Ross Tucker Does Not Understand Aerodynamics/Wind-Tunnel

He posted a bunch of pictures without giving any measurements. And he also didn't account for the fact that the clock was above the heads of the runners.

You could easily ask Chris and Andrew (pacers) how it felt being behind the car, since they were way closer than Kipchoge. I mean, for me their words, in the interview posted on the home page, are already a testimony how incredible Kipchoge's run was.

Agree, there is no way Tesla's clock was making much of a difference.

First were shoes, then clock, what's next?

HGL wrote:

He has no understanding of wind aerodynamics and how that car traveling at the speed it was traveling still allowed the wind to fall in front of the pacers. A simple test would prove this out rather than his poorly informed opinion.

Let's look at a picture and make some estimations.

The car is traveling at 13-14 mph (~6 m/sec)

Say that the clock on top of the car is 2m across.

Kinematic viscosity of air @ 20C is 15.1E-6 m2/sec

Reynold's Number = Length * Velocity / Kinematic Viscosity

Reynold's Number = 7.9E5 approximately.

For a Reynold's Number of 10^5-10^6 you are definitely going to have boundary layer separation around the giant clock.

If you assume that the clock is 1 meter across the Reynold's number is then

~4E5. Still well above the range where you will have boundary layer separation.

The air travelling around the clock is not going to neatly slipstream behind it.

HGL wrote:

He needs to stick to his pseudo science.

Sorry to be a pedant, but if he's wrong about the Tesla, isn't he already engaging in pseudoscience? Isn't your suggestion rather like telling A-Rod to knock off the 'roids and return to his accustomed ways?

I believe that Nike did wind tunnel tests and determined the exact turbulence caused by the Tesla/clock and determined where the pacers needed to run to give the best effect to kipchoge

Actually, the shape of the car/clock would create turbulence behind the clock.

This could only have hindered the effort.

The spacing was such that the turbulence was probably minimized.

whatever the tesla and all the pacers actually mean, perhaps not that much, perhaps enough to make it happen. it was of some importance.

therefore i like the analogy with the everest. imagine a climber and he does it with oxygen bottles, supporters and ropes fixed before by friendly sherpas.

Jimmy21 wrote:

I̶ ̶b̶e̶l̶i̶e̶v̶e̶ ̶t̶h̶a̶t̶ Nike did wind tunnel tests and determined the exact turbulence caused by the Tesla/clock and determined where the pacers needed to run to give the best effect to kipchoge

Fixed it for you.

Yes, they are probably placed outside of the turbulent wake but within the laminar wake. This is the optimal place for deceasing drag.

Engineer wrote:

Bro - Mama wrote:

Actually, the shape of the car/clock would create turbulence behind the clock.

This could only have hindered the effort.

The spacing was such that the turbulence was probably minimized.

Yes, they are probably placed outside of the turbulent wake but within the laminar wake. This is the optimal place for deceasing drag.

The turbulent air would cause less drag on the runners than the smooth laminar air. You know this, surely?

wow, we have some really slow people on here! I'm assuming most are from the US and not very bright when it comes to math and science. Thank you for bringing up the turbulent v. laminar wake (finally some reason!)and here is a tidbit on relative power:https://hetgeheimvanhardlopen.nl/wp-content/uploads/2017/05/23-The-power-of-Eliud-Kipchoge.pdf?utm_source=Master%20List&utm_campaign=20e7d445c9-EMAIL_CAMPAIGN_2017_04_03&utm_medium=email&utm_term=0_e3b59af547-20e7d445c9-193134145&mc_cid=20e7d445c9&mc_eid=4e008efe1fUse some common sense people! Do we really think Nike didn't think about that over-size clock design and it's distance from the V formation of the pacers?! I mean come on...

Engineer wrote:

Bro - Mama wrote:

Actually, the shape of the car/clock would create turbulence behind the clock.

This could only have hindered the effort.

The spacing was such that the turbulence was probably minimized.

Yes, they are probably placed outside of the turbulent wake but within the laminar wake. This is the optimal place for deceasing drag.

Fluids 101 wrote:

Engineer wrote:

Yes, they are probably placed outside of the turbulent wake but within the laminar wake. This is the optimal place for deceasing drag.

The turbulent air would cause less drag on the runners than the smooth laminar air. You know this, surely?

Turbulent separation causes less drag on an object than laminar separation for a laminar, uniform free stream velocity.

This analysis says nothing about whether or not it is preferable to have the free stream flow around the runners be turbulent or laminar.

