Effects of second-order slip and drag reduction in boundary layer flows

Wall Slip and Boundary Effects in Polymer Shear Flows

Polymer – surface interactions strongly influence many important industrial and rheological flows. In particular, polymer melts and solutions slip against the surface; this has long been associated with sharkskin and spurt in extrusion, and recent experimental observations suggest that slip also plays a role in the formation of enhanced concentration fluctuations in entangled polymer solutions....

Bubbly turbulent drag reduction is a boundary layer effect.

In turbulent Taylor-Couette flow, the injection of bubbles reduces the overall drag. On the other hand, rough walls enhance the overall drag. In this work, we inject bubbles into turbulent Taylor-Couette flow with rough walls (with a Reynolds number up to 4 x 10(5), finding an enhancement of the dimensionless drag as compared to the case without bubbles. The dimensional drag is unchanged. As in...

Roughness induced boundary slip in microchannel flows.

Surface roughness becomes relevant if typical length scales of the system are comparable to the variations as it is the case in microfluidic setups. Here, an apparent slip is often detected which can have its origin in the misleading assumption of perfectly smooth boundaries. We investigate the problem by means of lattice Boltzmann simulations and introduce an "effective no-slip plane" at an in...

the effects of collaborative strategic reading and direct instruction in persuasion on iranian second grade of high school students persuasive writing and attitudes

this study examined the effects of collaborative strategic reading and direct instruction in persuasion on iranian high school students persuasive writing and attitudes. students in three intact classes were assigned to one of three treatment conditions: collaborative strategic reading and direct instruction in persuasion or direct instruction in persuasion or a control group. treatment effects...

Asymptotic analysis of second-order boundary layer correctors