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Topic: Skin friction

Related Topics

Parasitic drag

Transition point

Drag equation

Drag coefficient

Laminar flow

Angle of attack

Dimensionless number

Boundary layer transition

	Common Skin Problems from Sports
		A boil is a skin infection, usually of a hair follicle, caused by common bacteria.
		Wrestlers are particularly susceptible to boils because as they sweat, their skin comes in contact with athletic mats -- which may harbor bacteria when they are not properly cleaned after use -- or other wrestlers who can transmit the infection.
		Most athletic activities include movements that may cause the skin to develop heat and friction against athletic equipment: tennis rackets, shoes, oars or paddles, etc. Compounded by perspiration, this friction commonly results in blisters that can be quite painful and diminish the athlete's ability to compete.
	healthlink.mcw.edu /article/972576522.html (1616 words)

	World Intellectual Property Organization (Site not responding. Last check: 2007-11-07)
		The reduction of surface friction on the outer surface of an aircraft allows improved fuel efficiency, for example up to 50% of fuel burnt on a commercial airliner is used to overcome skin friction.
		Skin friction reductions have also been realised by injecting polymer chains into fluid flows to interrupt the near wall structures, or by injecting micro-bubbles into a liquid flow.
		Alternatively, skin friction may be reduced by oscillating the surface in a spanwise direction or even oscillating the flow in the spanwise direction, for example, using Lorenz force control of sea water.
	www.wipo.int /ipdl/IPDL-CIMAGES/view/pct/getbykey5?KEY=03/106260.031224&ELEMENT_SET=DECL (7329 words)

	Friction_Skin_Growth
		Understanding the stages of friction skin growth during fetal development is of utmost importance to the friction ridge identification specialist.
		The task of explaining friction skin persistency and uniqueness would be a difficult one to say the least without this knowledge.
		The embryonic skin at 4 to 5 weeks consists of a single layer of surface ectoderm (later to form the epidermis) overlying the mesenchyme (connective tissue derived from mesoderm and forms the connective tissue in the dermis).
	www.ridgesandfurrows.homestead.com /Friction_Skin_Growth.html (561 words)

	Ridges and Furrows - Development of Friction Skin
		They are called 'friction' ridges because of their biological function to assist in our ability to grasp and hold onto objects.
		Friction ridges are in their definitive form on the fetus before birth.
		(90%) - responsible for waterproofing and toughening the skin
	www.ridgesandfurrows.homestead.com /friction_skin.html (1228 words)

	MAK et al. Review of prosthetic socket biomechanics (Site not responding. Last check: 2007-11-07)
		The skin and the underlying soft tissues of the residual limb are not particularly adapted to the high pressures, shear stress, abrasive relative motions, and the other physical irritations encountered at the prosthetic socket interface.
		Friction is a phenomenon in which tangential force acting between bodies in contact opposes their relative motion or impending motion.
		Frictional rubbing is one of the most common insults to which the human skin is exposed (158).
	www.vard.org /jour/01/38/2/mak382.htm (8284 words)

	NAP Skim View of:
		The mechanism for the skin friction reduction was briefly discussed, including the density effect, bubble size effect, and the reduction of the Reynolds stress.
		The skin friction reduction data at various flow speed collapses nearly to a single line, and increases as the air injection rate increases, reaching 80% at the maximum.
		The reason for the higher decay of the skin friction reduction effect at the higher speed is suspected to be the higher diffusion of the bubbles away from the wall by the higher turbulence intensity and/or smaller bubble size.
	www.nap.edu /nap-cgi/skimit.cgi?isbn=NI000511&chap=2-22 (900 words)

	Skin Friction of Driven Piles in Chiang Mai Stiff Clay (Site not responding. Last check: 2007-11-07)
		There are many method to estimate the skin friction such as total stress method, effective stress method or mixed approaches between total stress and effective stress and those method had different assumption.
		It was found that in part I, the unit skin friction was about 5.77 to 10.27 tons per square meter and it is demonstrated that the total stress method used by correlation between adhesion factor and undrained shear strength is found to estimate the skin friction reasonably well.
		In part III, from the tension test the unit skin friction had average 11.57 tons per square meter and it was found that in the estimated skin friction the total stress method and effective stress method had lower value than observed.
	www.grad.cmu.ac.th /abstract/2000/eng/abstract/eng01004.html (435 words)

