-supported crowns when used with 3 different surface roughness abutments and one temporary cement. Methods: Thirty solid abutments (ITI), 4 mm high, were divided into three groups randomly. In the first group, 10 abutments were roughen...