Simulating a lap

In F1 world anything that can help you make the car better is welcome. This time we will talk about software simulators and in particular, showcase the one from Ansible Design. It's called AeroLap and is able to simulate a whole lap given certain car parameters and even take environmental factors into account. This entire article would have not been possible without the kind cooperation from the people at Ansible Design, Woking, UK.
This software has been used successfully for years throughout all kinds of motorsport divisions, including existing F1 customers.

AEROLAP

How it works

Using a complex, multi-layered model with many non-linear components, and performing hundreds of thousands of calculations for a run AeroLap can provide more realistic and accurate results than other methods.
The underlying calculation method is to discretise a given 3D path into small segments. For each segment the maximum thrust is applied to the car, according to the authority of the engine or braking system and limited by the grip available, driver behaviour and other forces on the car e.g. aero or gravity. A pseudo steady state solution is found for the sprung mass position and the solver focus moves to another segment. Segments are solved in the most efficient order, which is often not sequentially. When all segments have been solved the results can be presented as a continuous time history.

How the teams are using it

• Decide race engineering strategy before going to the track.
• Prepare your setups in advance for changes in track layout, or for going to a new track.
• Make key design decisions before committing to building a prototype.
• Choose gear ratios based on their effect on laptime, automatically taking account of many factors that are not considered when using ratio charts or spreadsheet modelling such as engine performance, track gradients, ambient wind speed.
• Compare different engine torque/power curves, both in terms of predicted lap time and by plotting the engine torque or power actually being used throughout the lap.
• Run a variety of aerodynamic trims and look at lift/drag trade-offs.
• Predict ride heights and alter the suspension setup so that you are getting the best out of the car's aerodynamics.
• Examine the effect of different fuel loads on performance for pit strategy.
• Setup your suspension to get the best from the tires.
• Gain a better understanding of what affects your car's performance and why.

They say picture is worth a thousand words, so instead of describing all parameters that can be modified I will feature them in a series of screenshots. The sample data we have available is for Le Mans car and track layout, but assume that track data can be modified to match precisely each of the F1 tracks, just as well as car parameters. Let's dive in and don't be scared by the amount of numbers - these are all vital parts of car setup. The article itself could always be updated to include even more screens.

Parameters
Define and setup a model of car - you can choose parameters for:

1.  Aerodynamics - reference frontal area, front and rear downforce, wind tunnel offsets, etc. This data can be also generated from AeroContour software, which is going to create the aero maps. Example:
   
   This is the one displaying downforce related to front and rear ride height, here's also one showing the drag:
   
2. Chassis
   Defining the physical dimensions of the car, masses - front, rear and even mass on the grid (assuming driver plus fuel)

   

   Mass

   

   Dimension

3. Suspension
   
   
4. Tires
   
   
   This includes data for all four tires
5. Gearbox
6. Environment factors
   
   
7. Engine data
   
   
8. Track data
   

Finally, as soon as we have all the input parameters set, we can hit the big Play button, which activates the solver and interactively the little yellow circle (the car) moves around the track. On a moderate normal desktop PC the simulation took around 8 seconds and the result looks like this: 

Other charts and graphs that are useful to data engineers are various parameters which progress as the lap advances, such as Speed vs. Lap or Torque / Engine RPM vs. Lap.
Here's an example:

On this final tab where you see the results of the simulation, there are multiple channels to select from, i.e. you can overlay the Speed vs. Aero drag, in our case labeled as Cd (coefficient of drag):

Quite obviously, the drag increases as the speed goes up. In the same manner multiple parameters can be displayed, derived from the base suspension, chassis, tires, aerodynamics, etc. These results are also available in table format as data values, so that you can export them and pass the output to another chart-drawing software. 

Finally, we would like to have a look at our results and revisit the strategy for the race. Back to the suspension module gives us the option to change the ride height from 65 mm to another value, I will select 80 and then re-run the simulation. The results are clear from this simple change: 

We lost about 0.7 seconds for the whole lap, and this is a clear indicator that increased ride height is perhaps not the most optimal strategy. In the same fashion you can tune and play with all available parameters, check the results and decide what to do. Again, this gives precious insight to race engineers, designers and aero people to make early predictions on what direction to follow when building / modifying a car, as well as create and adjust racing strategies. 
Aerolap, as a mature software, has a lot more to offer, for example integration with software from the same breed, such as AeroSusp or AeroContour to literally any kind of motorsport division. 

