Reynolds Number - Numberphile
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Date: 2022-04-09
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Comments and reviews: 9
arsenelupin123
You cannot literally time travel, pleaaaaase don't say things like that: P.
The internal forces dominate so at each time you can basically say that the fluid is not moving, solve for your velocity field, then change the time a bit and start again. It's quasistatic, and so it's reversible (there is an equation of state at each time.
But please, don't say it's time travel XD
But still, amazing experiment, and yes, great application of Reynolds' number.
reply
You cannot literally time travel, pleaaaaase don't say things like that: P.
The internal forces dominate so at each time you can basically say that the fluid is not moving, solve for your velocity field, then change the time a bit and start again. It's quasistatic, and so it's reversible (there is an equation of state at each time.
But please, don't say it's time travel XD
But still, amazing experiment, and yes, great application of Reynolds' number.
reply
tryAGAIN
I'd like to ask a question for Tom Crawford if I may? In the left side of the second NS eq, you have density (small rho) multiplied by a change in velocity (usually a delta v/delta t. I'm not sure if I'm just not understanding the semantics, but are you doing a derivative of velocity with respect to time (du/dt) or is it a Delta vel / Delta t? I'm just not used to seeing capital D used for either of these. Or is this a convention I've not some across yet?
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I'd like to ask a question for Tom Crawford if I may? In the left side of the second NS eq, you have density (small rho) multiplied by a change in velocity (usually a delta v/delta t. I'm not sure if I'm just not understanding the semantics, but are you doing a derivative of velocity with respect to time (du/dt) or is it a Delta vel / Delta t? I'm just not used to seeing capital D used for either of these. Or is this a convention I've not some across yet?
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Alex
Is there anything special if the Reynold's number is 1? Often with dimensionless numbers something happens not just when it's really big, but also when it's one. But my intuition says the only thing that will happen is that it's describing something between the really slow flow in a high viscosity situation and the super fast turbulent flow, and -something in between those two- doesn't sound too interesting.
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Is there anything special if the Reynold's number is 1? Often with dimensionless numbers something happens not just when it's really big, but also when it's one. But my intuition says the only thing that will happen is that it's describing something between the really slow flow in a high viscosity situation and the super fast turbulent flow, and -something in between those two- doesn't sound too interesting.
reply
Bryn. S.
Answer -The Particle Problem in the General Theory of Relativity- and you will
Know why. .Why a charge is its own CP inverse, avoiding singularities and infinities.
Use Two charge (CP & 1/Cp) in SU3(Q. G). Plan units density, pressure and viscosity of C P T.
Path of least action (Sterographic projection SU3 > S2. Field are fundemetal. mass without mass.
More like a CPT Superfluid theory.
reply
Answer -The Particle Problem in the General Theory of Relativity- and you will
Know why. .Why a charge is its own CP inverse, avoiding singularities and infinities.
Use Two charge (CP & 1/Cp) in SU3(Q. G). Plan units density, pressure and viscosity of C P T.
Path of least action (Sterographic projection SU3 > S2. Field are fundemetal. mass without mass.
More like a CPT Superfluid theory.
reply
Benoit
Saying the Navier-Stokes equations is valid for any -fluid flow- might not be entirely accurate. It begins to fail between the transition from viscous to rarefied flows and beyond of course. In fact, the presence of the second order derivative terms within the equations are approximations, these can be expressed in convective terms by developing the equations differently.
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Saying the Navier-Stokes equations is valid for any -fluid flow- might not be entirely accurate. It begins to fail between the transition from viscous to rarefied flows and beyond of course. In fact, the presence of the second order derivative terms within the equations are approximations, these can be expressed in convective terms by developing the equations differently.
reply
Andrew
No own or fresh idea. Just copy/paste from textbooks written by ignoramuses. For people who are interested in subject: Re number represent excess of incoming energy over dissipated or out-coming. It is closely related to transition to turbulence - in simple words change to flow behaviour to accommodate excess of IN energy over OUT energy.
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No own or fresh idea. Just copy/paste from textbooks written by ignoramuses. For people who are interested in subject: Re number represent excess of incoming energy over dissipated or out-coming. It is closely related to transition to turbulence - in simple words change to flow behaviour to accommodate excess of IN energy over OUT energy.
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Mr.
Do we not understand turbulence simply because modeling it is so complicated and takes so much computing power? Or is there something more fundamental that we don't understand about turbulence? Like, for instance, we know /that/ it occurs, but do we not know /why/ it occurs? Or is it simply, we don't know /how/ it occurs?
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Do we not understand turbulence simply because modeling it is so complicated and takes so much computing power? Or is there something more fundamental that we don't understand about turbulence? Like, for instance, we know /that/ it occurs, but do we not know /why/ it occurs? Or is it simply, we don't know /how/ it occurs?
reply
George
Pi is not fixed. Pi appears in so many equations that are unrelated to circles. For example, take the heegner numbers and their special properties, or Ramanujan's gorgeous series and approximations of pi. Even take him and Hardy's partition formula. Pi appears everywhere.
Especially in the cake shop.
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Pi is not fixed. Pi appears in so many equations that are unrelated to circles. For example, take the heegner numbers and their special properties, or Ramanujan's gorgeous series and approximations of pi. Even take him and Hardy's partition formula. Pi appears everywhere.
Especially in the cake shop.
reply
Kieran
Viscosity is still really important for high Reynolds number flows however. The fluid flowing around an object observes the inviscid shape of an object, and that's what neglecting the viscosity term will find. When viscosity is included, we the observe other behaviour such as boundary layer effects.
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Viscosity is still really important for high Reynolds number flows however. The fluid flowing around an object observes the inviscid shape of an object, and that's what neglecting the viscosity term will find. When viscosity is included, we the observe other behaviour such as boundary layer effects.
reply
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