|
| |
|
| |
|
|
Dynamics of secondary flow in rectangular channel
Uruba, Václav ; Hladík, Ondřej ; Jonáš, Pavel
Secondary flow in straight channel of rectangular cross-section is studied experimentally. Special attention is devoted to dynamics of secondary vortices in channel corner. The stereo time-resolved PIV method is used to acquire time series of the 3-component vector fields in plane perpendicular to the channel axis. The dynamics of the vortical structures is studied using Proper Orthogonal Decomposition method giving the energetic modes.
|
|
|
Approximation of velocity distribution in open channel flow
Ivanova, Irina ; Vlasák, Pavel ; Chára, Zdeněk ; Kysela, Bohuš
The paper deals with approximation of spatial distribution of mean downstream velocity of sub-critical turbulent flow in an open rectangular channel with rough bed. New formulae of the local downstream velocity component Vx(y, z) dependence on the vertical coordinate y and lateral coordinate z were introduced. The vertical velocity profile was approximated by log-law and the power law was used to describe the effect of channel walls on the horizontal velocity profile. The suggested formulae of spatial downstream velocity component distribution were calibrated and verified using the experimental data obtained by PIV method. The proposed approximation is in good agreement with experimental data, the difference between experimental and calculated data is in range of 5 - 10% except the area near the channel’s corners and water level, where the maximal difference reaches 60% and 30% of experimental values, respectively.
|
|
|
Střihové napětí na stěně pod velkou bublinou stoupající v nakloněném plochém kanále
Tihon, Jaroslav ; Pěnkavová, Věra ; Vejražka, Jiří
The motion of single air bubbles in an inclined flat water channel is investigated experimentally. The electrodiffusion technique of near-wall flow diagnostics is applied to measure the wall shear stress distribution under large bubbles rising along the upper channel wall. The electrodiffusion measurements are synchronized with the visual observation of bubble movement done by a high-speed camera. The analysis of video records provides information on the bubble shape and terminal velocity. The experiments are carried out for three different channel heights and cover a wide range of channel inclination angles (from horizontal to vertical position). The experimental results on bubble motion characteristics obtained in stagnant and upward-flowing liquid arrangements are confronted with the recent predictions and scaling provided by theoretical models.
|
|
| |
|
| |
|
| |
|
| |
|
| |
guest ::
