scholarly journals Experimental study of temperature fluctuations in forced stably stratified turbulent flows

2013 ◽  
Vol 25 (1) ◽  
pp. 015111 ◽  
Author(s):  
A. Eidelman ◽  
T. Elperin ◽  
I. Gluzman ◽  
N. Kleeorin ◽  
I. Rogachevskii
Keyword(s):  
Experimental Study ◽  
Turbulent Flows ◽  
Temperature Fluctuations

Highly turbulent Couette–Taylor bubbly flow patterns

2000 ◽  
Vol 422 ◽  
pp. 55-68 ◽  
Author(s):  
K. ATKHEN ◽  
J. FONTAINE ◽  
J. E. WESFREID
Keyword(s):  
Experimental Study ◽  
Free Surface ◽  
Turbulent Flows ◽  
Rotational Speed ◽  
Bubbly Flow ◽  
Axial Flow ◽  
Taylor Vortices ◽  
Phase Velocities ◽  
Temporal Properties ◽  
Visualization Techniques

We present the results of experimental study of a Couette–Taylor system with superimposed axial flow and an upper free surface, in the high Taylor number regime. At large Taylor numbers, when the rotational speed of the inner cylinder increases, bubbles created near the free surface are distributed throughout the test section and permit the study of the spatial and temporal properties of turbulent flows using visualization techniques. In addition to classic travelling Taylor vortices, intermittent pulses of vortices with higher phase velocities are also observed. These patterns are described in terms of the rotational speed and the intensity of the throughflow.

An experimental study of louvers for fish diversion

2007 ◽  
Vol 34 (6) ◽  
pp. 770-776 ◽  
Author(s):  
D Shepherd ◽  
C Katopodis ◽  
N Rajaratnam
Keyword(s):  
Experimental Study ◽  
Rainbow Trout ◽  
Phase I ◽  
Key Words ◽  
Turbulent Flows ◽  
Field Testing ◽  
Approach Channel ◽  
Approach Velocity ◽  
Key Words Fish ◽  
Two Phases

This paper presents the results of an experimental study of louvers that are used for diversion of fish from water intakes and canals. This investigation was conducted in two phases. Phase I involved the field testing of a louver with curved slats for the guidance of hatchery-reared juvenile rainbow trout (Onchorhyncus mykiss) for louver angles θ of 7.2° and 17.0°. Phase II was a laboratory study with flat slats placed perpendicular to the approaching flow with θ of 10.0° and 15.0°. The velocity in the bypass in terms of the approach velocity increased to 1.7 and 2.5, respectively, for the curved and flat louvers for a bypass width b equal to 5% of the width of the approach channel B. The discharge in the bypass channel Qb in terms of the discharge in the approach channel Q was 0.15 and 0.20 for b/B = 0.10 for the curved and flat louvers, respectively, and Qb/Q = 0.07 for b/B = 0.05 for both the curved and flat louver slats. Key words: fish diversion, louvers, canals, open channels, water intakes, turbulent flows.

The effect of thermal boundary conditions on forced convection heat transfer to fluids at supercritical pressure

2016 ◽  
Vol 800 ◽  
pp. 531-556 ◽  
Author(s):  
Hassan Nemati ◽  
Ashish Patel ◽  
Bendiks J. Boersma ◽  
Rene Pecnik
Keyword(s):  
Heat Transfer ◽  
Boundary Conditions ◽  
Turbulent Flows ◽  
Thermophysical Properties ◽  
Thermal Effusivity ◽  
Temperature Fluctuations ◽  
Supercritical Pressure ◽  
Normal Velocity ◽  
Thermal Boundary Conditions ◽  
Wall Boundary Conditions

We use direct numerical simulations to study the effect of thermal boundary conditions on developing turbulent pipe flows with fluids at supercritical pressure. The Reynolds number based on pipe diameter and friction velocity at the inlet is$Re_{{\it\tau}0}=360$and Prandtl number at the inlet is$Pr_{0}=3.19$. The thermodynamic conditions are chosen such that the temperature range within the flow domain incorporates the pseudo-critical point where large variations in thermophysical properties occur. Two different thermal wall boundary conditions are studied: one that permits temperature fluctuations and one that does not allow temperature fluctuations at the wall (equivalent to cases where the thermal effusivity ratio approaches infinity and zero, respectively). Unlike for turbulent flows with constant thermophysical properties and Prandtl numbers above unity – where the effusivity ratio has a negligible influence on heat transfer – supercritical fluids shows a strong dependency on the effusivity ratio. We observe a reduction of 7 % in Nusselt number when the temperature fluctuations at the wall are suppressed. On the other hand, if temperature fluctuations are permitted, large property variations are induced that consequently cause an increase of wall-normal velocity fluctuations very close to the wall and thus an increased overall heat flux and skin friction.

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