Thanks for attending, questions are always welcome. 

Inside wind tunnels

In Formula 1 world there are three types of testing validation for new parts: CFD, on the track (free practices or tests) and Wind Tunnel installations.
Lot has been said about the latter, so I'm not going into details about rolling floors or boundary layer suction, but instead I'm going to focus on what and how specifically is being measured in a Wind tunnel and why is that of paramount importance for F1 teams.

One of them has recently been all over the specialized news feeds, namely Ferrari, with their Wind Tunnel struggles, failing to produce correct correlation between tested parts and what's actually being measured on the track as results.
Various sources have been suggesting that Ferrari F1 Team will shut the tunnel down and make re-calibration, system checks, improvements, even calling external consultants, presumably from aerospace industry to check what's wrong. Just how much of all these is true is unknown to the general public, but talks about new wind tunnel construction have also appeared. It is perhaps worth saying that this is large investment and its rough estimated cost is about 40 to 50 million US dollars, besides it takes a lot of time for pure construction and realization.
UPDATE [20.Dec.2012]: Stefano Domenicali confirmed that Ferrari's wind tunnel will be undergoing major overhaul, will remain closed until August and Ferrari's 2013 car will be developed exclusively in TMG facility - see details below.

Apart from the economic outlook, teams are allowed to test with scaled model, up to 60% of the real size, and use speed of up to 50 m/s, which is 180 km/h max or 111.8 mp/h if you prefer imperial units.

Since the model parts do not represent the real world car size, Reynolds number is, for example, used to make coefficient correlation between the 60% model parts and 100% model. However, it is important what the source data shows.

Below you may find a sample spreadsheet with totally bogus and unrelated data, which is there to simply demonstrate the various parameters being measured in a wind tunnel session. Time spent inside the installation is also precious, as teams are having certain time frames allowed.



 Let's break down the data sheet into details:

1. Cell B holds the value for Lift, in our case there is downforce generated, hence the negative sign. It's usually being measured in Nm, but it may vary in different wind tunnels implementation (Kilograms are often seen, too). 
2. Next we have Drag, which is pretty obvious.
3. L:D is lift-to-drag ratio - one of the most used measures for aerodynamic efficiency - sure, you can add more downforce via Angle of attack settings, but this comes at the expense of added drag, too, so balance is important. 
4. Drag power - this is the consumed horse power, the power required to overcome aerodynamic drag.
   Note: this is a velocity-sensitive parameter, and the formula is simple:
   DRAG HP = ( Drag coefficient (0.9 or 1 for F1 car) * Frontal Area in square meters (assume 1.35) * current velocity (200 km/h = 55 m/s) cubed ) / air density (1225 kg/m³) = ~ 124 HP to overcome aero drag. The same formula gives about 380 HP at 250 km/h, etc.
5. The next three columns, FY, FX and FZ are moments, measured as distribution of aerodynamic forces around Center of gravity, aligned with the three axes:

   

   Copyright: F1 Framework

6. Next, in columns I and J we have vertical loads on the front and the rear, which is very important parameter measured from suspension point of view. While measures here differ, these are usually Newton meters, in this sample sheet the values are in kilograms.

These are some of the most common parameters that teams are measuring in a wind tunnel. Apart from those numbers, more can be crunched as a mathematical representation of the measurements taken, namely calculating coefficients. All of those numbers and their values are carrying certain amount of knowledge in regards to how your car will supposedly behave and that's why it is very important that the output is correct, as this decides what configuration and parts to put on the car.

TOYOTA MOTORSPORT 

The next chunk of details goes directly into the heart of Toyota Motorsport GmbH wind tunnel facility in Cologne. F1 fans have heard a lot about it, especially when it comes to Ferrari, but first, I, with "no wax", like to thank their staff for being gracious enough to release those images and data for the public and being patient enough to explain everything. Below you may find some exclusive images from the tunnel.

