Enhancing the dynamic range of Ultrasound Imaging Velocimetry using interleaved imaging

In recent years, non-invasive velocity field measurement based on correlation of ultrasound images has been introduced as a promising technique for fundamental research into disease processes, as well as a diagnostic tool. A major drawback of the method is the relatively limited dynamic range when conventional echography equipment is used. We...

Complete removal of ghost particles in Tomographic-PIV

This paper discusses and compares several methods, which aim to remove spurious peaks, i.e. ghost particles, from the volume intensity reconstruction in Tomographic-PIV. The assessment is based on numerical simulations of timeresolved tomographic-PIV experiments in linear shear flows. Within the reconstructed volumes intensity peaks are detected...

Drag reduction by surface treatment in turbulent Taylor-Couette flow

We use a Taylor-Couette facility to study the drag reducing effects of commercial surface products at high shear Reynolds numbers (Res) under perfect couter-rotating conditions (riwi=rowo). The correlation between torque contribution of the von Karman flow and shear Reynolds number is investigated. At this moment no significant drag changes are...

Dispersion of bubbles in fully developed channel flow

Dispersion and preferential concentration of small, low Stokes number bubbles in horizontal turbulent channel flow is studied by DNS and experiments. A DNS of turbulent channel flow at Re = 360 with Lagrangian tracking of one-way coupled bubbles (d < n, St = 1.3×10?3) shows that equilibrium bubble concentration profiles can be described by a...

Particle Entrainment in Spherical-Cap Wakes

In this work we study the preferential concentration of small particles in the turbulent wake behind a spherical-cap object. We present a model predicting the mean particle concentration in the near-wake as a function of the characteristic Stokes number of the problem, the turbulence level and the Froude number. We compare the model with our...

Direct numerical simulation of turbulent pipe flow up to a Reynolds number of 61,000

In this paper we will present results of several direct numerical simulations of turbulent pipe flow. The highest Reynolds number simulated in this study was 61, 000. Our numerical model uses Fourier expansions in axial and circumferential directions and 6th order staggered compact finite difference in the wall normal direction. Apart form...

Flow measurements in transonic flows of organic fluids with a Ludwieg tube type setup (poster)

Long-range ?PIV in the turbulent region of a jet, at high Reynolds numbers

The present work involves the investigation of the fine scale motions in the turbulent region of a high Reynolds number air jet. In the fully developed region of the jets, the small scales of turbulence are assumed to be isotropic, and expected to contain elongated vortices (worms), whose diameter scales with the Kolmogorov length scale. Aimed...