My take that Nike positioned the runners outside of the turbulent wake and but within the laminar wake is of course speculation, having not done wind tunnel testing or CFD. I presume that Nike did do their due diligence though. ;)

Engineer wrote:

Fluids 101 wrote:

The turbulent air would cause less drag on the runners than the smooth laminar air. You know this, surely?

Turbulent separation causes less drag on an object than laminar separation for a laminar, uniform free stream velocity.

This analysis says nothing about whether or not it is preferable to have the free stream flow around the runners be turbulent or laminar.

My take that Nike positioned the runners outside of the turbulent wake and but within the laminar wake is of course speculation, having not done wind tunnel testing or CFD. I presume that Nike did do their due diligence though. ;)

Why do you say the laminar region is ideal for decreasing drag? The turbulent region decreases drag because there is simply less air. The same reason it is difficult to swim in white water.

HGL wrote:

He needs to stick to his pseudo science.

He has no understanding of wind aerodynamics and how that car traveling at the speed it was traveling still allowed the wind to fall in front of the pacers. A simple test would prove this out rather than his poorly informed opinion.

Furthermore, the car left Kipchoge shortly after 35km, after he was no longer able to keep pace.

The dude is a pseudo science quack. I remember a few years back I had a back and forth with him on a swimming topic - something I have expertise in. The guy proved himself to be an idiot. He had just made up facts and provided unfounded claims. When I confronted him with actual research on the topic, he said he was ending the conversation because it was going nowhere.

If you read a lot of his posts on his website, there is a significant amount of bro-science on there.

Engineer wrote:

Bro - Mama wrote:

Actually, the shape of the car/clock would create turbulence behind the clock.

This could only have hindered the effort.

The spacing was such that the turbulence was probably minimized.

Yes, they are probably placed outside of the turbulent wake but within the laminar wake. This is the optimal place for deceasing drag.

+1

If there was no slipstreaming advantage to be had Nike wouldn't have stuck a butt-ugly 2m x 1.5m square clock on the top of the Tesla.

Too bad that picture is not from the race.

Kipchoge was not in a black singlet for the attempt, he was in RED.

Also, the clock has an opening on the backside, thus reducing the drag of the Tesla, and thus, Kipchoge.

You guys are tools. He could run 2:00:25 in perfect conditions and perhaps much FASTER in race conditions RIGHT NOW.

I noticed it was just from a practice session but what's that thing falling out of Kipchoge's tights? Reminds me of that time when I went to school with a pair of panties clinging with static to the back of my shirt.

Come on people, the vast majority of the improvement from the current WR is the clock. If you don't believe Tucker, believe the guy below.

SCIENCEftw wrote:

wow, we have some really slow people on here! I'm assuming most are from the US and not very bright when it comes to math and science.

Thank you for bringing up the turbulent v. laminar wake (finally some reason!)

and here is a tidbit on relative power:

https://hetgeheimvanhardlopen.nl/wp-content/uploads/2017/05/23-The-power-of-Eliud-Kipchoge.pdf?utm_source=Master%20List&utm_campaign=20e7d445c9-EMAIL_CAMPAIGN_2017_04_03&utm_medium=email&utm_term=0_e3b59af547-20e7d445c9-193134145&mc_cid=20e7d445c9&mc_eid=4e008efe1f

The facts are Tucker said Kipchoge's run is worth a 2:01:40 in Berlin. The guy above says 2:02:18.

I pretty much agree with that. Let's use common sense people. You don't need a degree in science to figure this out.

The race on Saturday changed nothing for me. It confirmed what I already knew. We aren't close to sub-2 on a legitimate marathon and Kipchoge is 45-seconds to a minute better than anyone else in the world.

1) In 2016, Kipchoge repeatedly proved himself in 2016 to be 45-70 seconds better than the next marathoner on the planet.

Last year, he showed that on two occasions. He won London by 46 seconds and then he won the Olympics by 70 seconds. If you subtract 70 seconds form 2:02:57, you get 2:01:47. If you subtract 45 seconds, you get 2:02:12.

Before the race, it wouldn't have been a crazy stretch to think he could run 2:02-2:02:30 in Berlin if everything broke perfectly right and that's pretty much still what I'm thinking now that the sub-2 attempt is over.

Someone get back to me when he breaks 2:01:30 in Berlin. It ain't happening. I doubt he breaks 2:02.

HGL wrote:

He needs to stick to his pseudo science.

He has no understanding of wind aerodynamics and how that car traveling at the speed it was traveling still allowed the wind to fall in front of the pacers. A simple test would prove this out rather than his poorly informed opinion.

Furthermore, the car left Kipchoge shortly after 35km, after he was no longer able to keep pace.

Totally agree!

I was thinking the whole time people we grousing about wind break etc