Boundary Layer Mixture Model for a Microbubble Drag Reduction Technique

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...

Drag reduction in a flat-plate turbulent boundary layer flow by polymer additives

This paper presents a theoretical study on the velocity distribution and the friction factor of boundary layer flows with polymer additives starting from the concept of “stress deficit.” A novel method of order of magnitude analysis is developed, which converts the governing equations of boundary layer flow into a solvable ordinary differential equation, thus the total shear stress distribution...

URANS Study of Air-Layer Drag Reduction in a High- Reynolds-Number Flat-Plate Turbulent Boundary Layer

The air layer formation in a high Reynolds-number flat plate turbulent boundary layer is simulated using a two-phase sharp interface Cartesian grid solver. The interface is tracked by a coupled level set and volume-of-fluid method (CLSVOF) and turbulence is modeled by a Spalart-Allmaras (SA) turbulence model with a wall function (WF) approach. The air layer along the entire test plate is succes...

A hybrid method for singularly perturbed delay boundary value problems exhibiting a right boundary layer

The aim of this paper is to present a numerical method for singularly perturbed convection-diffusion problems with a delay. The method is a combination of the asymptotic expansion technique and the reproducing kernel method (RKM). First an asymptotic expansion for the solution of the given singularly perturbed delayed boundary value problem is constructed. Then the reduced regular delayed diffe...

A mixture model for dimension reduction