Outside look of the tunnel's diffuser section

The instrumentation of this state-of-art facility consists of two wind tunnels : one full size and one 60% scales.
Both wind tunnels use a continuous steel belt rolling road which has a maximum speed of 70 m/s. What can really describe those installations is accuracy and high quality - 512 pressure measurement channels are available. The tunnels are also equipped with Particle Image Velocimetry system (PIV) - an optical method of flow visualization used to obtain local flow velocities. The PIV system is usually used to validate CFD predictions and thus better calibrate the setup.
One of the advantages of such PIV system is that its preparation time is almost zero, due to the seeding technology used. That means that the local air is filled with tracer particles and there's no cleanup needed after that. During the process of measurement, cameras are used to obtain images and samples, which are then processed by computer software.
A laser is used to illuminate the flow field around the car’s front wheel to take particle image velocimetry (PIV) measurements (see below).

One of the main advantages of this method, just as well as the PSP method, is that it's non-intrusive, as opposed to the traditional pressure taps.
"Many of today’s motorsports cars are based on existing, commercially-available cars." Frank Michaux, a researcher at TMG, reveals.

"If researchers can identify a way to reduce drag on a motorsports car, it’s reasonable to assume that this information also may apply to future versions of a normal road car." Frank continues: "We need to deliver data quickly. If you see that you are not capturing the flow correctly, then you need to adjust your CFD methodology until you get it right".

After gathering the raw data from the PIV measurements of the “separation point” on the front tires, engineers post-process the data using Tecplot software, which allowes them to see and measure the exact position of separation. Each of Toyota’s PIV measurements consist of 300 datasets, with each dataset containing two images taken 10–20 microseconds apart.

The Tecplot software package itself is widely recognized and used throughout the industry.

INTEGRATION POINT - PIV & CFD

During the 2009 season, F1 engineers wanted to carefully study the flow wake behind the front wheels. Since this is critical part of overall car performance, the goal was to push this flow as outboard as possible. Engineers have realized that they need precise back-to-back correlation, and here's a direct comparison between CFG and PIV images: 

In order to get to those precise points, the CFD methodology has to be optimized, and here's a real case:

The next thing about Toyota Motorsport GmbH is its Continuous Motion System.

In CMS mode, a user-defined programme of ride height, yaw, roll, steer and individual pre-load changes provides continuous motion on a predefined trajectory while the HSDA system is continuously acquiring data at high frequency.
This allows realistic road or track analysis and increasing the amount of useful data from each individual test compared to standard motion and acquisition systems.
The typical "Wind-On" time is reduced by 70 to 100%  with CMS, which allows more time to be dedicated to, for example, changing parts. This Wind-On time is extremely precious for F1 teams, which we all know run under certain restrictions when it comes to wind tunnel time. 

Below you may find some exclusive images from inside the tunnel (full sizes available upon click): 

Very good representation of scaled model compared to a man

Toyota TS030 early prototype version

The control and monitoring room

Testing preparation - Toyota TF110
Front wing flap angle at 27 degrees

Surveillance and monitoring  

Glad you have reached this point - I assume you were very interested or your scroll button was stuck :)
As usual, comments and questions are welcome.

Young drivers test at Yas Marina 2012 and its importance to 2013 season

"Hello, World!"

This is one of the very first strings that young programmers are printing out on the screen when starting with software development. Here, however, we shall talk about young drivers test in Formula 1 which has taken place in Abu Dhabi, on the most expensive track facility anywhere in the world - Yas Marina. Many testing permutations, tire compounds and interesting testing tools have been used, and we have even seen one driver testing two different cars!
Overall, the feedback from the drivers was very positive, let’s take Esteban Gutiérrez for example:

“The morning session was very interesting for me because we tested a lot of different things, and I hope I gave my most precise feedback to the engineers. After being in the car so recently in India, of course, I feel a lot more confident in handling all the system like KERS and DRS. In the morning session I used only hard tyres, but in the afternoon I certainly enjoyed running the medium as well as the soft compound. The last sector of the track I find a bit tricky, especially turn 20. I don’t have the confidence yet to push harder there.”

The combined time results from the three days look like this:



Later down in the article you can find more interesting stats about this event.

And although this is testing for the young drivers, all teams have used the chance to evaluate certain developments or just to gather aerodynamic data.
Let’s get down into details about the interesting stuff we have observed on the track.
Most of the teams and the drivers told us not to look too much into the times, but it was obvious that top 3 drivers were very quick and their scores were almost half a second better than the rest of the field.

