Simple Tunnel ram Question

[digger]

I've been trying to discuss gravity's effect on vertical acceleration.

You are failing to look at all the vertical forces though

What are they? Name them. Define them. List the ones I have omitted.

You are not including the buoyancy force which is equal and opposite to gravity force thus cancels it out

[Kevin Johnson]

You are failing to look at all the vertical forces though

What are they? Name them. Define them. List the ones I have omitted.

You are not including the buoyancy force which is equal and opposite to gravity force thus cancels it out

It is a bit more complicated than this. https://en.wikipedia.org/wiki/Buoyancy

Tuner was pointing to a reduced or depressed local atmosphere which would display a lower pressure gradient. He is then considering a parcel or ensemble of particles/molecules that at a given point in time have a higher average density than that of the local atmosphere they are moving into. The acceleration due to gravity would then exceed the buoyancy force.

The counter is that the parcel is mixing with the local atmosphere and interacting with the molecules.

The counter is then that the mixing is not simultaneous across the boundaries of the parcel.

Another counter is that the parcel is not a valid construct...

And so it goes. Meanwhile, engineers like to have workable or pragmatic solutions to problems.

~~~~~~~~~~~~~~~~~~~~

Simplifications of the physics are so ingrained now in everyday life that they are ignored. Sometimes what is considered normal physics is deadly as when mine shafts contain stratified layers of deadly gases or inversions in lakes release large and also deadly quantities of carbon dioxide. http://www.slate.com/blogs/atlas_obscur ... f_co2.html

Yes, I know, more B.S. Saved you some trouble...

[GRTfast]

You are failing to look at all the vertical forces though

What are they? Name them. Define them. List the ones I have omitted.

You are not including the buoyancy force which is equal and opposite to gravity force thus cancels it out

It is a bit more complicated than this. https://en.wikipedia.org/wiki/Buoyancy

Tuner was pointing to a reduced or depressed local atmosphere which would display a lower pressure gradient. He is then considering a parcel or ensemble of particles/molecules that at a given point in time have a higher average density than that of the local atmosphere they are moving into. The acceleration due to gravity would then exceed the buoyancy force.

The counter is that the parcel is mixing with the local atmosphere and interacting with the molecules.

The counter is then that the mixing is not simultaneous across the boundaries of the parcel.

Another counter is that the parcel is not a valid construct...

And so it goes. Meanwhile, engineers like to have workable or pragmatic solutions to problems.

~~~~~~~~~~~~~~~~~~~~

Simplifications of the physics are so ingrained now in everyday life that they are ignored. Sometimes what is considered normal physics is deadly as when mine shafts contain stratified layers of deadly gases or inversions in lakes release large and also deadly quantities of carbon dioxide. http://www.slate.com/blogs/atlas_obscur ... f_co2.html

Yes, I know, more B.S. Saved you some trouble...

Great post. I’ve been thinking about how to say what you said in the first part of your post and have it be easily understandable by everyone. You did it though. Nice. The bottom line is, there is a lot going on. One of the legacy engineers at work that has been doing finite element analysis (structural, CFD, thermal, electrical) said something early in my career when helping me setup a complex model. I said “I want to make the model realistic”. He’s said “well it turns out that reality is pretty complicated”. That will always stick with me.

[SchmidtMotorWorks]

Diagram your theory and do an order of magnitude rough estimate of the consequences please.

[Kevin Johnson]

...One of the legacy engineers at work that has been doing finite element analysis (structural, CFD, thermal, electrical) said something early in my career when helping me setup a complex model. I said “I want to make the model realistic”. He’s said “well it turns out that reality is pretty complicated”. That will always stick with me.

"Analysis paralysis" I think is used.

[makin chips]

General relativity states that if gravity isn't a force, it can't accelerate objects. And any acceleration due to gravity isn't proper acceleration. It's considered coordinate acceleration.

So how does that come into play if proper acceleration isn't produced by gravity?

You guys lost me when it quit being 'simple'. I just thought I'd throw that in after reading it somewhere. Lol

[digger]

You are failing to look at all the vertical forces though

What are they? Name them. Define them. List the ones I have omitted.

You are not including the buoyancy force which is equal and opposite to gravity force thus cancels it out

It is a bit more complicated than this. https://en.wikipedia.org/wiki/Buoyancy

Tuner was pointing to a reduced or depressed local atmosphere which would display a lower pressure gradient. He is then considering a parcel or ensemble of particles/molecules that at a given point in time have a higher average density than that of the local atmosphere they are moving into. The acceleration due to gravity would then exceed the buoyancy force.

The counter is that the parcel is mixing with the local atmosphere and interacting with the molecules.

The counter is then that the mixing is not simultaneous across the boundaries of the parcel.

Another counter is that the parcel is not a valid construct...

