Some Experiments on Artificially Roughened Lucy Ashton Geosims

1980 ◽  
Vol 24 (03) ◽  
pp. 170-180
Author(s):  
A.J. Smits ◽  
N. Matheson ◽  
P.N. Joubert
Keyword(s):  
Pipe Flow ◽  
Wave Drag ◽  
Mirror Image ◽  
Turbulent Pipe Flow ◽  
Viscous Resistance ◽  
Local Parameter ◽  
Image Model ◽  
Outer Flow ◽  
Total Drag ◽  
Towing Tank

A mirror-image model of the Lucy Ashton was covered with two different "mesh-type" roughnesses and tested in a wind tunnel. Total drag and velocity profile measurements are presented. Total drag results are also given for a normal Lucy Ashton model with the same roughness mesh tested in a towing tank. The influence of roughness on the wave drag component was found to be small, implying that the "interdependence" of wavemaking and viscous resistance is small. The importance of considering roughness as a local parameter is demonstrated, and the roughness function results agree well with the fully developed turbulent pipe flow results of Perry and Abell, even though the ship boundary-layer outer flow did not follow any recognized wake function.

Particle Destabilization in Turbulent Pipe Flow

1989 ◽  
Vol 21 (6-7) ◽  
pp. 435-442 ◽  
Author(s):  
B. Döll
Keyword(s):  
Pipe Flow ◽  
Reaction Rate ◽  
Turbulent Pipe Flow ◽  
Cationic Polymers ◽  
Flow Conditions ◽  
Polyelectrolyte Adsorption ◽  
Charge Neutralization ◽  
Silica Suspensions ◽  
Kinetics Of ◽  
Turbulent Flow Conditions

Silica suspensions (pH = 6.8) and three different cationic polymers were used to study the kinetics of charge neutralization by polyelectrolyte adsorption. The experiments were performed in a continuous flow pipe reactor under steady state turbulent flow conditions. The charge neutralization was monitored by electrophoretic mobility (EPM) measurements of the suspended particles as a function of time after polyelectrolyte audition. The results show the dependency of the destabilization reaction rate on flow and polymer characteristics.

scholarly journals Intermediate scaling and logarithmic invariance in turbulent pipe flow

2021 ◽  
Vol 913 ◽  
Author(s):  
Sourabh S. Diwan ◽  
Jonathan F. Morrison
Keyword(s):  
Pipe Flow ◽  
Turbulent Pipe Flow

Abstract

scholarly journals Experimental and theoretical progress in pipe flow transition

2008 ◽  
Vol 366 (1876) ◽  
pp. 2671-2684 ◽  
Author(s):  
A.P Willis ◽  
J Peixinho ◽  
R.R Kerswell ◽  
T Mullin
Keyword(s):  
Pipe Flow ◽  
Quantitative Agreement ◽  
Travelling Wave ◽  
Turbulent Pipe Flow ◽  
Transition To Turbulence ◽  
Reynolds Number Flow ◽  
Threshold Amplitude ◽  
Number Flow ◽  
The Stability ◽  
Laminar State

There have been many investigations of the stability of Hagen–Poiseuille flow in the 125 years since Osborne Reynolds' famous experiments on the transition to turbulence in a pipe, and yet the pipe problem remains the focus of attention of much research. Here, we discuss recent results from experimental and numerical investigations obtained in this new century. Progress has been made on three fundamental issues: the threshold amplitude of disturbances required to trigger a transition to turbulence from the laminar state; the threshold Reynolds number flow below which a disturbance decays from turbulence to the laminar state, with quantitative agreement between experimental and numerical results; and understanding the relevance of recently discovered families of unstable travelling wave solutions to transitional and turbulent pipe flow.

scholarly journals Resistance reduction on trimaran ship model by biopolymer of eel slime

2015 ◽  
Vol 12 (2) ◽  
pp. 95-102
Author(s):  
Y. Yanuar ◽  
G. Gunawan ◽  
M. A. Talahatu ◽  
R. T. Indrawati ◽  
A. Jamaluddin
Keyword(s):  
Drag Reduction ◽  
Frictional Resistance ◽  
Skin Surface ◽  
Fish Skin ◽  
Total Drag ◽  
Towing Tank ◽  
Ship Model ◽  
Resistance Reduction ◽  
Towing Tank Test ◽  
Tank Test

Resistance reduction in ship becomes an important issue to be investigated. Energy consumption and its efficiency are related toward drag reduction. Drag reduction in fluid flow can be obtained by providing polymer additives, coating, surfactants, fiber and special roughness on the surface hull. Fish skin surface coated with biopolymers viscous fluid (slime) is one method in frictional resistance reduction. The aim of this is to understanding the effect of drag reduction using eel slime biopolymer in unsymmetrical trimaran ship model. The Investigation was conducted using towing tank test with variation of velocity. The dimension of trimaran model are L = 2 m, B = 0.20 m and T = 0.065 m. The ship model resistance was precisely measured by a load cell transducer. The comparison of resistance on trimaran ship model coated and uncoated by eel slime are shown on the graph as a function of the total drag coefficient and Froude number. It is discovered the trimaran ship model by eel slime has higher drag reduction compared to trimaran with no eel slime at similar displacement. The result shows the drag reduction about 11 % at Fr 0.35.

Rapid temporal acceleration of a turbulent pipe flow

2004 ◽  
Vol 514 ◽  
pp. 65-75 ◽  
Author(s):  
DAVID GREENBLATT ◽  
EDWARD A. MOSS
Keyword(s):  
Pipe Flow ◽  
Turbulent Pipe Flow
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