A typical example of a daily session program would look like this:

• Morning Session: Aerodynamic testing and DDRS iterations. 
• Afternoon Session: Front Drum testing and tyre assessment Programme. 
• Total number of laps: 86 
• Best lap time: 1:42:677 
• Tyres used: Two sets of hard, two sets of medium and two sets of soft compound tyres.

DRAG REDUCTION DEVICE (DRD)

What can really summarize the testing efforts was the extensive usage of pipes protruding from underneath the engine cover or similar places, which were usually ending below the underside of the rear wing’s main plane. (Credit for the name goes mainly to my fellow blogger and tech analyst Matt Somerfield)

This type of the device appears to be initially tried by Lotus, and it looks like this:

While Lotus’ implementation is bit different than the rest, the principle is believed to be the same: passive blowing certain parts of the rear of the car, i.e. no human interaction is required. Note about next year regulations: DDRS implementations such as the one found in Mercedes car will be prohibited, hence the teams are looking for more efficient and legal solutions.

The next team that has tried similar approach was Mercedes, and the rest followed soon - Toro Rosso had interesting implementation as well, Red Bull and Sauber. Details:

Red Bull

It is immediately obvious that Red Bull may be looking for different approach, as the pipe is directly connected to the rear wing with no obvious open slots. Extensive flow visualization has also been added, something that RBR have demonstrated in almost any free practice so far.

Sauber

The solution from the Swiss team is more closer to Mercedes’ initial implementation. Generally, those types of devices are aiming to create low-pressure area at the underside of the main plane of the rear wing, where, essentially, the downforce is “born”.

Sauber did not have the typical inlets that would feed such passive system with air, though additional pipes have been spotted around the nose cone.

Toro Rosso

From the same bull breed, the younger Reds tested a larger version of the so called “monkey seat” - relatively cheap way to add rear downforce via such device which resembles smaller, scaled down rear wing. There are variations across different teams’ implementations, but STR7 features the largest of them, as of yet. The Italian team have also tried something which looks like a DRD attempt, however, with no clear evidence of ducting at this point. Certain analysts have assumed that this is a result of James Key’s introduction to the team as Technical Director, replacing Giorgio Ascanelli.

What stands above the engine air inlet is called Pitot static tube - an instrument measuring fluid flow velocity.

On the next day, the team has tried another variation of the Monkey seat which was lot more taller than the previous installment, and it was somewhat resembling a DRD, though strict evidence of holes were not immediately obvious - perhaps the team wanted to evaluate just the amount of drag coming from such option:

Image credit: AMuS

AERO RAKE

Literally every team had his chance to run various types of test rigs, mostly known as aero rake.
The aero rake itself could be used for measuring air speed, angle flow, pressure (Pitot-Static probe) and even temperature.

What is really a Pitot tube?

It's a thin tube that has two holes - the front hole is located to face the airstream for measuring the stagnation pressure. For incompressible flow (where the material density is constant) it is a sum of the dynamic pressure and static pressure. The side hole measures the static pressure and the difference between these two is dynamic pressure, which can be used to calculate fluid flow and speed, in our case that's the air. Some of the teams are using a variation which is called “Kiel probe”.

Let’s have a look at teams’ applications:

 Red Bull have been using similar rake for some time, notably this one, used in Canada Free Practice as well:

This is what Caterham team calls “Transition Vortex Rake”. The team also had infrared camera to monitor tires.

Copyright: Caterham F1 Team

Next we have the high tech team of Mclaren:

Notice they are running two applications - one behind front right tire and one behind the Monkey seat, which has the ability to move up and down.

On the second day Mclaren ran a completely different front wing, which bears some resemblance to the one Lotus is using. Here’s a direct comparison - the new one is on top:

The new wing now features two vertical flow conditioners, a la Lotus, which effectively removes the upper R cascade elements (yellow arrow below), which tells us that Mclaren are willing to sacrifice some front downforce. Next we see that the new wing has no outer blade near to the endplate, and in general looks simpler than the old one.
The underside of the main plane (old vortex curvatures) features more nicely curved forms as opposed to the old shapes, which were rather triangular.

Curiously, this test has apparently proved successful for the new wing, which was subsequently raced in Austin and Lewis Hamilton won the race!