And so it goes. Meanwhile, engineers like to have workable or pragmatic solutions to problems.

~~~~~~~~~~~~~~~~~~~~

Simplifications of the physics are so ingrained now in everyday life that they are ignored. Sometimes what is considered normal physics is deadly as when mine shafts contain stratified layers of deadly gases or inversions in lakes release large and also deadly quantities of carbon dioxide. http://www.slate.com/blogs/atlas_obscur ... f_co2.html

Yes, I know, more B.S. Saved you some trouble...

"drop" a dense pocket of air into "vacuum" hypothetically s, after 1 foot accelerating at 1g it is travelling at most 2.4m/s. this is compared to being accelerated to 150-180m/s due to pressure ratio. so its a small effect even in this unrealsitic case. In reality is there is a gradient within the runner so you are not going to have a small pocket of highly dense air in a low dense air field. so the effect is going to be even more neglibile in the overall scheme.

[GRTfast]

You are failing to look at all the vertical forces though

What are they? Name them. Define them. List the ones I have omitted.

You are not including the buoyancy force which is equal and opposite to gravity force thus cancels it out

It is a bit more complicated than this. https://en.wikipedia.org/wiki/Buoyancy

Tuner was pointing to a reduced or depressed local atmosphere which would display a lower pressure gradient. He is then considering a parcel or ensemble of particles/molecules that at a given point in time have a higher average density than that of the local atmosphere they are moving into. The acceleration due to gravity would then exceed the buoyancy force.

The counter is that the parcel is mixing with the local atmosphere and interacting with the molecules.

The counter is then that the mixing is not simultaneous across the boundaries of the parcel.

Another counter is that the parcel is not a valid construct...

And so it goes. Meanwhile, engineers like to have workable or pragmatic solutions to problems.

~~~~~~~~~~~~~~~~~~~~

Simplifications of the physics are so ingrained now in everyday life that they are ignored. Sometimes what is considered normal physics is deadly as when mine shafts contain stratified layers of deadly gases or inversions in lakes release large and also deadly quantities of carbon dioxide. http://www.slate.com/blogs/atlas_obscur ... f_co2.html

Yes, I know, more B.S. Saved you some trouble...

"drop" a dense pocket of air into "vacuum" hypothetically s, after 1 foot accelerating at 1g it is travelling at most 2.4m/s. this is compared to being accelerated to 150-180m/s due to pressure ratio. so its a small effect even in this unrealsitic case. In reality is there is a gradient within the runner so you are not going to have a small pocket of highly dense air in a low dense air field. so the effect is going to be even more neglibile in the overall scheme.

Agreed.

[j-c-c]

Wait, I did the math, 180m/s is nearly 400 mph, is that correct?

But that's in pure vacuum, with zero friction assumed, so we are in the real world not close to that, and gravity "contribution" mentioned is fairly close, correct again?

[digger]

Wait, I did the math, 180m/s is nearly 400 mph, is that correct?

But that's in pure vacuum, with zero friction assumed, so we are in the real world not close to that, and gravity "contribution" mentioned is fairly close, correct again?

180m/s = 0.52 mach

[Kevin Johnson]

We have gone through a goodly number of compressors and I have put the old tanks on one side of the shop to act as buffers/storage. The two compressors I am currently using are on the other side. They communicate with a long overhead pipe to a local manifold.

I shut down the compressors every day and close the main tank valves. Overnight, leaks in the various hoses/fittings bleed out the storage tanks to ambient. Every day when I open the main tank valves I get to hear the mad rush of air molecules racing across the shop from about 10 bar pressure (145psi) to 1 bar (14.5psi).

[Tuner]

You are failing to look at all the vertical forces though

What are they? Name them. Define them. List the ones I have omitted.

You are not including the buoyancy force which is equal and opposite to gravity force thus cancels it out

It is a bit more complicated than this. https://en.wikipedia.org/wiki/Buoyancy

Tuner was pointing to a reduced or depressed local atmosphere which would display a lower pressure gradient. He is then considering a parcel or ensemble of particles/molecules that at a given point in time have a higher average density than that of the local atmosphere they are moving into. The acceleration due to gravity would then exceed the buoyancy force.

The counter is that the parcel is mixing with the local atmosphere and interacting with the molecules.

The counter is then that the mixing is not simultaneous across the boundaries of the parcel.

Another counter is that the parcel is not a valid construct...

And so it goes. Meanwhile, engineers like to have workable or pragmatic solutions to problems.

~~~~~~~~~~~~~~~~~~~~

Simplifications of the physics are so ingrained now in everyday life that they are ignored. Sometimes what is considered normal physics is deadly as when mine shafts contain stratified layers of deadly gases or inversions in lakes release large and also deadly quantities of carbon dioxide. http://www.slate.com/blogs/atlas_obscur ... f_co2.html

Yes, I know, more B.S. Saved you some trouble...

"drop" a dense pocket of air into "vacuum" hypothetically s, after 1 foot accelerating at 1g it is travelling at most 2.4m/s. this is compared to being accelerated to 150-180m/s due to pressure ratio. so its a small effect even in this unrealsitic case. In reality is there is a gradient within the runner so you are not going to have a small pocket of highly dense air in a low dense air field. so the effect is going to be even more neglibile in the overall scheme.

Well now, finally a breath of fresh air, somebody gets it. Thank you. Someone else with the mathematical inclination to do so, calculate the the percentage of acceleration gravity supplies to the overall acceleration of the air mass. In racing where 1 % can be significant, 2 % is nothing to ignore. 150/2.4 = 62.5 1/62.5 = 0.016, so 1.6 %.

[MadBill]

Here's a real-world test that should brook no "ya buts": Big, high-power competition two stroke chainsaw engine with the typical diaphragm-type carb that can operate in any orientation. Fit the saw with a longish straight intake stack and optimize fueling on a precision dyno with the inlet pointing straight up. Now flip it upside down and re-optimize with the inlet pointing straight down. Report results.

[SchmidtMotorWorks]

Well now, finally a breath of fresh air, somebody gets it. Thank you. Someone else with the mathematical inclination to do so, calculate the the percentage of acceleration gravity supplies to the overall acceleration of the air mass. In racing where 1 % can be significant, 2 % is nothing to ignore. 150/2.4 = 62.5 1/62.5 = 0.016, so 1.6 %.

I ran a test far more sensitive than 1%, it showed nothing.

[GARY C]

The thing all of you are forgetting to factor in is the effect of a Magnetic Controlled Flat Earth!