Clarkson cleared by Ofcom

Last November, Jeremy Clarkson commented on BBC TV's The One Show, that striking public sector employees should be taken out and shot in front of their families. Clarkson's comment provoked 30,000 complaints, and he was later moved to apologise and explain that "I didn't for a moment intend these remarks to be taken seriously."

Now, the phrase, 'X should be taken out and shot', is a well-known example of rhetorical hyperbole. Unless it's uttered by either Don Corleone, a Colombian druglord, or the head of a militaristic dictatorship, it's not meant to be interpreted as a literal piece of advice. Clarkson was not issuing an instruction, he was making a political point in a caustic manner. The fact that 30,000 people still complained, should therefore be seen as the outcome of an epidemiological experiment, designed to obtain a lower bound on the number of people in the UK who suffer from ingrowing skulls.

You can disagree with Clarkson, but to be 'outraged' or 'offended' by the remark, you need to be incapable of discriminating between that which is literal, and that which is ironic or sarcastic.

It is a damning indictment of the insipid idiocracy in which we live, that Ofcom director Christopher Woolard, actually had to point out today that it was "clear to most viewers that his comments were not an expression of seriously held beliefs or views that should be literally interpreted".

The names and addresses of the cretinous 30,000 should be retained, and transferred to the National Health Service, so that precious MRI resources are not wasted on this neurologically regressive cohort.

Front-wing side-edge vortices

Aerodynamically speaking, a Formula 1 car is an interconnected system of vortices and vortex layers. The vorticity is created by viscous shear in thin boundary layers adjacent to the solid surfaces of the car; such boundary layers are attached vortex layers. The downforce (or lift) generated by a wing is often attributed to the presence of circulation in the airflow around the wing, but the circulation itself is nothing more than the net vorticity in the boundary layers above and below the wing.

When a vortex layer separates from a solid surface, it becomes a free vortex layer, and a separated vortex layer can roll-up into a volume of concentrated vorticity, called a vortex. These vortices possess a low pressure core, in some sort of balance with the centrifugal 'force' of the fluid elements spiralling around the vortex on helical trajectories. Oriented in a streamwise direction, such vortices can be particularly useful, both for the direct generation of downforce, and to act as air curtains, sealing off other low pressure areas.

Now, the front-wing of a car sees the air first, and therefore sets the conditions for the rest of the car, hence the vortices it generates are particularly important. Streamwise vortices are generated by lateral pressure gradients within the front-wing assembly, and these exist (i) across the endplate, (ii) at the transition between the wing-section and the neutral inner-section dictated by regulation, (iii) at the inner tips of the front-wing flaps, and (iv) at the arched sections in the front-wing.

To keep a vortex alive, one has to maintain the correct ratio between axial (streamwise) velocity, and the azimuthal velocity. If the azimuthal velocity gets too high, or the axial velocity gets too low, the vortex can breakdown.

For obvious reasons of commercial confidentiality, Formula 1 does a poor job at publishing its aerodynamic discoveries. Fortunately, however, there has been some academic research on the vortices generated by the front-wing endplates, conducted by Professor Zhang and colleagues at the University of Southampton. On the basis of wind-tunnel flow visualisation and measurement methods, such as Laser-Doppler Anemometry, Zhang et al (2006) claim that in the case of a simple front-wing, (without a rotating wheel in close proximity), the side-edge vortices possess "a low streamwise speed core...This feature is important as the vortex could break down or dissipate quickly further downstream," (p38, Ground effect aerodynamics of race cars, Applied Mechanics Reviews, Vol 59.).
Which brings us to Adrian Newey's Williams FW14/B of 1991/1992, which featured, at a time when the regulations permitted it, long extensions to the front-wing endplates. One might hypothesise that these extensions strengthened and stabilised the front-wing endplate vortices. One method of postponing vortex burst is to connect a vortex to a low-pressure area downstream, and these extensions may have been intended to join the front-wing vortices to the low pressure areas which exist behind the front-wheels. Certainly, on the current generation of Red Bulls, a similar trick is employed at the rear, the side-edge vortices on the diffuser being connected up to the low pressure regions behind the rear wheels.