	EJGE Paper 0214 (Site not responding. Last check: 2007-11-07)
		In the analysis, the negative skin friction was assumed to increase linearly with soil settlement along pile shaft to a constant maximum value.
		The negative skin friction at a depth induced by soil slip along the pile shaft is determined from vertical force equilibrium of a pile segment involving the axial load, pile weight, and friction force.
		To determine the variations of negative skin friction as well as axial pile load with depth, the governing differential equations (6) and (7) are solved numerically by following the approach adopted by Vaziri and Xie (1990) in their analysis of axially loaded piles.
	www.ejge.com /2002/Ppr0214/Ppr0214.htm (2256 words)

	Reasons to challenge digital fingerprint evidence
		Although skin covers the entire body, only the fingers and palms of the hands, and the toes and soles of the feet are ridged and called friction skin.
		She further explains the evolutionary process of friction ridges and explained the growth of ridge units, that patterns were affected by external forces and pressure from neighboring developing ridges.
		By using the tenet that acknowledges that every area of friction skin is unique and that the dynamics of every comparison is, in itself, unique and is influenced by the quality and quantity of the features present is in itself a standard based on the scientific research into the formation of friction skin.
	www.clpex.com /Articles/ScientificPrinciplesbyTomFerriola.htm (10787 words)

	Nat' Academies Press, Twenty-Fourth Symposium on Naval Hydrodynamics (2003)
		As shown in Fig.l, the skin friction reduction ~- fect of microbubbles increases as the amount of i~- jected air volume ncreases, and reaches 80%, but it should be noted that the measurement was made at only 50mm to 65mm downstream of the point of bubble injection.
		Skin friction sensors (for detail, see 2.3) were placed at xa =0.Sm, 1.0m, and 1.5m from the center of the injection plate, along the line 75mm from the center line, in order to avoid the wake of the propeller dynamorreter.
		Skin friction reduction mechanism of micro- bubbles The skin friction reduction mechanism of micro- bubbles is not yet fully understood.
	www.nap.edu /openbook/NI000511/html/2.html (9098 words)

	3-D Flow Separation, Aerodynamics
		In 2-D flows separation is identified by a region of backflow, and at the wall by a zero skin friction.
		When the skin friction lines converge to, or diverge from a point the point is called node (nodal point of separation or attachment, respectively).
		Skin friction lines diverging from nodal points cannot cross, due to the presence of a saddle point between them.
	aerodyn.org /Wings/3dsepar.html (486 words)

	clouterre
		Numerous experimental studies were carried out on the mobilization of skin friction in nails within the Project CLOUTERRE that make it possible to predict accurately and completely the results of previous studies (Plumelle, 1979, 1984).
		As in the case of piles, the mobilization of skin friction requires only a very small relative displacement of the nail in relation to the soil, of the order of a few millimeters, as was confirmed by the pull-out tests in the minicalibration chamber previously mentioned.
		It is the internal deformations of the soil nailed wall, and especially the horizontal extension, that induce the mobilization of friction along the nails and the tension of the latter.
	www.terrasol.fr /Anglais/clouterre221.htm (1461 words)

	The Physician and Sportsmedicine: Athletic Skin Injuries
		Blister prevention involves reducing moisture and friction applied to the skin by gradually increasing the intensity of one's exercise routine, especially when breaking in a new pair of shoes or a racket.
		Friction and pressure work with other exogenous factors, including occlusion and heat—elements that are nearly universal under athletic apparel from leotards to football helmets.
		Although friction applied with pressure, occlusion, and heat may be present in a number of athletic environments, acne mechanica seems to be particularly prevalent among football players.
	www.physsportsmed.com /issues/2004/0504/basler.htm (2274 words)

	Skin Friction and Roughness Drag
		The skin friction coefficients are sometimes based on experimental data for flat plates with various amounts of roughness.
		For fully turbulent plates, the skin friction coefficient may be approximated by one of several formula that represent simple fits to the experimentally-derived curves shown in the above figure.
		Consequently the use of the present method implies the same degree of proficiency in design as that of the airplanes from which the roughness drag correlation was obtained.
	adg.stanford.edu /aa241/drag/skinfriction.html (670 words)