Mclaren also had the usual sensor bulge on the nose (inset right) plus pale purple flow-viz on the new front wing (left hand side) – this type of color is less visible on the track (to hide details from rival teams), but it is excellent displayed under ultraviolet light.

Lotus revered to their old exhaust style for the final third day:

---

BOTTOM LINE

• Most of the teams are definitely looking at 2013 season and usage of passive devices to gain rear downforce. 
• Teams did not lose time and various ways to collect data, such as flow viz and aero rake, have been used.
• The test featured quite good reliability except for one minor incident (oil leak for Caterham).
• Kevin Magnussen set the best time on the first day, before noon.

STATS

Note: The bars are interactive, hover the mouse over any of them to reveal the actual value.

All images are linked from F1 Zoom (unless otherwise noted) and are posted under the Fair Use Doctrine for purely educational and comment purposes. 

PSP in F1

Hello and thanks for tuning in on this frequency again.

The following article comes exclusively with the help of the kind people from ISSI - Innovative Scientific Solutions Incorporated. Their commercial site is located here.

We are not going to talk about PlayStation Portable, as the headline hints, but for Pressure Sensitive Paint (henceforth abbreviated PSP) - a method which stands between traditional F1 development paths - wind tunnels and CFD (but not a replacement for any of them). This is something that has been in use for quite some time, especially when it comes to NASA and airplanes.

WHAT IS PRESSURE SENSITIVE PAINT

In short, this paint-like coating fluoresces under a specific illumination wavelength of incident light and the fluorescent response is a function of the external air pressure being applied locally to its surface.
A typical PSP is consists of luminescent molecule and a polymer binder which must be permeable to oxygen.

There has been some use and some interest by certain F1 teams in using PSP in their own tunnel testing. 30m/s is typically the lower limit of PSP due to smaller pressure gradients below that speed. Most use PSP to validate CFD results or vice versa.

Imagine that in the end you could receive the same pressure distribution picture as you normally get from a CFD simulation run:

Image credit:  http://www.psp-tsp.com/

WHY IS PSP ADVANTAGEOUS 

A key advantage to traditional experimental techniques like pressure taps and transducers:

• cost savings 
• not limited by model geometry
• provides much higher spatial resolution than traditional methods

Essentially you'll have a "pressure tap" at every pixel of your camera. So if you are using a 1-megapixel camera, that's like having 1 million pressure taps on the surface. Once the experiment is set up, many runs at various conditions can be made rather quickly by comparison to CFD and data turnaround is much quicker as it can be processed on site with some knowledge of the test conditions and local pressure taps on the model if available.
Paint formulations have also been developed recently which allow for unsteady measurements of pressure using a high speed camera. Measurements can be made upwards of 10 kHz on the surface.

THE PROCESS

The typical process could be described with the following simple steps:

1. Painting: Whatever the testing object might be, the usual paint gun or airbrush could be used. 
2. Excitation: The molecules inside the paint have to be excited, so there is a light illumination source applied to the painted surface.
3. Data gathering: The CCD camera kicks in collecting the fluorescent response from the illuminated surface
4. Data visualization: Different software packages could be used to visualize what's already being recorded and thus used for analysis of pressure gradients. 

Two immediate questions have arisen, fortunately Steve Palluconi, a research engineer, was available for this short interview: 

Question: Due to its (PSP's) spraying technique - would that be too much disturbance of boundary layer or not at all? Negligible, maybe?
Answer: Generally the layer thickness is 20-30 microns and is very smooth. Negligible for these types of tests. Pressure taps are more invasive as we’ve actually seen flow separation caused by them.

Question: Are there any estimates on cost? For example, would it be too expensive to implement or improper, for example, due to model scales (in F1 - up to 60% of the real car size)
Answer: Costs depend on the scope of the test and size of the model. Large models like the one referenced would usually be imaged with a multi-camera system. Smaller models can be imaged with a single camera. We've done testing on some large aircraft models.

Should you have more in-depth and scientific questions you can always contact Steve through their web site.

F1 aero glossary

The idea of that article is to be a reference point for the most used aerodynamic terms in Formula 1.
The list doesn't pretend to be exhaustive or fully descriptive on certain topics, such as CFD, but for now I'd prefer the simpler variant, listed alphabetically for easier navigation. Additions and comments are appreciated , but at the same time I will assume that you know the basics, for example the fact that there are four forces that act on a car: lift, weight, thrust, and drag.

