There is much current interest in modelling suspensions of algae and other microorganisms for biotechnological exploitation, and many bioreactors are of tubular design. Using generalized Taylor dispersion theory, we develop a population-level swimming-advection-diffusion model for suspensions of micro-organisms in a vertical pipe flow. In particular, a combination of gravitational and viscous t...

Auto-Pipe is a tool that aids in the design, evaluation and implementation of pipelined applications that are distributed across a set of heterogeneous devices including multiple processors and FPGAs. It has been developed to meet the needs arising in the domains of communications, computation on large datasets, and real time streaming data applications. In this paper, the AutoPipe design flow ...

Dams created by American beavers (Castor canadensis) are associated with positive and negative values, and beaver management decisions are based on stakeholder perception and levels of tolerance. Lethal trapping is a widely used and accepted tool to reduce beaver damage caused by flooding; however, acceptable and efficacious non-lethal tools are increasingly desired by the public.We traced the ...

Turbulent scalar mixing in the near field of a tee mixer (transverse jet in a pipe) is studied using Particle Image Velocimetry (PIV) and Planar Laser Induced Fluorescence (PLIF). Two jet-to-pipe velocity ratios, r = 3.06 and r = 5.04, are investigated for a turbulent pipe flow at a Reynolds number of 20,850. The laser measurement techniques are described, typical flow structures in the near fi...

The effect of streamwise-varying steady transpiration on turbulent pipe flow is examined using direct numerical simulation at fixed friction Reynolds number Reτ = 314. The streamwise momentum equation reveals three physical mechanisms caused by transpiration acting in the flow: modification of Reynolds shear stress, steady streaming and generation of non-zero mean streamwise gradients. The infl...

Both the inherent intractability and complex beauty of turbulence reside in its large range of physical and temporal scales. This range of scales is captured by the Reynolds number, which in nature and in many engineering applications can be as large as 10(5)-10(6). Here, we report turbulence measurements over an unprecedented range of Reynolds numbers using a unique combination of a high-press...

Direct numerical simulation of transitional pipe flow is carried out in a long computational domain in order to characterize the dynamics within the saddle region of phase space that separates laminar flow from turbulent intermittency. For Reynolds numbers ranging from Re=1800 to 2800, a shoot and bisection method is used to compute critical trajectories. The chaotic saddle or edge state approa...

We propose a two-phase model having a Newtonian rheology for the fluid phase and friction for the particle phase to describe bed-load transport in laminar pipe flows. This model is able to provide a description of the flow of the mobile granular layer. When the flow is not significantly perturbed, simple analytical results of the particle flux varying cubically with the Shields number can be ob...

Several experimental and numerical studies have shown that turbulent motions in circular pipe flow near transitional Reynolds numbers may not persist forever, but may decay. We study the properties of these decaying states within direct numerical simulations for Reynolds numbers up to 2200 and in pipes with lengths equal to 5, 9, and 15 times the diameter. We show that the choice of the ensembl...