F1technical.net

thanks kilcoo.. im currently doing litereature review.. plan to try all the modelling and simulation during the break.. and next semester will start the real project..

i want to know.. if i model the car completely.. let say same body shape for both year (with diffuser).. but with different front and rear wing..

is it possible to do the meshing using simple computer with graphic card?
or it need to be scaled down in order to let the meshing better?

asdf10101 wrote:Cv = drag force?

i have read somewhere that for racing car.. the lower the better (< 0.4) but formula 1 it is between 0.7 to 1


edit

For example, typical examples of drag coefficients for typical automobiles are between 0.3 and 0.5. In particular,
1. 0.36 : Honda Civic (2001)
2. 0.31 : Honda Civic (2006)
3. 0.29 : Honda Accord Hybrid (2005)
4. 0.35 : Toyota MR2 (1998)
5. 0.34 : Ferrari F40 (1987)
6. 0.57 : Hummer H2 (2003)
7. 0.7-1.1 : Formula 1 car
Typical drag coefficients for some other bodies are:
1. 2.1 : smooth brick
2. 0.9 : bicycle + rider
3. 0.4 : rough sphere (Re =106)
4. 1.0-1.3 : person (upright)
5. 1.0 -1.1 : skier

source
ftp://ftp.colorado.edu/cuboulder/course ... agCoef.pdf

I think you'll find that the Cd of 2008/2009 cars is a bit higher than 0.7 to 1.1!

I think you'll find you are completey wrong, which makes me wonder why you are arguing the Cd numbers posted form a source.

The drag coefficient (Cd or Cx) is a number that describes a characteristic amount of aerodynamic drag caused by fluid flow, used in the drag equation. Two objects of the same frontal area moving at the same speed through a fluid will experience a drag force proportional to their Cd numbers. Coefficients for rough unstreamlined objects can be 1 or more, for smooth object much less.

Mercedes is working towards a Cd of .2.

The Lambo Countach, one of the least aero efficient sports car designs of all time, has a Cd of 0.42.

sorry about that, i must have been unclear. i was referring to 08/09 F1 cars, not road cars! In the current spec teams are trying to gain as much downforce as possible, and so the Cd has now risen over the 0.7 to 1.1 range that the source states.

Giblet wrote:I think you'll find you are completey wrong, which makes me wonder why you are arguing the Cd numbers posted form a source.

The drag coefficient (Cd or Cx) is a number that describes a characteristic amount of aerodynamic drag caused by fluid flow, used in the drag equation. Two objects of the same frontal area moving at the same speed through a fluid will experience a drag force proportional to their Cd numbers. Coefficients for rough unstreamlined objects can be 1 or more, for smooth object much less.

Mercedes is working towards a Cd of .2.

The Lambo Countach, one of the least aero efficient sports car designs of all time, has a Cd of 0.42.

My mistake

Us technically minded folk like to correct mistakes in a fast and concise way, or perceived ones.

anyone have
Lewis, R., Scott J.
Study of Two Car Interaction on the Mk2 F1 Car
Advantage CFD Project Report BA136, Brackley, UK 2004

i find it quite similar from what i plan to do.. (from Motor Sport Drives CFD Technology to a New Level, Presented at the Global Motorsports Conference, Frankfurt, Germany, Nov. 2004)
mind sharing? ive looked for it but i cant find it..

For CFD experts.. what would be the best physics to simulate f1 drafting on track where there is no wall (symmetry plane)
bold is what i think it is confirmed..

Space: 3D

Motion: Stationary

Material: Gas (Air)

Flow: Coupled flow @ Segregated flow

Equation of State: Constant Density @ Ideal Gas @ Polynomial Density

Energy: (If segregated flow was chosen)..
- Segregated Fluid Enthalpy @ Segregated Fluid Isothermal Model @ Segregated Fluid Temperature

Time: Implicit Unsteady @ Steady

Viscous Regime: Inviscid, Laminar, Turbulent

Turbulence: Detached Eddy Simulation @ Large Eddy Simulation @ Reynolds Averaged Navier Stokes

Subgrid Scale Turbulence: (for LES) Smagorinsky Subgrid Scale

LES Wall Treatment: All y+ wall teatment, low y+ wall treatment

Optional Physic Models:
- Lagrangian Multiphase
- Passive Scalar

haha, have you just posted all the options to every setting in your cfd package?

this is what cfd is, you must try and work out what best fits the particular case. otherwise all your project is getting a cfd package to solve a case.

and i fear you might get in to some trouble if you chose an LES based method.

kinda haha

btw im using cd adapco - star ccm+..
ive tried various settings for ahmed body 25 deg (exact dimension in 15x1.87x1.4 m3).. but i cant get the value of cd and cl.. any idea? for cd ive got 0.34 but cl its 0.8 something..

for information.. ive simulated wing (only) for various winglet (circle, semicircle, ellipse and no winglet) and ive got quite same result as the experiment in wind tunnel.. but not for ahmed body..

another question is..

If an object 1:1 is simulated and find its cd and cl.. then if same object but scaled to 1:5 and only in half (symmetry).. does it give the same result? cause ive tried same object and its quite close but not same.. so i wonder if its same or there is an equation to calculate it.. its impossible to multiply by 2 and then 5 cause thats way too large..

Anyone can confirm this?

For single f1 2009 car

Physics:

3D
Stationary
Gas > Air
Segregated Flow
Segregated Fluid Temperature
Ideal Gas
Implicit Unsteady
Turbulent
Reynolds Averaged Navier Stokes
K-epsilon Turbulence
Realizable K-eplison two layer
Two layer All y+ Wall Treatment

Setting

V = 200m/s
density = 1.1458
temperature = 35 degree celcius
pressure = 101325 Pa
viscosity ratio = 10

this is the result of scaled down model 1:5.. speed = 89.44272 m/s

Drag Coefficient Cd = 0.792941
Lift Coefficient Cl = 1.110576

Downforce = 0.5xAxClxρxV^2
= 0.5x0.109261x1.11037x1.1458x89.4425^2
= 556 kgm/s2 (half car)
= 1112 kgm/s2 (full car) ?

is this acceptable?