Grooved surfaces

[FW17]

I think the primary function of the grooves are to provide for an expansive internal of the whale.

Secondary function being whale's skin has parallel lines which help eliminate turbulence and allow it to swim faster and more efficiently. Laminar flow occurs when fluid flows in parallel layers, eliminating disruption in the flow, also known as called turbulence. The Finishline’s parallel ribbed chest, back, and legs significantly reduce flow turbulence while increasing speed and efficiency, improving hydrodynamics and speeding your passage through the water, with less fatigue.

[sknguy]

Hydrodynamics are not the same as aerodynamics. Compressible fluids do not behave the same as incompressible fluids.

I suppose the same would hold true for shark skin as well. The principle works for performance swimsuits, but that's in water.

[Richard]

Hydrodynamics are not the same as aerodynamics. Compressible fluids do not behave the same as incompressible fluids.

I thought that would be a major factor in a conversation about water tunnels. Turns out the difference isn't so significant after all (at automobile speeds).

http://www.f1technical.net/forum/viewto ... =6&t=10741

[FW17]

Hydrodynamics are not the same as aerodynamics. Compressible fluids do not behave the same as incompressible fluids.

I suppose the same would hold true for shark skin as well. The principle works for performance swimsuits, but that's in water.

In October 2009 the European Commission decided that fuel consumption by aviation and shipping has to be reduced by 10% and 20% respectively by 2020.

A significant contribution to this challenging goal could be a coating that reduces drag.

For about 20 years it has been known that special microstructures (“riblets”) can lower drag by up to 10%. A new process for the production of such microstructured coatings on large surfaces is presented in this article. This process allows coating application, embossing, and partial curing in a single step. The coating material consists of VOC-free nanocomposites that give the coating the necessary abrasion resistance and weathering stability.

Drag measurements have been carried out in a ship model basin and in a wind-tunnel respectively. In these experiments, smooth coatings were compared to riblet-structured coatings. These structures were adapted to the flow-parameters of the fluid. A surface-drag reduction of 5.2% for a torpedo-shaped specimen was measured in a large hydrodynamic and cavitation tunnel. In a wind-tunnel experiment a reduction of the total drag of a wing-profile by 6.2% was measured.

Both experiments indicate the high potential for fuel savings in the transportation sector.
http://www.sciencedirect.com/science/ar ... 4010003206

Probably these are already in use in F1

[rjsa]

Hydrodynamics are not the same as aerodynamics. Compressible fluids do not behave the same as incompressible fluids.

Another thing to consider is why do marine mammals, like whales and dolphins, have horizontal tail fins for propulsion, while marine fishes have vertical tail fins for propulsion?

Nope, air is approximated to uncompressible up to Mach 0.3 and that's pretty much where race cars top. Equations are exactly the same.

[flynfrog]

Just to add to rjsa

stolen from wiki

In fluid dynamics, the drag equation is a formula used to calculate the force of drag experienced by an object due to movement through a fully enclosing fluid. The formula is accurate only under certain conditions: the objects must have a blunt form factor and the fluid must have a large enough Reynolds number to produce turbulence behind the object. The equation is

where
FD is the drag force, which is by definition the force component in the direction of the flow velocity,[1]
ρ is the mass density of the fluid, [2]
v is the velocity of the object relative to the fluid,
A is the reference area, and
CD is the drag coefficient – a dimensionless coefficient related to the object's geometry and taking into account both skin friction and form drag.

the differences between water and air is the p value they are all fluids.

[aussiegman]

Let's rewind: What's the purpose of the grooves on the whale?

I think this is the most important point. Look at what they are there for, their placement and where they are not placed.

I mentioned it earlier. The grooves allow the mouth and throat to expand to take in a greater amount of sea water. They don't serve a hydrodynamic function.

I think the primary function of the grooves are to provide for an expansive internal of the whale.

This is the primary function of the grooves on a whales underside, to allow for expansion when feeding and filtering large volumes of incompressible fluids, namely water with plankton in it, prior to it being filtered through the whales comb.

If the purpose was for a decrease in drag, then (according to evolutionary theories) it would be more likely that both the whole underside and upper surface would be covered in said grooves. As it is, the grooves only exist where needed for expansion and extend no further.

