rwjefferson Posted May 9, 2013 Posted May 9, 2013 Does a vortex demonstrate centripetal or centrifugal force? honest queries deserve kind and honest replies Does a vortex demonstrate centripetal or centrifugal force and why does a twister so twist and spin and tango? memory is the second thing to go Does a vortex exhibit centripetal or centrifugal force? just ask.ing ron sometimes the best answer is yes and yes and no more threats or warnings
studiot Posted May 10, 2013 Posted May 10, 2013 Indeed the best answer is yes and yes. a parcel of fluid pursuing vortex, or other curved or rotary motion is no different from any other particle in mechanics. You have two choices for the analysis viz to calculate the actual forces acting in which case you would use centripetal force and Newton's laws of dynamics ( and viscoscity in a fluid). Alternatively you could go for D'Alembert's quasi static solution in which case you would apply the fictious intertial centrifugal force and consider the resultant equilibrium of the fluid parcel. For instance within a centrifugal pump, this force balance is provided by the reaction force of the casing on the pressure developed within the fluid by virtue of its motion.
rwjefferson Posted May 10, 2013 Author Posted May 10, 2013 good What does D'Alembert call the force that energizes a vortex? What do you? ron
studiot Posted May 12, 2013 Posted May 12, 2013 good What does D'Alembert call the force that energizes a vortex? What do you? Not sure what you mean by this question. If you mean what causes streamlines to curve perhaps you should study the Magnus effect. If you mean where does the energy come from to drive a vortex then it must come from the interaction of a fluid with its surroundings and Hamiltons principle. It is, however, important to distinguish between force and energy.
rwjefferson Posted May 13, 2013 Author Posted May 13, 2013 as you wish I am so sorry; now please cite the first word in phrase that escapes your limited vocabulary. What is the difference between the force and energy and power needed to accelerate and spin fluent matter into a whirlwind and where might flatlanders and you see a tornado twisting and spinning up and away? ron sometime between dreamtime and imagination -3
studiot Posted May 13, 2013 Posted May 13, 2013 I have already answered your question. Is English your first language? I will try to repeat in simpler terms. It is impossible for a vortex to develop in motionless air. There is energy of motion in moving air. During this motion the moving particles of air contact obstacles in their environment. These obstacles provide sideways forces on the moving air and sometimes also forces parallel to the flow. These interactions develop the necessary impetus to kick off the curving motion that leads to a vortex.
swansont Posted May 13, 2013 Posted May 13, 2013 as you wish I am so sorry; now please cite the first word in phrase that escapes your limited vocabulary. ! Moderator Note It should go without saying that this had better not be another trolling/setup thread, but I'll say it anyway. Further, insulting people is not acceptable. DO NOT further derail the thread by responding to this modnote. You may use the report post function if you feel it was in error.
robomont Posted May 25, 2013 Posted May 25, 2013 (edited) i always thought it was because of differences in polarity of molecules and there groupings into wide clusters in combination with the polarity of the ground surface.like a sandwich of negative positive negative.when the clouds charge to mass ratio gets high enough it creates a bubble streamer that gets the whole thing going.then the flushing toilet rule steps in .dont know real name.and takes over.two vortices in one .the inside ones charge takes dominance for magnetic field so the outer vortice is perpendicular to the inner.just a theory. Edited May 25, 2013 by robomont
MigL Posted May 25, 2013 Posted May 25, 2013 Gases and liquids move in response to differential pressure. Pressure 'pushes' from high pressure to lower pressure, and the resultant spiral direction of tornadoes or toilet bowls, is dependant on northern or southern hemisphere location. As studiot has already pointed out, using actual forces and Newtons laws of motion, the acceleration and force are inwards,into the centre of the vortex, and so centripetal in nature.
rwjefferson Posted May 25, 2013 Author Posted May 25, 2013 So what do you call the force that spins a vortex? ron
studiot Posted May 25, 2013 Posted May 25, 2013 So what do you call the force that spins a vortex? Usually it is a shear force (parallel to the motion) The shear force imparts curvature to the sraight motion of the air. When that curvature is suffiiciently great the curve turns right back on itself and a vortex is created. The shear is created in the first place by moving air brushing past something. This may be a mountain, it may be another mass of colder or warmer air or moister or dryer air or a tree or whatever.