One also presumes that those extensions were directing the front-wing vortices at a particular region downstream, perhaps the lower edges of the sidepods, both to seal off the low pressure region under the floor, and possibly also to feed the flow which is sucked under the floor in front of the rear wheels, thereby feeding the diffuser side-edge vortices, making one powerful, car-length vortex. One wonders how much such thinking still informs the design philosophy at Red Bull...

Convergence

It's been New Car Week in Formula 1, with McLaren, Ferrari, Red Bull, Williams, Force India, Toro Rosso, Sauber, and Lotus, all revealing their 2012 protagonists. There was, however, a feeling of anti-climax to the ritual this year. McLaren unveiled something which looked like their 2011 car, but with re-shaped sidepods and a pair of blisters containing the exhaust outlets. And Red Bull initially issued what appeared to be airbrushed images of the RB8 from a Scalextric box, although even the photo-shopping couldn't conceal the letterbox in the nose, through which CVs can be posted to Adrian Newey.

There continue to be detail differences between the cars and their exhaust outlets, but it finally appears as if the Formula 1 regulations are now so restrictive that there is only one optimal solution in the design landscape, and all the teams have converged towards it. As the Red Bull Technical Director put it,

"Regulation restrictions like the lost exhaust are a bit frustrating in truth, because they are exactly that, they are restrictions, they're not giving new opportunities or revenues particularly, they're just closing a door...Regulation changes I enjoy, regulation restrictions I rather lament."

Thus, whilst the technically-inclined Formula 1 fan is perhaps better-informed today than has ever been the case, with Craig Scarborough and Gary Anderson providing massively informative analysis of the new vehicles (on Autosport.com, and in the pages of Autosport, respectively), the crying shame is that there is so little innovation to write about.

Gary Anderson, of course, has joined the BBC F1 team as their technical analyst, and got off to an excellent start by using the ancient technique of pen-and-paper to explain the aerodynamics of contemporary Formula 1 to a metrosexually-scarfed Jake Humphrey. Bravo!

Whitney

So, another music industry star implodes to a singularity.

This will provoke the habitual, systematised music-industry/media response: a form of mourning which includes the re-selling of the rise-and-fall story-template, and the re-issue and marketing of Biggest-Hits albums.

It's In Memoriam, but not as Tennyson would know it.

"Our genres of confidence in the world are shattering!"

Turn on to Radio 4 at a random moment during the day, and chances are that you'll alight upon one of three things: (i) a dreary, unimaginative analysis of political or economic news; (ii) a deeply earnest play; or (iii) a pompous discussion by self-important non-entities of pseudo-philosophical issues.

The last category, however, often unwittingly falls into the 'most original comedy' category, and a shining exemplar such can be found in the February 8th edition of 'Thinking Allowed' (geddit?). Here, 'cultural theorist' Lauren Berlant discharges the following array of dazzling intellectual gems:

"I think it's important not to think of the working class as having no fantasies."

"I don't think you'd want to normalise precarity so much."

"The historical present makes itself available to you when there's a crisis in the reproduction of life."

"Everyone invests in objects that organise the relation of fantasy to how they live...the working class's are in the present, the middle class's are in the future."

"In a crisis time, many people's sense of the precariousness of the present becomes present to them."

"Our genres of confidence in the world are shattering."

To criticise such meaningless, generalised drivel, to point out the lack of well-defined terms, the lack of logical reasoning, and the lack of verifiable statements based upon hard evidence, would be to potentially crush this delicate form of performance art in its nascent stage. Even in a time of such 'precarity', we must find more money to fund the lifestyle of these modern sages, and reward them with ever greater slices of publicly-funded airtime.

Snow and horseshoe vortices

With snow blanketing much of Western Europe at the moment, here's a chance to do some aerodynamic investigation in the field.

