Yes but you have used continuity to relate them. So your assuming they are related to as you have done, from the areas and velocities change by continuity . but they are fixed from the pump and the exit. The presence of the nozzle doesn't change either of these.
This is what I believe confuses...
I was wondering how a boundary layer would be dissipative of momentum if it was under the influence of a positive heat gradient.
I understand that the reason that we don't see the boundary pressure equal the stagnation pressure is that the boundary is dissipative (so excess pressure above...
Thanks @Dale Thornton
That really brings us back to something like the initial question. If for the fluid to be accelerated (at a convergence ) the resultant force must eventually be from outside the fluid where does it come from ?
I could think of a few alternatives
1. The walls of the pipe...
Thanks @Dale
If the system is defined as the whole inviscid fluid
I don't want to pre-empt your answer but this is what I don't get if it is the internal pressure gradient causing the acceleration.
Thanks @Dale
Yes I very much am confused by thinking of it as an isolated system
I was envisaging that if the force causes an acceleration in the system I would need to see an equal and opposite force on the system (say the whole system moving backwards) Your saying this does not need to occur...
Hi Dale,
No I'm happy for it to be 'hijacked', if you can answer how the Momentum change is resolved 'within' the liquid then I don't need to find the resultant force . My degrees of freedom proposition is only my attempt to understand what's happening to the momentum balance.
Cheers Quentin
Hi I have been dealing with a fluid mechanics pressure gradient problem and from a statistical view point I can see how it resolves itself but am puzzled as to how it can occur at the molecular scale from a conservation of linear momentum perspective if Momentum is a conserved quantity
While...
Thanks for all the replies
how is that so? if we go down to the molecular level and we say that the piston depresses just 1 molecular depth
then once the first layer moves 1 layer to the right it is in its final position (with a velocity of zero) KE~of zero it has now passed its...
Ok looks like we are both talking about the same gradient and resolution above the constriction .So this localized gradient would just get us back to the same 1ms flow above I don't see how it is really relevant to the mechanism that causes the flow to go from 1ms to 2ms at the expense of static...
Ok looks like we are both talking about the same gradient and resolution above the constriction .So this localized gradient would just get us back to the same 1ms flow above I don't see how it is really relevant to the mechanism that causes the flow to go from 1ms to 2ms at the expense of static...
Isn't that what I said ? that the kinetic energy of each layer is equal so shared over a smaller mass this means that each element is accelerating ? If you mean that the Kinetic Energy is increasing then yes that's what I am trying to understand . What physical mechanism causes this to occur at...
Hi I thought id repost a simplified scenario to try and get a broader audience to a question I really am stuck with
https://www.physicsforums.com/threads/instantaneous-bernoullis.867860/#post-5450743
I am trying to understand the physical mechanism that causes Bernoulli's pressure/velocity...
Thanks for the reply
If I apply the information above then we are further away from the pressure/velocity variation we know develops, not closer
Yes I agree that, in an actual experiment, we would see disturbances (I have seen exactly what you describe in creeks) but as 256bits alluded to...
Hi thanks for the reply . Yes it puzzles me a lot as I think Continuity only reconciles the pressure variation it doesn't explain how it develops.
Yes I am keeping it to an inviscid flow, I am not considering viscosity.