Secondary function being whale's skin has parallel lines which help eliminate turbulence and allow it to swim faster and more efficiently……

IMHO this is not a secondary function but a beneficial by-product. The whale cannot live without the expansion grooves, so with or without the secondary benefit they would still be there.
What it may have done is dictated their size, shape and placement such that they are only where required. This is another reason that the expectation would be that they increase drag otherwise they would be elsewhere on the whale body.

[The Cone of Silence]

I do a lot of yacht racing and recall there was some discussion a few years ago about the way that whale fins have nobbly lumps on their leading edge called tubercles.

I believe that those studying them were trying to figure out if the lumps acted like the prow of a large boat, disturbing the surrounding water .... a laminar flow/ turbulent flow thing. Forgive my clumsy inexperience with this. Yacht designers were thinkng it could be a useful addition to the boat fins - keel, rudders and canards. While I haven't seen this in action on any recent successful racing yachts, it has made the transition from hydrodynamics to aerodynamics.

I wonder if there could be any relevant applications of this within F1?

An interesting article here:
http://www.technologyreview.com/news/40 ... -turbines/

[cwb]

I do a lot of yacht racing and recall there was some discussion a few years ago about the way that whale fins have nobbly lumps on their leading edge called tubercles.

I believe that those studying them were trying to figure out if the lumps acted like the prow of a large boat, disturbing the surrounding water .... a laminar flow/ turbulent flow thing. Forgive my clumsy inexperience with this. Yacht designers were thinkng it could be a useful addition to the boat fins - keel, rudders and canards. While I haven't seen this in action on any recent successful racing yachts, it has made the transition from hydrodynamics to aerodynamics.

I wonder if there could be any relevant applications of this within F1?

An interesting article here:
http://www.technologyreview.com/news/40 ... -turbines/

It is an intersting article and they make quite a few interesting claims. The one they mention the most is extending the angle of attack range of the aerofoil. My first read is that the protusions on the leading edge are essentially vortex generators, generating turbulence to enable the flow to stay attached under greater adverse pressure gradients experienced and higher angles of attack. Most likely this comes at the expense of increased drag, but they are unlikely to mention that in the brochure.

It appears to have its greatest application for symmetrical aerofoil sections which are the most angle of attack limited. Normally this issue is overcome by adding camber to the section, but in the case of a wing/foil which is functionally required to be symmetrical because it has to provide lift in both directions, i.e. a hydrodynamic control surface such as a whale fin, or a yacht keel or rudder then it would appear these things provide a greater angle of attack range.

This doesnt explain why they seem to have found appplication in wind turbine blades which I wouldnt have thought needed to be symmetrical, but the claims of reduced noise are probably related to better attached flow as well.

[olefud]

This doesnt explain why they seem to have found appplication in wind turbine blades which I wouldnt have thought needed to be symmetrical, but the claims of reduced noise are probably related to better attached flow as well.

I’m having trouble following you. Even a symmetrical airfoil has a “long” low pressure side as a result of the AoA. Keeping the flow attached would seem to be a problem of the AoA and the shape of the long side rather than the shape of the positive pressure side.

[cwb]

This doesnt explain why they seem to have found appplication in wind turbine blades which I wouldnt have thought needed to be symmetrical, but the claims of reduced noise are probably related to better attached flow as well.

I’m having trouble following you. Even a symmetrical airfoil has a “long” low pressure side as a result of the AoA. Keeping the flow attached would seem to be a problem of the AoA and the shape of the long side rather than the shape of the positive pressure side.

You are correct, any lifting section has a "long" low pressure side. By this I assume you mean the longer path taken by the streamline on the low pressure side from the stagnation point downstream from the leading edge on the high pressure side, back around the leading edge and then down the low pressure side of the foil. In fact it is exactly this tortous journey from the stagnation point back around the leading edge that creates most of the lift on a foil. The flow has to accelerate so much to take this path that the pressure drop is greatest in this region. You are probably familiar with a plot of pressure distribution over a lifting foil section, there is a large peak in negative pressure around the leading edge and this is where maost of the lift (downforce) comes from.

