Which of the black triangles produces less drag?

which of the black triangles produces less drag?

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grc.nasa.gov/www/k-12/airplane/dragco.html
gyazo.com/71c22a5f8b8a28be42e4d6809567bcae
en.wikipedia.org/wiki/Drag_coefficient
twitter.com/NSFWRedditGif

Upper one

Combine them and you have an aerodynamic figure

Lower one, just put a half sphere on the wide end of it.

tear drop is not formed base on aerodynamics.

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toppen eller lägre?

The lower one. The picture is intentionally deceiving. The arrows indicating airflow suggest that the airflow is coming from the right, while the text says it's coming from the left.

my b there, why do you think the lower one produces less drag?

What? What are you memeing, teardrop is one of the most aerodynamic shapes you fucking twat?!!!

the teardrop shape is a result of surface tension and gravity.

Why is cutting something better than beating it with a hammer?

i lack the strength to lift a hammer i'm sorry.

it's ok

Do you have autism, m8? Where did I claim that teardrop shape is naturally formed to be THE absolute perfect aerodynamic shape possible?

Would a teardrop shape produce less drag than the two options presented?

i might, ive never asked a doctor though so i can't be sure.

What's the answer OP?
My bet is on the lower one though

Which way is the air flowing? Left to right, or right to left?

read the foking image

i do not know, some people have said that it is the top one and even given an explanation before but i was still left uncertain.

dear oh dear, haven't you lazyfucks learned at high school that a cone placed in the opposite direction of airflow exhibits only a slightly better drag coefficient than a bloody flat plate, that is between 1.1 and 1

the upper orientation is far better than the lower with around 0.2 of drag coefficient. an airfoil (teardrop) would result in even less drag coefficient, down to 0.05

why is that though.

>the upper orientation is far better than the lower with around 0.2 of drag coefficient. an airfoil (teardrop) would result in even less drag coefficient, down to 0.05
You're talking out of your ass with pasting numbers onto it.
All this is highly dependent on the reynolds number which isn't given.

given the geometry of the surface that is exposed to the laminar airflow, its drag coefficient can easily be derived, google is your friend for that particular task:

grc.nasa.gov/www/k-12/airplane/dragco.html

The illustration and text were contradicting, asshat.

that is particularly why I said "between" 1-1.1 and "around" 0.2, and as low as 0.05. a flat surface shape can also be as high as 1.2, just as a cone can be even higher than 0.4 depending on the height.

>talking out of your ass
top counter argument

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if that you say is true shouldn't the perfectly aerodynamic shape be sharper in front than in back?

no, why should that be? a significant amount of drag is also produced by the turbulences at the leaving edge of the airflow, at the end of the geometry.

How do blue arrows present air moving from left to right when blue is the colour of the wind and they point left. Are a dumbling, OP?

My point was about the viscosity senpai.

n-n-no

anyone own a 2d or 3d aerodynamics simulator? run some cones through it both ways so we can finally have an answer.

your point about the not given reynolds number has no significance since it's imperative to assume the shapes are subject to the same laminar airflow that has high enough reynolds number, notice that nice plateau in your plot. why would anyone consider different airflows when comparing the drag coef of geometries

some folks have already did it and put the numbers in my old high school formula book from which I got them (0.2 for the upper, 1.1 for the lower when the height of cone is 5 times its base and at 1k of reynolds number)

???

>it's imperative to assume the shapes are subject to the same laminar airflow that has high enough reynolds number
according to whom?
> notice that nice plateau in your plot
Also notice that nice huge jump bewteen 10^5 and 10^6
>why would anyone consider different airflows when comparing the drag coef of geometries
Maybe because airflows can be a pretty huge deal to certain geometries

Just google the Cd numbers for the different configurations ffs

>according to whom?
that's common sense when folks like op are asking a simple comparison of drag between two shapes. otherwise a "comparison" makes no sense

>Also notice that nice huge jump bewteen 10^5 and 10^6
>what is turbulent flow

>Maybe because airflows can be a pretty huge deal to certain geometries
that's why you consider them at the SAME airflow, why are we discussing this anyway? it's like comparing resistivities of two metals, while calculating it at 1kelvin for the first and at room temp for the other.

technically, if we're talking about non-viscous flow, then they're both equal :^)

>Germany

In its natural element

You're most likely right with your answer to OP's question, i'm just pointing out that you have to be careful with throwing numbers at it, especially when separation is involved. That's why i took a sphere as an example.

hue

>throwing numbers
why do you keep ignoring the fact that they are APPROXIMATE numbers at common real world conditions of flow speed, temperature, air pressure etc. it's rather the student who's got to be careful when doing exact calculations, I am just trying to provide basic guidance here.