The format is simple:

• TERM
• Explanation
• Illustrated picture (almost all have larger sizes)

Shift into gear!

AIRFOIL
[Explanation] In British English you can also find the term as "Aerofoil", but generally this is a transverse cross-section of a wing. This is how the term is named in all aerospace sources, but in motorsport that's just another word for wing or its shape.

[Picture] To follow below, when explaining Angle of attack

ANGLE OF ATTACK
[Explanation]
This is the angle between airfoil's chord line and the crosswind airflow, regardless of wing's direction.

[Picture]

image credit: http://wikipedia.org

ASPECT RATIO
[Explanation]  The ratio of the length of wings to their width is called aspect ratio. A high aspect ratio indicates long, narrow wings. A low aspect ratio indicates short, wide wings.

In short, a simple formula to present it mathematically: 

Aspect ratio = wing length / wing width

[Picture] 

Image credit: http://NASA.gov

BARGEBOARD
[Explanation]
Bodywork piece on an open-wheel race car, which is usually situated between the front wheels and the sidepod. They, the bargeboards, are usually created with trapezoid profile, and their main task is to redirect turbulent air (flow conditioners), from the wake of the front wing, tires and suspension.

Another function of bargeboards is to serve as vortex generators, for example, creating and directing a quite fast vortex around the sidepods.

[Picture] 

Original concept: deus1066, Model remix: F1 Framework

BERNOULLI'S PRINCIPLE

[Explanation] 

In 1738 the Swiss mathematician Daniel Bernoulli publishes in his book, Hydrodynamica, the principle stating that an increase in a fluid's speed occurs simultaneously with accompanying decrease in pressure or decrease in fluid's potential energy.
Here we see very close relations and roots with the Conservation of Energy principle, as well as Newton's 2nd law. 

BOUNDARY LAYER
[Explanation]
When an object moves through a fluid or gas the molecules of the fluid near the object are disturbed and aerodynamic forces are created, whose magnitude is dependent on fluid's viscosity and its elasticity.
The former is very important, as the molecules right next to the surface of the object are sticking to it. Then, there's a collision between molecules sticking to the surface and those above it - this creates a tiny layer with 0 to very small velocity which is called Boundary layer.
Boundary layers can be Laminar or Turbulent, which are covered below.

[Picture]

Image credit: NASA.gov

CAMBER (ANGLE)
[Explanation]
Misdirection such as "camber is the top surface of a wing" do exists, but in fact if we look previously at Angle of Attack's picture, we will notice that one of the surfaces is just more curved than the other - than it's said that the airfoil has camber, while the camber angle is the difference between the chord line (red) and camber line (blue).

COMPUTATIONAL FLUID DYNAMICS (CFD)
[Explanation]
CFD is a leaf on the large tree of fluid mechanics which uses numerical and computational methods to solve issues arising during fluid flow.
It is important to note that typical CFD simulation offers approximations and assumptions by solving Navier–Stokes equations, which define any single-phase fluid flow. Recently there is a lot of interest in two or multiphase models.
F1 teams would usually use CFD along with wind tunnel testing to correlate the produced data and produce parts with greater confidence, having done simulations prior to actual fabrication and production. Such simulations often require large computing power in order to complete as fast as possible.

Generally, a CFD task usually consists of three main stages:

• Pre-processing - where geometry is defined, the total occupational volume of the fluid is divided into cells - mesh creation, as well as physical models and boundary conditions;
• Solving - the actual process of  iteratively solving the conditions of each cell;
• Post-processing - the stage where the results for each calculations are being analyzed and then presented in a readable form, usually like the picture below.
  In most of the cases the red color zones will mean high pressure, while the blue is the opposite - low pressure regions. 

[Picture]

ANSYS Fluent pressure gradients in polyhedral mesh

[Picture]

Image courtesy: Voxdale
In this particular case, the colors stand for velocity - red is high, blue is low.

DOWNWASH
[Explanation]
The downwash effect is simply an air which is forced down - due to wing trailing edge or due to the shape of the body in general. In case of downforce inducing airfoil, the downwash occurs in front of the wing.

Video with downwash effect on a finite wing can be seen below, at Wake section.

