In nature and engineering applications, wall-bounded flow often encounter a heterogeneous surface condition, such as the atmosphere boundary layer at urban over riveted aircraft surfaces. particular scenario, when heterogeneity is predominantly in spanwise direction of flow, this roughness can generate secondary cross plane which very different from smooth-wall or homogeneous rough-wall layers.

Pulsatile motion of blood in a circular tube of varying cross-section has been developed by considering slip flow at the tube wall and the blood to be a non- Newtonian biviscous incompressible fluid. The tube wall is supposed to be permeable and the fluid exchange across the wall is accounted for by prescribing the normal velocity of the fluid at the tube wall. The tangential velocity of the fl...

Whereas streamwise effective slope ( $ES_{x}$ ) is accepted as a key topographical parameter in the context of rough-wall turbulent flows, significance its spanwise counterpart $ES_{y}$ remains largely unexplored. Here, response channel flow over irregular, three-dimensional rough walls with systematically varied values studied using direct numerical simulation. All simulations were performed a...

A reduced-order linear feedback controller is designed and applied to turbulent channel flow for drag reduction. From the linearized two-dimensional Navier–Stokes equations a distributed feedback controller, which produces blowing/suction at the wall based on the measured turbulent streamwise wall-shear stress, is derived using model reduction techniques and linearquadratic-Gaussian/loop-transf...

Following the findings in \cite{wangsawijaya2020}, we re-examine turbulent boundary layers developing over surfaces with spanwise heterogeneous roughness of various wavelengths $0.32 \leq S/\overline{\delta} 3.63$, where $S$ is width strips and $\overline{\delta}$ spanwise-averaged boundary-layer thickness. The cases induce counter-rotating secondary flows, these are compared to large-scale str...

QUESTION What is the relationship between vibration of the chest wall and the resulting chest wall force, chest wall circumference,intrapleural pressure, and expiratory flow rate? Is the change in intrapleural pressure during vibration the sum of the intrapleural pressure due to recoil of the lung, chest wall compression, and chest wall oscillation? DESIGN Randomised, within-subject,experimen...

A commonplace view of pressure-driven turbulence in pipes and channels is as “cascades” of streamwise momentum toward the viscous layer at the wall. We present in this paper an alternative picture of these flows as “inverse cascades” of spanwise vorticity, in the cross-stream direction but away from the viscous sublayer. We show that there is a constant spatial flux of spanwise vorticity, due t...