/thread 2bh

gyazo.com/71c22a5f8b8a28be42e4d6809567bcae

the drag coefficient is commonly denoted as cd

en.wikipedia.org/wiki/Drag_coefficient

>the 2 in the numerator

>the #FF0F21 of red shade in your flag
whay sort of a trolling is this now

Here you have a value for one of the cases (triangle flat face facing the flow)

Looks like you can continue here
Some have different answers depending on the Re number :^)

lmao fucking nerds in this thread

Satan pls

this, I don't /sci/ence on my funpost board.

at least in here it's still much better than watching self proclaimed pure math geniuses on /sci/ spilling out tremendous amounts of disinformation in physics

What's your degree user

phd in semiconductor physics

>WE WUZ CANNAE DRIVES AND SHIT

>phd
shit nigga. Where did you into fluid dynamics?

that's just some knowledge that I remember from back in high school years

thoughts on this?

>high school
Well i guess there they don't teach about separation points

lmao those people are clinically retarded

too many circumstances should come together for the airflow in that example to become turbulent. the claim in that post may only be valid for extremely low airflows where calculating the drag wouldn't make any sense at all. it's been years since I've stopped taking anything in that board seriously as a side note.

>low wieght of objects in question
>change of angle of attack
that would no longer be a shape drag comparison question then and you know it better that without all the details of the environment and pressure, such a question like op's cannot be answered

in better words, since op's question involves comparing the shapes in their GIVEN positions, all other parameters that could alter it have to be kept constant

does anyone have a 2d or 3d program? just run the same cone through 2 ways lets solve this for good.

2d or 3d aerodynamics program*

I'm on mobile phone so I can't help :/. Someone uses ANSYS fluent?

>too many circumstances should come together for the airflow in that example to become turbulent
Bruh you're aware that the amount of turbulence is highly dependent on the geometric dimensions right? (which aren't given)

>low wieght of objects in question
>change of angle of attack
What did he mean by this

Like i said the Reynolds number is a big deal. Germanbro is probably right in the most amount of cases, but low or high Reynolds phenomena can result in a surprising outcome.

May I ask you something about your school? What kind of school did you go?

I'm fairly good with it, but i graduated and lost acces to it

May I ask what's your degree?

Master in Electro-mechanical engineering

How is mechanical engineer 's request (or need?) in your country?
t. Mechanical engineering student

the fact that none of the details are given, it renders a simple drag coefficient comparison at same airflow, assuming same air pressure, temperature, object weights that is large enough to be unaffected by the force of drag (so that you can determine the actual bloody drag) to be the ultimate answer

>What did he mean by this
you don't change the angle of attack of neither of the shapes, you hold them steady in air and never let the airflow to deform/decompose/cause them to stall and measure the drag force. such flow separation would render the possibility of a shape comparison invalid

a so called gymnasium

Do you mean related to other engineering branches or engineers in general?
Because companies here are screaming for any type of them, but i guess that's also true for most non-meme STEM degrees nowadays

calm down, you're Mongol brothers, please don't fight

Sorry, but I trust superior German autism, do you even speak Belgian!?

>object weights
But what has weight to do with it?

>you don't change the angle of attack of neither of the shapes, you hold them steady in air and never let the airflow to deform/decompose/cause them to stall and measure the drag force. such flow separation would render the possibility of a shape comparison invalid
I was actually talking about that a laminar boundary layer is prone to separation, and that therefore the difference between a laminar and turbulent layer can make quite the difference, as seen in That's the same reason they add bumps to a golf ball, to reduce the amount of drag

2nd one

Maar de Belgische taal bestaat helemaal niet

>Like i said the Reynolds number is a big deal
couldn't you adimensionalize the problem though?

Related to other engineering branches.

It's already been adimensionalized otherwise you couldn't use Re number

>blue arrows represent air moving from left to right
>arrow pointing left

Shitty bait

>But what has weight to do with it?
I thought you or some other user was referring to the possibility of airflow changing the angle of attack of the object due to high drag force relative to the size/weight of it.

I cannot even keep track of it at this time of the day since I'm no longer that young. let's put this to end without trolling. op has provided no information about the properties of the air, nor the size of the objects. therefore we're left with absolutely nothing but comparing the Cd of those two shapes. I hope we're on the same page here. And accordingly the bottom orientation will result in a significantly higher Cd, considering the objects aren't dimensioned bizarrely.

The Reynolds number already is dimensionless

I'd say it's average. I don't believe there's a significant difference unless you're a chemical engineer. Those fuckers are probably all in for the money.
Really, "burgerlijk ingenieur" as it's called in Dutch is among the top three paying (and hardest) educations you can do here in Belgium. It's hard to fuck up no matter what you do.

fair enough

Thank you for your time

No problem senpai. How's it like in Italy? And how hard is it related to other studies?

With engineering you can have a steady job in Italy but if you want to earn good monies you have to look in foreign countries. You can earn good without expatriate but usually is hard.

In my opinion Engineering is hard but Physics and Mathematics are far more difficult

I don't know if they'll treat your foreign degree as equal here in Belgium.
Southern Europe as a pretty bad reputation at our universities, to the point they negatively adjust scores for students who went on erasmus.
I don't know the level of your engineering department, but you get the idea.

hard!=difficult. My course about electrical engines was probably a bit less difficult than Calculus III, but jesus that thing was a pain in the ass to study.

>engineers
>problems