[Picture]

Original concept: deus1066, Model remix: F1 Framework

END PLATE
[Explanation]
In order to overcome the problem of turbulence created between the front wheels and the front wings, end plates have been introduced (blue color on the picture below). During the years they had different shapes, but have been used to redirect air away from the tires, and also as pressure equalizers (at rear wing), having in mind the usual wingtip vortices.

[Picture]

Original concept: deus1066, Model remix: F1 Framework

FLAP
[Explanation]
The front wing of F1 car consists of end plates, center section, cascade elements and main flap, highlighted in blue on the picture below. Generally, there's a slot gap between each of the elements, in order to keep the air as attached as possible, thus prevent stall and flow separation. This flap is the element that determines the angle of attack of the front wing, it is adjustable, and therefore it is very important part.

[Picture]

Original concept: deus1066, Model remix: F1 Framework

GURNEY FLAP (WICKERBILL)
[Explanation]
That term originates back in 1970's where American Dan Gurney was fixing this small device at the trailing edges of the wings on racing cars. This is really an effective way to increase the downforce of a wing at the expense of small drag induced. Different researches are quoting different numbers, but let's throw some average numbers and give a ratio of 8% more downforce vs. 3% increase in drag.
What is actually little known as fact is that Gurney flap increases lift by changing the Kutta condition (related to sharp trailing edges), so the wake behind the flap are two counter-rotating vortices (also very typical to diffuser lateral edges, where Gurney flaps are present, too).

[Picture]

OR

Original concept: deus1066, Model remix: F1 Framework

LAMINAR FLOW
[Explanation]
Laminar flow is sometimes also known as streamline flow, occurs when fluid flows in a parallel uninterrupted layers. The main characteristics of laminar flow are its smoothness, the lack of swirls or vortex formations (as much as possible), steady velocity and hence stable pressure gradients.
Few more lines below we are going to talk about Reynolds number, but generally laminar flow is characterized with low Reynolds number (Re).

[Picture]

LIFT TO DRAG RATIO
[Explanation]
Most commonly you will find this term abbreviated as L/D ratio or simply Ld - is the amount of lift (or downforce) generated by a wing or vehicle, divided by the drag it creates by moving through the air.
That ratio has lots of components that build it, but for now we will skip the math and the formulas, and will conclude that in F1 engineers are always trying to achieve higher downforce at lower drag coefficients, which is usually a result of a balancing act - in either setup or design stage.


PITCH SENSITIVITY
[Explanation]
While in motion, certain aerodynamic forces act on a race car. The magnitude of those forces is commonly known as pitch movements, and the ability of the car to cope with them is know as pitch sensitivity. That ability is directly related to the way the car feels and handles, for example sudden and excessive diving nose when braking. More can be seen below at Yaw paragraph.


REYNOLDS NUMBER
[Explanation]
Reynolds number can be frequently seen when solving fluid dynamic issues, just as well as characterize different flow modes, such as laminar or turbulent flow. It is generally a ratio of inertial to viscous forces.
For example, at high Reynolds number the flow is turbulent, characterized by unstable formations, such as eddies and vortices, while at low Reynolds number the flow is laminar (usually smooth flow).

Reynolds number as a measure is very useful for aerodynamic engineers which are trying to match data produced by wind tunnels testing with real track data. This is also one the very possible reasons for data correlation mismatch (a popular topic in F1 world) - the Reynolds number is different on a wind tunnel scaled-down model and real car, because the boundary layer is different.

The formula is simple: 

where:

• v = is the mean velocity of the object relative to the fluid (m/s)
• L = characteristic linear dimension, (travelled length of the fluid) (m)
• mu = is the dynamic viscosity of the fluid (Pa·s or N·s/m² or kg/(m·s))
• u =  is the kinematic viscosity (v = mu / p) (m²/s)
• p = density of the fluid (kg/m³)

Hence:

Laminar flow: Re < 2000
Transitional flow: 2000 < Re < 4000
Turbulent flow: Re > 4000

SLAT
[Explanation]
This is part of multi-element wing which is installed ahead of leading edge of the airfoil, below the main element. Certainly, it's there to create more efficiency and downforce. See picture below - a typical aircraft installment, imagine it reversed for a race car.

[Picture]

STRAKE
[Explanation]
A flat plate body fixed to race car in order to control and direct airflow (falls under the general category of Flow conditioners).

