Fully developed turbulent pipe flow: a comparison between direct numerical simulation and experiment

Abstract

Direct numerical simulations (DNS) and experiments are carried out to study fully developed turbulent pipe flow at Reynolds number Rec ≈ 7000 based on centreline velocity and pipe diameter. The agreement between numerical and experimental results is excellent for the lower-order statistics (mean flow and turbulence intensities) and reasonably good for the higher-order statistics (skewness and flatness factors). To investigate the differences between fully developed turbulent flow in an axisymmetric pipe and a plane channel geometry, the present DNS results are compared to those obtained from a channel flow simulation. Beside the mean flow properties and turbulence statistics up to fourth order, the energy budgets of the Reynolds-stress components are computed and compared. The present results show that the mean velocity profile in the pipe fails to conform to the accepted law of the wall, in contrast to the channel flow. This confirms earlier observations reported in the literature. The statistics on fluctuating velocities, including the energy budgets of the Reynolds stresses, appear to be less affected by the axisymmetric pipe geometry. Only the skewness factor of the normal-to-the-wall velocity fluctuations differs in the pipe flow compared to the channel flow. The energy budgets illustrate that the normal-to-the-wall velocity fluctuations in the pipe are altered owing to a different ‘impingement’ or ‘splatting’ mechanism close to the curved wall.

Influence of Stokes number on the velocity and concentration distributions in particle-laden jets

“…The strong negative values close to the wall are due to the damping of turbulent fluctuations by the wall, which are under-estimated by the values of G * , because the measurement plane is downstream from the exit plane where fluctuations at the jet edge are greater than that close to the wall within the pipe. Nevertheless, this measurement of a high magnitude, negative G * in a thin, near-wall region, followed by a low magnitude, positive gradient G * just outside of this near-wall region, is also consistent with previous single-phase measurements of turbulent pipe and channel flows (Eggels et al 1994;Kim et al 1987;Sommerfeld 2002). Therefore, in the near-wall region of the pipe at low Stokes numbers, turbophoresis is deduced to exert a significant force towards the wall, causing particles to migrate towards the pipe boundary (as illustrated in figure 8b).…”

Helicity fluctuations and turbulent energy production in rotating and non-rotating pipes

“…Orlandi & Fatica (1995) have shown that the second and higher order statistics of the velocity field for the non-rotating pipe agreed with those obtained in other simulations (Eggels et al (1994)) as well as in experiments at the same low Reynolds number.…”

Turbulent structure of high-amplitude pressure peaks within the turbulent boundary layer

“…This intermittent behaviour is also evident in the high values of kurtosis factor (k) in the near-wall velocity fluctuation and the wall shear stress (τ w ). The DNS of Kim et al (1987) and Eggels et al (1994) show intermittency of streamwise velocity in the immediate vicinity of the wall with kurtosis factor of k 4 and 5.3, respectively. Alfredsson et al (1988b) also measured k = 5-6.5 for the streamwise velocity at y + = 1 within at a wide range of Reynolds numbers in different flow facilities.…”