Somewhat counter-intuitvely, it turns out that under certain conditions snow fails to accumulate on the windward side of a tree. The reason for this is that the snow at the base of the tree is scooped out by a horseshoe vortex.

A high-pressure stagnation point forms on the windward side of the tree, and this creates an adverse pressure gradient for the flow approaching the tree. The adverse pressure gradient causes the boundary layer of the flow across the ground to detach and roll-up into a vortex. (The photo and first diagram here are taken from Internal flow: concepts and applications, p117, Greitzer, Tan, and Graf, 2004). The vortex is then bent down the sides of the tree, where it also scoops out some snow.

Similar vortices can be found on cars or aircraft at the junctions between a wing-section and the endplate or fuselage.

The connection between Formula 1 and Dark Energy

Perhaps to the surprise of many aerodynamicists, one of the concepts deeply familiar to them, may actually explain the existence of dark energy.

This ominous form of energy corresponds to an extra source term in the cosmological version of the Einstein field equations, and is commonly held to be responsible for the accelerating expansion of the universe.

The connection with aerodynamics lies with a concept used to represent turbulent flow, called Reynolds Averaging. Despite the supercomputer power available in Formula 1, it remains impractical to solve the exact Navier-Stokes equations for a turbulent flow. Instead, the velocity and pressure fields are split into the sum of a mean field and a fluctuating component, and the Reynolds-Averaged Navier-Stokes equations are solved to calculate the mean fields.

However, the process of taking the average of the Navier-Stokes equations generates an extra term, which is interpreted as an extra source of stress. One thinks of the mean field as having to do work against the extra stresses created by turbulent eddies, as well as the viscous stresses already inherent in the fluid.

Thus, whilst the Navier-Stokes equations for a steady flow are as follows:







The Reynolds-Averaged equations pick up an extra term on the right-hand side:







Now, as cosmologist George Ellis and his colleagues explain, whilst the exact Einstein equations hold at the local scale:



Once one averages the matter-energy and geometry over galactic scales, the Einstein equations pick up an extra term:



Sound familiar? As Ellis et al comment, this "is the effective matter source term representing the effect of averaging out smaller scale structures."

Whether this type of effect can explain the quantitative cosmological data remains to be seen, but perhaps aerodynamicists have something to offer the cosmological community here.

Wastegate-blown diffusers

Whilst the FIA have made extensive efforts to prohibit the use of exhaust-blown diffusers in Formula 1 from 2012 onwards, there appears to be no such proscription on the use of compressed air from the inlet manifold of an engine. Formula 1's engine formula changes to a 1.6 litre turbo-charged V6 in 2014, and the turbine in such an engine is constantly generating compressed air. The inlet manifold of a turbo engine has a blow-off valve, specifically designed to release pressure when the driver lifts off the throttle or the throttle is closed. Thus, the blow-off valve could be vented down to the sides of the diffuser, providing vital extra downforce when a driver comes off the throttle turning into a corner.

In terms of the legality of such a system, there is already a clear precedent. As pointed out in Giorgio Piola's Formula 1 Technical Analysis 2010/2011, the very first exhaust-blown diffuser, the Renault RE40 of 1983, had several outlets blowing each lateral channel of the diffuser; in Piola's diagram (p15), three came from the exhaust, but one came from the turbo wastegate, (in fact, in pictures featured on Craig Scarborough's site, there are only two outlets from the exhaust, and one from the wastegate).

Piola points out that the legality of the system was protested by Brabham at the 1983 Detroit Grand Prix, but the protest was rejected both in situ, and at a subsequent tribunal on 26th July. Hence, whilst the FIA might be able to regulate the position of the exhaust outlets, and the off-throttle pumping effect of the engine, the turbo wastegate could conceivably be used as an independent blowing device in 2014.