	Korkegi, Robert H (1954-01-01) Transition studies and skin friction measurements on an insulated flat plate at a ...
		An investigation of transition and skin friction on an insulated flat plate, 5 x 26 inches, was made in the GALCIT 5 x 5 inch Hypersonic Wind Tunnel, Leg No. 1, at a nominal Mach number of 5.8.
		Direct skin friction measurements were made by means of the floating element technique incorporating a null system using chain loading, over a range of Reynolds numbers (based on distance from leading edge) from 10[superscript 6] to 4 x 10[superscript 6].
		The turbulent skin friction coefficient was found to be approximately 0.40 of that for incompressible flow for a constant value of R[subscript theta], and 0.46 for an effective Reynolds number between 5 and 6 x 10[superscript 6].
	etd.caltech.edu /etd/available/etd-01072004-114554 (452 words)

	The "Fast-Skin" Body Suit: Hip, hype, but does it reduce drag during front crawl swimming? (Site not responding. Last check: 2007-11-07)
		Friction of water particles forms the basis for forces induced by movement in water.
		Apart from pressure drag, the swimmer is subjected to friction drag (Ff), attributed to the forces tending to slow the water flowing along the surface of a swimmer's body.
		The magnitude of the friction drag depends on the velocity of the flow relative to that of the body, the surface area of the body, and the characteristics of the surface.
	www.coachesinfo.com /category/swimming/146 (3779 words)

	Turbulent Skin Friction (Site not responding. Last check: 2007-11-07)
		The calculation of skin friction on an airplane from first principles is an incredibly complex task and requires powerful methods of computational fluid mechanics.
		From the vast collection of measurements of skin friction, there have been many attempts to make a simple formula which fits the observed data.
		For the great majority of flight problems, the variation of friction with temperature is of little importance.
	www.pdas.com /turbsf.htm (503 words)

	SCAFO Online Articles
		This philosophy is based on the scientific research into the formation of friction skin, improved techniques of latent print development, and the refinement of our ability to perform comparative analysis of more detailed ridge structure.
		The latent print is analyzed to determine the area of friction skin it may have come from, the detail present, and the clarity of that detail.
		By having a thorough knowledge of the scientific basis of friction skin identification, latent print examiners are better able to explain and defend their conclusions with confidence on the witness stand.
	www.scafo.org /library/100301.html (1673 words)

	Comparison of Measured and Predicted Skin Friction Values for Axially Loaded Drilled Shaft Foundations in Gravelly Soils (Site not responding. Last check: 2007-11-07)
		Skin friction predictive equations have been available for determining the contribution of skin friction to the drilled shaft axial load carrying capacity for a number of years.
		It is presumed that the skin friction factors of gravelly soils would be higher than those for pure sands, because of the increased dilatancy of gravels prior to failure.
		These skin friction factors were compared with the various predictive equations currently employed for design purposes.
	www.pubs.asce.org /WWWdisplay.cgi?0500357 (372 words)

	Microblowing Technique Reduces Skin Friction
		One of the most challenging areas of research in aerodynamics is the reduction of skin friction, especially for turbulent flow.
		An MBT skin is one that has an unblown skin friction (i.e., the skin friction of a porous plate without blowing) not more than 20 percent above the skin friction of a solid flat plate.
		Results of the experiment indicate that skin friction reductions of 50 to 70 percent are possible over portions of the nacelle, with the addition of only small amounts of blowing air.
	www.lerc.nasa.gov /WWW/RT1997/5000/5850hwang.htm (530 words)

	Hairfacts: Friction for hair removal (Site not responding. Last check: 2007-11-07)
		For sensitive skin, “condition” the mitt by gently rubbing on palm for a few seconds to remove the coarser grit.
		I didn't want to irritate my dry skin, so I was careful to apply light pressure but to rub the skin briskly, in a circular motion.
		After showering, I applied unscented baby oil to my wet skin then patted dry with a towel; I followed that by using unscented generic-label moisturizer (most drugstores sell their own generic brand of Lubriderm; about $5 for a large bottle).
	www.hairfacts.com /methods/friction.html (2254 words)

