High Reynolds Number Micro-Bubble and Polymer Drag Reduction Experiments

2008 ◽  
Author(s):  
Steven L. Ceccio ◽  
David R. Dowling ◽  
Marc Perlin ◽  
Michael Solomon
Keyword(s):  
Reynolds Number ◽  
Drag Reduction ◽  
High Reynolds Number ◽  
Polymer Drag Reduction ◽  
Micro Bubble ◽  
High Reynolds

scholarly journals High-Reynolds-number weakly stratified flow past an obstacle

1996 ◽  
Vol 317 ◽  
pp. 155-178 ◽  
Author(s):  
S. I. Chernyshenko ◽  
Ian P. Castro
Keyword(s):  
Reynolds Number ◽  
Drag Reduction ◽  
Turbulent Flows ◽  
High Reynolds Number ◽  
Bluff Body ◽  
Physical Mechanisms ◽  
Flow Past ◽  
Large Channel ◽  
Weak Stratification ◽  
High Reynolds

Stably stratified steady flow past a bluff body in a channel is considered for cases in which the stratification is not sufficiently strong to give solutions containing wave motions. The physical mechanisms by which stratification influences the flow are revealed. In particular, the drag reduction under weak stratification, observed in experiments, is explained. This is achieved by constructing an asymptotic laminar solution for high Reynolds number (Re) and large channel width, which explicitly gives the mechanisms, and using comparisons with numerical results for medium Re and experiments for turbulent flows to argue that these mechanisms are expected to be common in all cases. The results demonstrate the possibility, subject to certain restrictions, of using steady high-Re theory as a tool for studying qualitative features of real flows.

Bubble friction drag reduction in a high-Reynolds-number flat-plate turbulent boundary layer

2006 ◽  
Vol 552 (-1) ◽  
pp. 353 ◽  
Author(s):  
WENDY C. SANDERS ◽  
ERIC S. WINKEL ◽  
DAVID R. DOWLING ◽  
MARC PERLIN ◽  
STEVEN L. CECCIO
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Turbulent Boundary Layer ◽  
Drag Reduction ◽  
Flat Plate ◽  
High Reynolds Number ◽  
Friction Drag ◽  
High Reynolds ◽  
Friction Drag Reduction

Flow-induced degradation of drag-reducing polymer solutions within a high-Reynolds-number turbulent boundary layer

2011 ◽  
Vol 670 ◽  
pp. 337-364 ◽  
Author(s):  
BRIAN R. ELBING ◽  
MICHAEL J. SOLOMON ◽  
MARC PERLIN ◽  
DAVID R. DOWLING ◽  
STEVEN L. CECCIO
Keyword(s):  
Boundary Layer ◽  
Molecular Weight ◽  
Reynolds Number ◽  
Turbulent Boundary Layer ◽  
Drag Reduction ◽  
High Reynolds Number ◽  
Polymer Degradation ◽  
Rheological Analysis ◽  
Downstream Distance ◽  
High Reynolds

Polymer drag reduction, diffusion and degradation in a high-Reynolds-number turbulent boundary layer (TBL) flow were investigated. The TBL developed on a flat plate at free-stream speeds up to 20ms−1. Measurements were acquired up to 10.7m downstream of the leading edge, yielding downstream-distance-based Reynolds numbers up to 220 million. The test model surface was hydraulically smooth or fully rough. Flow diagnostics included local skin friction, near-wall polymer concentration, boundary layer sampling and rheological analysis of polymer solution samples. Skin-friction data revealed that the presence of surface roughness can produce a local increase in drag reduction near the injection location (compared with the flow over a smooth surface) because of enhanced mixing. However, the roughness ultimately led to a significant decrease in drag reduction with increasing speed and downstream distance. At the highest speed tested (20ms−1) no drag reduction was discernible at the first measurement location (0.56m downstream of injection), even at the highest polymer injection flux (10 times the flux of fluid in the near-wall region). Increased polymer degradation rates and polymer mixing were shown to be the contributing factors to the loss of drag reduction. Rheological analysis of liquid drawn from the TBL revealed that flow-induced polymer degradation by chain scission was often substantial. The inferred polymer molecular weight was successfully scaled with the local wall shear rate and residence time in the TBL. This scaling revealed an exponential decay that asymptotes to a finite (steady-state) molecular weight. The importance of the residence time to the scaling indicates that while individual polymer chains are stretched and ruptured on a relatively short time scale (~10−3s), because of the low percentage of individual chains stretched at any instant in time, a relatively long time period (~0.1s) is required to observe changes in the mean molecular weight. This scaling also indicates that most previous TBL studies would have observed minimal influence from degradation due to insufficient residence times.

VLES of drag reduction for high Reynolds number flow past a square cylinder based on OpenFOAM

2019 ◽  
Vol 190 ◽  
pp. 106450
Author(s):  
Yi Jin ◽  
Zhongyu Cheng ◽  
Xingsi Han ◽  
Junkui Mao ◽  
Feng Jin
Keyword(s):  
Reynolds Number ◽  
Drag Reduction ◽  
High Reynolds Number ◽  
Square Cylinder ◽  
Reynolds Number Flow ◽  
Flow Past ◽  
Number Flow ◽  
High Reynolds
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