McLaren's floor tiles

The BBC recently broadcast a documentary on McLaren's new supercar, the MP4-12C. In the opening minutes of the programme, we follow Ron Dennis around the immaculate McLaren Technology Centre. As Ron strides across the lakefront atrium, he points out a broken floor tile, and expresses his annoyance: "The reality is, when it's changed, it'll be imperfection, because the colour won't match. Tiles come in batches. You can see this one here's been changed, [pointing to a darker tile.] Doesn't that bug you? It bugs me. Big time."

In fact, rather than tiles from different batches being of a different hue, in this case the reason a new tile stands out is probably that the old ones have been subjected to the daylight for a period of time, and due to the slow photodissociation of the pigments inside, will gradually be growing lighter in colour. Hence, a new tile looks darker simply because it's been exposed to daylight for a shorter period of time.

There is, then, a possible means by which McLaren can mitigate this chromo-tessellatory problem: Purchase a sufficient number of spare tiles at the outset, and then allocate a backroom at the MTC for the purpose of exposing these backup tiles to the correct diurnally-averaged spectrum and intensity of artificial sunlight. When a frontline ('customer-facing') tile suffers a fracture, the replacement will have endured the same amount of photodissociation, and will be indistinguishable in colour from its two-dimensional siblings. Problem solved.

Autocourse 2011-2012

This year's Autocourse is printed on golf-leaf infused paper, using inks derived from the pituitary gland of the Himalayan gazelle.

At least, that's the only justification one can imagine for a price-tag of £50.

There was a time when one could look forward to the stunning photography in Autocourse each year, but those days are long gone. This year's edition contains only one memorable image, a two-page spread of Lewis Hamilton and Sebastien Vettel, wheel-to-wheel into Turn 3 at the Hungaroring, Hamilton's outside wheels skirting the grass-verge. Unfortunately, most people will have already seen this image, and the photography elsewhere never rises above the mediocre.

In fact, the quality of the photographic reproduction in Autocourse has become remarkably dark, virtually every image dominated by the sheer quantity of black ink. As an indication of this, it's almost impossible to find an image of a car, taken from the front, in which the undernose splitter can actually be discerned. By way of contrast (excuse the pun), if you happen to have the £4.40 Autosport Formula 1 review at hand, compare the picture on p32-33, taken from Ste Devote at Monaco, with the picture on p153 of Autocourse, taken from exactly the same vantage point. The difference is almost literally night and day.

It's difficult to know whether this is determined by the combination of inks and glossy paper used by Autocourse, or whether there's some artistic motivation behind it. There's almost a photophobic, crepuscular mood running through the annual: an article on Pirelli opens with a two-page spread of Hamilton and Webber in the gloaming at Korea; the team-by-team review begins with a two-page spread of the F1 paddock in semi-darkness; the race reports are prefaced with a two-page spread of a Williams passing through a silhouetted Eau Rouge; there's a two-page spread of Lewis Hamilton beneath leaden skies at the Nurburgring; there's a two-page spread of Singapore, in the darkness; and there's a two-page spread of Jenson celebrating his Japanese victory...in the darkness. It's like a book directed by David Fincher.

Formula 1 should be bright and colourful. Autocourse makes it look like an activity which takes place at 7pm on a damp October day in Macclesfield.

So do you get anything for your £50? Well, yes, you get Mark Hughes's team-by-team analysis, which is reliably superb. Mark, of course, also does something similar in Autosport's Formula 1 review, but the Autocourse version is more detailed in places, and contains extended explanation from each team's technical director. Paddy Lowe and Pat Fry, in particular, are fascinating this year as they explain where things went awry.

So there's something good here, but not £50-worth.

Red Bull and Immersed Boundary Methods

Autosport's recent 2011 Formula 1 review pointed out that whilst Red Bull were the first team to appear with exhausts blowing the outer extremities of the diffuser, "others, notably Renault and Ferrari, had tried the layout in their tunnels before the Red Bull appeared and couldn't make it work, and Newey later confirmed that it actually took months of simulation work to maximise."

