Sven Littkowski <jam### [at] yahoocom> wrote:
> Parks are nice, but don't forget some playgrounds for children, some
> small forests, small lakes or creeks for fishing or observation or
> romance, and some emissionless transportation systems.   :-)
> Golf places, and such.

Golf would be really interesting in a rotating environment.  (Technically, the
Earth's rotation does affect golf on Earth, but the effect is too small to
notice.  The effect is noticeable to a long-range sniper, however.)

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On 2/3/2016 9:01 AM, Cousin Ricky wrote:
> Sven Littkowski <jam### [at] yahoocom> wrote:
>> Parks are nice, but don't forget some playgrounds for children, some
>> small forests, small lakes or creeks for fishing or observation or
>> romance, and some emissionless transportation systems.   :-)
>> Golf places, and such.
>
> Golf would be really interesting in a rotating environment.  (Technically, the
> Earth's rotation does affect golf on Earth, but the effect is too small to
> notice.  The effect is noticeable to a long-range sniper, however.)
>
>

One thing I am not sure about is if the air within the cylinder rotates 
at the same speed as the buildings and people.


Mike

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> On 2/3/2016 9:01 AM, Cousin Ricky wrote:
>> Sven Littkowski <jam### [at] yahoocom> wrote:
>>> Parks are nice, but don't forget some playgrounds for children, some
>>> small forests, small lakes or creeks for fishing or observation or
>>> romance, and some emissionless transportation systems.   :-)
>>> Golf places, and such.
>>
>> Golf would be really interesting in a rotating environment.
>> (Technically, the
>> Earth's rotation does affect golf on Earth, but the effect is too
>> small to
>> notice.  The effect is noticeable to a long-range sniper, however.)
>>
>>
>
> One thing I am not sure about is if the air within the cylinder rotates
> at the same speed as the buildings and people.
>
>
> Mike

Mostly, the air must rotate at the same speed as the whole abitacle. 
There is some slight convection, and there must be some devices causing 
artificial winds just so that air don't become stale.

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Am 03.02.2016 um 23:16 schrieb Alain:

>> One thing I am not sure about is if the air within the cylinder rotates
>> at the same speed as the buildings and people.
>>
>>
>> Mike
> 
> Mostly, the air must rotate at the same speed as the whole abitacle.
> There is some slight convection, and there must be some devices causing
> artificial winds just so that air don't become stale.

If you have the slightest amount of convection, air closer to the center
will probably rotate /faster/ than the cylinder, due to the coriolis effect.

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Mike Horvath <mik### [at] gmailcom> wrote:
> On 2/3/2016 9:01 AM, Cousin Ricky wrote:
> > Sven Littkowski <jam### [at] yahoocom> wrote:
> >> Parks are nice, but don't forget some playgrounds for children, some
> >> small forests, small lakes or creeks for fishing or observation or
> >> romance, and some emissionless transportation systems.   :-)
> >> Golf places, and such.
> >
> > Golf would be really interesting in a rotating environment.  (Technically, the
> > Earth's rotation does affect golf on Earth, but the effect is too small to
> > notice.  The effect is noticeable to a long-range sniper, however.)
> >
> >
>
> One thing I am not sure about is if the air within the cylinder rotates
> at the same speed as the buildings and people.
>
>
> Mike

nobody knows.  here is somebody who knows more than most;
https://youtu.be/_1yOe-exq6c?t=6m

i checked some time in the past and if remember correctly the speed of air
molecules is about the same as the velocity of the circumference of such a
rotating hab, so the air is weakly bound to the 'ground'.  my guess is that the
air doesn't want to follow along the rotation so it lags, making an antispin
breeze.  or a gale.  and creates drag, leading to instability (unless actively
corrected) for undersquare cylinders.  just a guess.