rwjefferson Posted May 26, 2013 Author Posted May 26, 2013 inertial pressure differential.007 I did not ask for the direction of the force. Gases and liquids move in response to differential pressure. Pressure 'pushes' from high pressure to lower pressure, and the resultant spiral direction of tornadoes or toilet bowls, is dependant on northern or southern hemisphere location. may be MigL might be on to something What do you call the force that created heat and wind in the fist place? ron def: bang don't tell empress I still see through cloak
MigL Posted May 27, 2013 Posted May 27, 2013 The force IS the differential pressure. It is caused by differences in temperature, currents or winds in the liquid or gas, movement and rotation of the vessel, etc. Stop trying to goad and drive the discussion towards your own ends and speculative ideas. 3
rwjefferson Posted June 2, 2013 Author Posted June 2, 2013 yes.iii The force IS the differential pressure and what does it take to goad you into admitting vortex is the balance between inertia and differential pressure? Or there IS NO proof the force IS NOT delta pressure. Carry on. as you wish ron
ACG52 Posted June 2, 2013 Posted June 2, 2013 Or there IS NO proof the force IS NOT delta pressure. You can't prove a negative.
swansont Posted June 3, 2013 Posted June 3, 2013 yes.iii The force IS the differential pressure and what does it take to goad you into admitting vortex is the balance between inertia and differential pressure? Or there IS NO proof the force IS NOT delta pressure. Carry on. as you wish ron ! Moderator Note You've been repeatedly warned against the tactic of goading people into saying what you want them to say. In this very thread, even. If you're fishing for a particular answer, it's not an honest inquiry.
MigL Posted June 4, 2013 Posted June 4, 2013 What does this even mean ... "what does it take to goad you into admitting vortex is the balance between inertia and differential pressure?" If there are two forces that are balanced, there is no acceleration, and even elementary physics teaches that circular motion is accelerated motion. Did you fall asleep during those classes ?
rwjefferson Posted June 7, 2013 Author Posted June 7, 2013 insults flourish as reason fails Did you fall asleep during the "How to have a kind and well reasoned conversation" class? Again? honestly It might be just a quantum bit more dishonest to deny inertial pressure differential is a better model of force than curvature; even if the empress' new cloak lulled you to sleep during the science revolution. wakey wakey up up up /honestly def: ambivalence equal in verse opposite valence syn: N0 delta vortex works for me What do you call it when the force of attraction is equal to the force that resists change? ron~ oops I dood it again
studiot Posted June 9, 2013 Posted June 9, 2013 The force IS the differential pressure and what does it take to goad you into admitting vortex is the balance between inertia and differential pressure? Or there IS NO proof the force IS NOT delta pressure. I can see where you are coming from now, although as swansont said the wording could have been ameliorated. What definition of balance are you using? What definition of differential are you using?
Bignose Posted June 9, 2013 Posted June 9, 2013 [math]\rho \left( \frac{\partial \mathbf{v}}{\partial t} + \mathbf{v} \cdot \nabla \mathbf{v} \right) = - \nabla p + \nabla \mathbf{T} + \mathbf{b}[/math] rho is the fluid denisity v is the fluid velocity t is time p is the pressure T is the stress tensor and b is the body force This equation is known as the Navier Stokes equation for fluids. It is amazingly accurate at making predictions on how fluid moves. Note that there are many reasons fluids are in motion. The left hand side has acceleration & inertia in it. The right hand side has pressure differential, stress, and body forces in it. The above (typically-)second order differential equation also requires some kind of boundary conditions to solve it. And the boundary can be the sources or sinks of the various terms in the equation, such as accelerations or stresses or pressure differential. There are many texts written on fluid mechanics, which I will no reproduce here, but the wikipedia page is a decent free start. http://en.wikipedia.org/wiki/Navier%E2%80%93Stokes_equations If you want to learn more about it, just ask, and I can recommend texts based on what you tell me your background is.
rwjefferson Posted June 10, 2013 Author Posted June 10, 2013 its all so greek to me def: balance equality between opposing or interacting forces def: caveat these definitions are not necessarily found in flatland dictionaries def: differential difference in all forms et. al. that follows syn: ridiculous nonsense according to those that slept through the evolution of science If you still feel the need to convince me that a galaxy is not dam good model of a vortex stoke your navier posts to the speculations forum and prove it to me and beyond a reasonable doubt the force is not inertial pressure differential. ron -1
ACG52 Posted June 10, 2013 Posted June 10, 2013 syn: ridiculous nonsense according to those that slept through the evolution of science The ridiculous nonsense is what you're posting.
studiot Posted June 10, 2013 Posted June 10, 2013 def: balance equality between opposing or interacting forces Thank you, there is no need for the rest of the fancy language. So what exactly do do mean by equality? This is not a trick question since opposing equal forces can lead to a turning moment or couple, which is what you are seeking. This is not, however, true in an inertial analysis where we consider equilibrium as a result of the opposing action of centripetal and centrifugal forces.
hypervalent_iodine Posted June 14, 2013 Posted June 14, 2013 ! Moderator Note Sorry to all that this has taken so long to get around to. rwjefferson, You have been warned once about trolling in this thread. Enough is enough. If you aren't willing to make decent contributions to the site, don't expect to be here much longer. I am closing this thread as it does not seem to have any point except to act as an annoyance.
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