So what is it that Red Bull were able to do that other teams weren't? Was it mere persistence in the wind-tunnel with a flow regime that transpired to be extremely sensitive to the exact position and geometry of the exhaust outlet? Or were Red Bull able to apply some form of computer simulation not currently utilised by other teams?

Perhaps the former is the most likely answer, but let's pursue the alternative explanation, and see if we can join up the dots. And let's start with the fact that Red Bull use Ansys Fluent as their CFD package. In this promotional video from late 2010, it's acknowledged that Red Bull use Fluent to model their exhaust flow, (although this obviously doesn't entail that it's their only simulation tool for doing so).

Speaking recently about the High Performance Computing solutions provided by Ansys, Nathan Sykes, CFD Team Leader at Red Bull Racing, pointed out that "To retain freedom to innovate and adapt the car quickly, we rely on a robust modeling process. This puts new designs on the track quickly. To accomplish our goal, we continually need to leverage technologies that help us introduce and evaluate new ideas. With a significant reduction in process times over the last three years, ANSYS HPC solutions have continued to be the tool of choice for us."

Now, the normal aerodynamic optimisation cycle involves shaping a part in CAD, importing it into CFD, meshing it in CFD, running the CFD solver, and then post-processing the results. Meshing, in particular, can be very time-consuming. There is, however, a means of short-circuiting the cycle, called the Immersed Boundary Method, and in an environment such as Formula 1, where aerodynamic turnover is paramount, any team able to successfully implement this method could gain a significant advantage.

Immersed Boundary Methods provide a means for dealing with geometries which may be complex, or in a state of motion. They enable one to mimic the effect that an appendage has on the fluid flow in terms of something called a 'body force'. For example, if a fixed solid object is introduced into a region previously occupied by fluid flow, then the no-slip boundary condition must be imposed on the new surface, (i.e., the velocity there must be zero). In effect, this requires the application of a force which reduces the pre-existing velocity to zero. To calculate the necessary body force, one could in principle insert the necessary acceleration into the (Reynolds-Averaged) Navier-Stokes equations, as below, with u_desired=0 in this case:



Coincidentally, Ansys Fluent 12.0, released in 2009, has an Immersed Boundary module, developed with Cascade Technologies Inc. This is what Ansys said at the time:

A conventional fluid dynamics simulation starts with the transfer of CAD data to a grid-generation package, in which a surface mesh and then a volume mesh are generated before the simulation can be set up and the solution run. The effort and time required for such pre-processing tasks can be significant. For example, in cases with complex or dirty geometry that require CAD cleanup, this part of the process may take 50 percent to 90 percent of the total time required for the simulation. The Immersed Boundary module addresses such issues by providing a rapid, automated, preliminary design approach.

Fluid flow simulations using the Immersed Boundary module for ANSYS FLUENT 12.0 software start with the surface data of the simulation geometry in the STL file format, which is commonly used in rapid prototyping and computer-aided manufacturing. This CAD geometry does not need to be clean, does not require smooth surfaces or geometry connectivity, and may contain overlapping surfaces, small holes and even missing parts. The simulation geometry is meshed automatically. Mesh refinement also is carried out automatically after specifying the desired resolution on the boundaries, ensuring the accuracy required for preliminary design evaluation. Using the immersed boundary meshing technique greatly reduces the amount of time spent preparing the geometry for meshing and creating the mesh.

At first sight, Immersed Boundary Methods do not appear to be available in Star-CCM+, one of Fluent's main competitors. Star-CCM+ does, however, provide a Surface Wrapper, a type of shrink-wrapper, which fixes gaps and overlaps in complex CAD geometries. Nevertheless, in Star-CCM+ it appears to be necessary to create a body-fitted mesh: a surface mesh must be created on the surface imported from CAD, and then a volume mesh is grown outwards from the surface mesh.

Immersed Boundary Methods have become increasingly popular over the past decade, and knowledge of such techniques will have been carried into the world of Formula 1 by many recent PhDs. Nevertheless, it's interesting to speculate whether Red Bull have stolen another march on the opposition here...