	THE GSI LINEAR SKIN RHEOMETER - FRICTION ATTACHMENT (Site not responding. Last check: 2007-11-07)
		The difference between the average forward drag force, and the average reverse drag force is a measure of the dynamic friction.
		Friction is obtained by measuring the vertical load of the probe, and calculating the ratio of these two forces.
		The trace showing the changes in force at 'take-off' is an indication of the effects that occur as a result of static friction.
	www.zyworld.com /egoodyer/fric.HTM (197 words)

	Dhawan, Satish (1951-01-01) Direct measurements of skin friction. ...
		A device has been developed to measure local skin friction on a flat plate by measuring the force exerted upon a very small movable part of the surface of a flat plate.
		The measured skin friction coefficients show excellent agreement with Blasius' and Karman's results respectively.
		The device was then applied to high-speed subsonic flow and the turbulent skin friction coefficients were determined up to a Mach number of about 0.8.
	etd.caltech.edu /etd/available/etd-09262002-155504 (175 words)

	Re: What is the coefficient of friction of human skin?
		Friction between two surfaces is due to the bonding and interaction of molecules of the objects at those places (atomically) where the surfaces are in very close contact.
		An important thing to remember is that the force of friction is independent of the area of contact, and is proportional to the force exerted by one surface onto the other.
		I do not mean, wet, because then you are gliding on water, not skin, but when your skin is clammy moist, as opposed to dry.
	www.madsci.org /posts/archives/sep99/937228809.Bp.r.html (403 words)

	Skin friction (Site not responding. Last check: 2007-11-07)
		This drag is often referred to as skin friction , and is due to the viscous stresses acting on the surface of the plate.
		The turbulent mixing of the fluid near the surface of a solid body leads to more efficient momentum transport away from the body, increasing the gradient of the velocity profile at the surface and therefore the viscous stress on the plate.
		For boundary layers which remain attached to a body the drag due to skin friction can be reduced if the boundary layer can be persuaded to remain laminar.
	landau1.phys.virginia.edu /classes/311/notes/fluids2/node10.html (309 words)

	Prediction of Very High Reynolds Number Compressible Skin Friction, AIAA 98-2880, June 15-18, 1998, (Site not responding. Last check: 2007-11-07)
		Abstract : Flat plate skin friction calculations over a range of Mach numbers from 0.4 to 3.5 at Reynolds numbers from 16 million to 492 million using a Navier Stokes method with advanced turbulence modeling are compared with incompressible skin friction coefficient correlations.
		The semi-empirical correlation theories of van Driest; Cope; Winkler and Cha; and Sommer and Short T' are used to transform the predicted skin friction coefficients of solutions using two algebraic Reynolds stress turbulence models in the Navier-Stokes method PAB3D.
		In general, the predicted skin friction coefficients scaled well with each reference temperature theory though, overall the theory by Sommer and Short appeared to best collapse the predicted coefficients.
	techreports.larc.nasa.gov /ltrs/98/aiaa/NASA-aiaa-98-2880.refer.html (233 words)

	Interferometric Skin Friction Footprint For A Tripped Boundary Layer (Site not responding. Last check: 2007-11-07)
		Skin friction variations in the vicinity of isolated trip elements have been visualized with oil film interferometry.
		Lines of transparent silicone oil, applied perpendicular to the onset flow, were thinned to yield an oil film whose thickness distribution reflected regions of laminar and turbulent flow when visualized with interferometry.
		The laminar flow results shown in Figure 1, compared with trip elements of different shapes and widths d, all produce a downstream skin friction footprint characterized by more widely-spaced interference fringes (Figures 2-7), indicative of turbulent flow.
	www.tricity.wsu.edu /htmls/mme/apsgfm98.htm (462 words)

	Nonvisual 1963
		The stimulus is a depression of the skin; the experience is that of an object "touching" ("pressing," "contacting") the skin at the locus of stimulation.
		The stimulus is a moving depression of the skin with the addition of lateral tension and with changes in tension due to friction.
		A non-rigid body in contact with the skin of, say, the hand is caused to change shape by movement of the hand and fingers (e.g., palpating, kneading, or squeezing clay or putty).
	www.trincoll.edu /depts/ecopsyc/perils/folder2/nonvisual.html (1419 words)

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