[Picture]

Original concept: deus1066, Model remix: F1 Framework

TURNING VANES
[Explanation]
The turning vanes on the picture below are rather Mclaren style, as opposed to the L-shaped from Red Bull and recent 2012 Ferrari incarnations. Turning vanes serve similar purpose to bargeboards, but are usually smaller in size. They started as very simple elements, like the ones highlighted with blue below, but have turned into increasingly complex in the recent years, given the strong aerodynamic profiles of modern Formula 1 cars.

[Picture]

Original concept: deus1066, Model remix: F1 Framework

VENTURI
[Explanation]
Here we will talk about both the effect and the tube, named after the Italian physicist Giovanni Battista Venturi.
The Venturi effect is a jet effect per se - in a tunnel the velocity of the fluid increases as the cross sectional area decreases, which is accompanied with a decrease of the static pressure.
In Formula 1 Venturi effect is closely related with underbody aerodynamics, which included shaped channels (before flat floors) aimed to accelerate the air and hence create low pressure areas.
See the picture below and imagine how and where can this be applied in a race car.
Again, the blue areas are low pressure ones and red are high.

[Picture]

Image credit:  http://www.symscape.com

VORTEX
[Explanation]
Vortex in aerodynamics is any fluid or gas formation which usually has turbulent flow. What is typical for a vortex is the low pressure at its core, which rises progressively as we go away from the center to the outer edges where the pressure is very high. This is one of the reasons why aero people generally would like to avoid creating vortices - the high pressure would mean lower velocity of the surrounding layers, thus drag.

Other reason why vortices are generally avoidable is because of the possibility of "vortex burst" - this is the moment where the formation literally breaks and creates even more turbulent and uncontrollable flow. This is less likely to happen with weak vortices and respectively, usually seen with strong vortices, where the core sometimes disintegrates into few smaller vortices.

The reason why, however, vortices are sometimes deliberately induced is to wake or re-energize the boundary layer - the small portion of air which is very close to a surface, where due to skin friction and resistance the velocity of the air is very low. We would like, as aero people, to have less drag, so we create a vortex generators - small winglets, which often induce normally rotating, weak vortices. The trade-off is the smaller portion of drag induced due to the shape of the device, but it's more beneficial in terms of L:D coefficient.
In F1 world we often hear the term referred to as "wingtip vortices", as seen on the picture below. The reason for creation of such formations is the natural tendency of the air to move from high to low pressure regions, being a continuous function. Here, since we operate with negative lift (downforce), the direction of the vortices is upwards.
These wingtip vortices, on the other hand, create lift-induced drag and drag is unwanted in any of its forms in motor sports, where speed matters.

[Picture]

VORTEX GENERATORS
[Explanation]
We have already explained what boundary layer is, so down on the alphabet we reached the vortex generators - small, usually vertical wings (or winglets, if you prefer - the synonym for small wing) whose purpose is re-energize the boundary layer, and thus increase the overall velocity of the air stream.
Generally, they are quite an easy way to direct air (flow conditioning) and enforce some turbulence close to the surface. In Formula1 cases we have even seen plastic-like Vortex Generators used on Toro Rosso's car - most probably a quick prototype parts, still, they do the job.

[Picture]

Original concept: deus1066, Model remix: F1 Framework

WAKE
[Explanation]
This is the turbulent disturbed air behind an object where the total pressure is low. Notice the 3D grid generated behind the wing's trailing edge below.

[Video]


YAW (PITCH AND ROLL)
[Explanation]
Yaw, in particular, is the motion of race car around a vertical axis, which occurs for example during steering.
All three directions are shown below.

[Picture]

Original concept: deus1066, Model remix: F1 Framework

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Congratulations, you have been very patient :)
Once again, this is just a reference point to some of the aero-related terms and devices in Formula 1. Some that are not included in the list, one reason or another: diffuser,  rake (article coming on that in the future, studying effect of diffuser angles and rake together), high velocity tunnels (ducts), F-duct like devices, NACA ducts (or "submerged inlets", due to their vortex-generating nature) but they will find their place at the F1 Framework in detailed articles.
As usual, I'm open to topic suggestions - next raft of blog posts are likely to be attributed to exotic technologies that can make it into F1.