As the AoA increases, the stagnation point shifts further away from the leading edge, the path back around the leading edge gets more tortuous, the flow has to work harder to get around to the low pressure side, more acceleration, lower pressure, more lift. Eventually at some AoA, the flow has to work too hard to stay attached to the low pressure side, it gives up, detaches, and you no longer have a useful section.

When you add camber to an aerofoil section what happens is the leading edge is oriented more beneficially to the oncoming airstream, i.e. more directly into it, and the flow doesnt have to work as hard to to get through the "danger zone" from the stagnation point back around the leading edge and so on. Because it doesnt have to work so hard it is less inclined to detach and you get an increased AoA range as a result.

This is actually pretty much what you said, "keep the flow attached would seem to be a problem of the AoA and the shape of the long side" What I have tried to outline is that when you add camber, the shape of the "long" side, especially in the critical region around the leading edge and the front 25% of the low pressure side, is more beneficial to the flow staying attached, hence better AoA performance.

[PlatinumZealot]

Hydrodynamics are not the same as aerodynamics. Compressible fluids do not behave the same as incompressible fluids.

I suppose the same would hold true for shark skin as well. The principle works for performance swimsuits, but that's in water.

In October 2009 the European Commission decided that fuel consumption by aviation and shipping has to be reduced by 10% and 20% respectively by 2020.

A significant contribution to this challenging goal could be a coating that reduces drag.

For about 20 years it has been known that special microstructures (“riblets”) can lower drag by up to 10%. A new process for the production of such microstructured coatings on large surfaces is presented in this article. This process allows coating application, embossing, and partial curing in a single step. The coating material consists of VOC-free nanocomposites that give the coating the necessary abrasion resistance and weathering stability.

Drag measurements have been carried out in a ship model basin and in a wind-tunnel respectively. In these experiments, smooth coatings were compared to riblet-structured coatings. These structures were adapted to the flow-parameters of the fluid. A surface-drag reduction of 5.2% for a torpedo-shaped specimen was measured in a large hydrodynamic and cavitation tunnel. In a wind-tunnel experiment a reduction of the total drag of a wing-profile by 6.2% was measured.

Both experiments indicate the high potential for fuel savings in the transportation sector.
http://www.sciencedirect.com/science/ar ... 4010003206

Probably these are already in use in F1

Thank you... I told the people this on page one, but they didn't want to listen! =D>

[Richard]

I do a lot of yacht racing and recall there was some discussion a few years ago about the way that whale fins have nobbly lumps on their leading edge called tubercles.

I believe that those studying them were trying to figure out if the lumps acted like the prow of a large boat, disturbing the surrounding water .... a laminar flow/ turbulent flow thing.

You'll be wanting to read this http://www.f1technical.net/forum/viewto ... 26#p246826

[flynfrog]

stolen from the thread richard linked. Pretty much all vgs dimples ect work when an airfoil is pushed to far.

If you look how icing is simulated on flight test air craft you can see that a rough surface is not normally going to be advantageous. As a wing ices it will lose 20-30% of its lift while drag goes through the roof.


Ciro had a way with words I do not posses

I think they are vortex generators. You use them to increase energy in the air flow (twirl it) so the laminar flow on the surface doesn't detach at large angles of attack. They also have more benefits, if you believe the inventor. Read the link (or the one provided by Holm86).

I repost what we wrote here: http://www.f1technical.net/forum/viewto ... f=6&t=5416

They are not legal.

I think this is similar enough to the idea you propose, taken from "A whale of a tale".

WhaleCorps turbine blade


Ginsu said in that thread that there was a third, previous thread on the subject, which I could not find (he did not provide a link to it). DaveKillens mentioned vortex generators, they all seem similar to a profane: eagles, sharks, tunas, whales, they all "taste like chicken" to me.

This is an image Dave provided that I think sums up the "principle" behind vortex generators. Maybe humpbacks humps (shouldn't they be called "humpfins"?) work in a similar way:



I think most of them (VGs) are used to avoid stall at extreme angles of attack, as Giblet mentions. In the earlier thread some people said they increase drag when the angle of attack is low.

Finally, on the subject of bionics, I smiled with these pictures: http://www.freakingnews.com/Insect-Airc ... --1133.asp

[aussiegman]

Along the same lines:

http://www.news.com.au/travel/news/avia ... 6580256253