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On 2/3/2016 6:36 PM, clipka wrote:
> Am 03.02.2016 um 23:16 schrieb Alain:
>
>>> One thing I am not sure about is if the air within the cylinder rotates
>>> at the same speed as the buildings and people.
>>>
>>>
>>> Mike
>>
>> Mostly, the air must rotate at the same speed as the whole abitacle.
>> There is some slight convection, and there must be some devices causing
>> artificial winds just so that air don't become stale.
>
> If you have the slightest amount of convection, air closer to the center
> will probably rotate /faster/ than the cylinder, due to the coriolis effect.
>

Interesting.

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On 2/3/2016 7:50 PM, green wrote:
> nobody knows.  here is somebody who knows more than most;
> https://youtu.be/_1yOe-exq6c?t=6m
>
> i checked some time in the past and if remember correctly the speed of air
> molecules is about the same as the velocity of the circumference of such a
> rotating hab, so the air is weakly bound to the 'ground'.  my guess is that the
> air doesn't want to follow along the rotation so it lags, making an antispin
> breeze.  or a gale.  and creates drag, leading to instability (unless actively
> corrected) for undersquare cylinders.  just a guess.
>
>

The audio in that video is real bad. I can't understand the speaker.


Mike

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AIR MOVEMENT WITHIN A ROTATING CYLINDER

1
Even air has its mass, and thus also some small amount of inertia.
That's the first thing we need to keep in our mind.

2
The second thing we need to keep in mind, is that air is also flexible,
like all gases.

3
The third thing to consider is, that air gains different weights when
heated up or cooled down.

Prediction
The rotation of the cylinder, especially on its inner surface with all
the buildings and plants, will push the air with it, and thus create a
general air movement towards the same direction as the cylinder rotates.
But because air has its own mass, that movement tends to slow down
towards the inner axis of the cylinder due the own inertia of the air
and its flexibility. On the other hand, the steady and permanent
rotation of the outside air still adds new energy into the air flow,
that is why the rotation will never be zero at the center of the
cylinder. It will just be slower. The surfaces of all the buildings and
plants, even of moving humans and maybe animals, will cause
irregularities in that air movement, those can add to small and
relatively gentle winds under some circumstances, in a cylinder of that
small size (relatively seen). Also, inside that cylinder with light
sources, engines, humans and maybe animals, there will be a generation
of temperatures that are a bit higher than the regular air. Thus, that
warmer and now lighter air will rise towards the center of the cylinder
and thus at the same time causes the cooler and slightly heavier air to
make place and sink downwards, another factor for irregularities in air
movement and generation of gentle winds.

Altogether, I think, inside that cylinder once it has some volume of air
inside, there will be some gentle winds, but probably much below the
speed of 3 km/hour. Along the middle axis (center) of the cylinder, the
air will be much warmer, also towards the light source at the one side
of the cylinder, if I understand that concept correctly. Cooler air from
the sides will move towards the light source, get warmed up (probably),
and moves then along the middle axis. So we talk about two principal air
flows: (A) with the rotation of the cylinder, and (B) from all inner
walls towards the light source end of the cylinder and from there along
the center axis of the cylinder.

This seems to be a guaranty for pleasant, gentle winds. During night
hours, when the light source at the one end of the cylinder is probably
switched off, only the air movement (A) remains. During "day" hours, (A)
and (B) cause air movements.

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On 4-2-2016 2:13, Mike Horvath wrote:
> On 2/3/2016 6:36 PM, clipka wrote:
>> Am 03.02.2016 um 23:16 schrieb Alain:
>>
>>>> One thing I am not sure about is if the air within the cylinder rotates
>>>> at the same speed as the buildings and people.
>>>>
>>>>
>>>> Mike
>>>
>>> Mostly, the air must rotate at the same speed as the whole abitacle.
>>> There is some slight convection, and there must be some devices causing
>>> artificial winds just so that air don't become stale.
>>
>> If you have the slightest amount of convection, air closer to the center
>> will probably rotate /faster/ than the cylinder, due to the coriolis
>> effect.
>>
>
> Interesting.

Time to read "Rendezvous with Rama" by Arthur C. Clarke.

-- 
Thomas

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Time that they make a good movie from those books, too.   :-)

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