In this paper a previously developed theoretical model of the measurement process performed by a transittime ultrasonic anemometer is applied to a fluid flowing through a circular section pipe. This model considers the influence of the shift of the acoustic pulse trajectory from straight propagation due to the flow on the measured speed. The aim of this work is to estimate the errors induced in...

The lattice Boltzmann method for multi-component immiscible fluids is applied to simulations of the behaviour of a drop in a square pipe flow for various Reynolds numbers of 10<Re<500, Weber numbers of 0<We<250 and viscosity ratios of η=1/5, 1, 2 and 5. It is found that, for low Weber numbers, the drop moves straight along a stable position on the diagonal line of the pipe section, and it moves...

Large-eddy simulations (LES) of turbulent flow in a smoothwall pipe at Reynolds numbers based on the pipe Radius R and wall friction velocity in the range Reτ = 2,000−2,000,000 are discussed. Using a Reynolds number based on D and the bulkflow velocity, then corresponding values are ReD = 91,800 − 165,000,000. For the LES, the spectral-element code SEMTEX was used combined with the stretched-vo...

The flow characteristics of aqueous foams were studied in a thin flow channel and a round pipe instrumented for pressure gradient and flow rate measurements. The quality of the foam was varied by controlling the volumetric flow rate of liquid and gas, and different flow types were identified and charted. Uniform foams move as a rigid body lubricated by water generated by breaking foam at the wa...

Transitional pipe flow is modeled as a one-dimensional excitable and bistable medium. Models are presented in two variables, turbulence intensity and mean shear, that evolve according to established properties of transitional turbulence. A continuous model captures the essence of the puff-slug transition as a change from excitability to bistability. A discrete model, which additionally incorpor...

A new technique for sensing turbulence in single-phase fluid flow by pulsed ultrasound is developed. The velocity component of turbulence perpendicular to the flow axis is sensed by two ultrasonic transducers mounted diametrically opposite on the pipe. The technique facilitates detecting variations in time of flight of two ultrasonic pulses transmitted simultaneously in the opposite directions ...

This paper describes a user-friendly software for the calculation of general piping system networks composed of virtually any parallel and series pipe arrangement. Solution of the network is made with recourse to the iterative method of Hardy Cross. Solution is provided for pressure and flow-rate in each branch. Dimensioning problems, where pump characteristics or a pipe diameter are sought for...

Direct numerical simulation of the weakly turbulent flow of non-Newtonian fluids is undertaken for two different generalised Newtonian rheology models using a spectral element-Fourier method. Results for a power law (shear-thinning) rheology agree well with experimentally determined logarithmic layer correlations and with other previously published experimental work. As the flow index becomes s...

ÐThe unsteady ̄ow of blood in a straight, long, rigid pipe, driven by an oscillatory pressure gradient is studied. Three di€erent non±newtonian models for blood are considered and compared. One of them turns out to o€er the best ®t of experimental data, when the rheological parameters are suitably ®xed. Numerical results are obtained by a spectral collocation method in space and the implicit tr...

We design a Lyapunov based boundary feedback controller for achieving mixing in a D pipe ow governed by Navier Stokes equations We show that the control law maximizes a measure of mixing that incorporates stretching and folding of material elements while at the same time minimi zing the control e ort and the sensing e ort The penalty on sensing results in a static output feedback control law ra...