Talk:Venturi tube: Difference between revisions
imported>Paul Wormer (→Beta: new section) |
imported>Milton Beychok m (Response to Paul Wormer's comments) |
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I have a (small) problem with the height ''h'' in the Bernoulli equation. Now height is defined of a '''point''', which implies that there may a difference in gravitational attraction over the cross section (as opposed to the length) of a tube. Later ''h''<sub>1</sub> is canceled against ''h''<sub>2</sub> for the gravitational terms in a horizontal tube, which implies that ''h'' is assumed constant over the cross-sectional dimension. It seems to me that ''h'' is (approximated as) a function of ''one'' dimension. In cylinder coordinates with the axis of the tube as ''z''-axis, my guess is that ''h'' is a function of ''z'' only and not of ''r'' and θ. This is physically reasonable and allows cancellation of the gravitational terms in a horizontal tube. --[[User:Paul Wormer|Paul Wormer]] 07:49, 29 March 2010 (UTC) | I have a (small) problem with the height ''h'' in the Bernoulli equation. Now height is defined of a '''point''', which implies that there may a difference in gravitational attraction over the cross section (as opposed to the length) of a tube. Later ''h''<sub>1</sub> is canceled against ''h''<sub>2</sub> for the gravitational terms in a horizontal tube, which implies that ''h'' is assumed constant over the cross-sectional dimension. It seems to me that ''h'' is (approximated as) a function of ''one'' dimension. In cylinder coordinates with the axis of the tube as ''z''-axis, my guess is that ''h'' is a function of ''z'' only and not of ''r'' and θ. This is physically reasonable and allows cancellation of the gravitational terms in a horizontal tube. --[[User:Paul Wormer|Paul Wormer]] 07:49, 29 March 2010 (UTC) | ||
::Paul, if you believe that the Bernoulli equation should use ''z'' rather than ''h'', feel free to change it. [[User:Milton Beychok|Milton Beychok]] 15:04, 29 March 2010 (UTC) | |||
== Beta == | == Beta == | ||
I added another definition for β, but on second thought it seems that the first definition ('''d/D''') is superfluous. By referring to ''diameters'' it is assumed that tubes are cylindrical and then '''d''' and '''D''' do not need to be introduced in addition to the respective cross sections '''A<sub>1</sub>''' and '''A<sub>2</sub>'''. For non-cylindrical ducts one needs more dimensions, e.g., width and height for rectangular shaped ones.--[[User:Paul Wormer|Paul Wormer]] 08:01, 29 March 2010 (UTC) | I added another definition for β, but on second thought it seems that the first definition ('''d/D''') is superfluous. By referring to ''diameters'' it is assumed that tubes are cylindrical and then '''d''' and '''D''' do not need to be introduced in addition to the respective cross sections '''A<sub>1</sub>''' and '''A<sub>2</sub>'''. For non-cylindrical ducts one needs more dimensions, e.g., width and height for rectangular shaped ones.--[[User:Paul Wormer|Paul Wormer]] 08:01, 29 March 2010 (UTC) | ||
::I will revise the the definition of beta to use the areas as you suggest, and thanks for your comments. [[User:Milton Beychok|Milton Beychok]] 15:04, 29 March 2010 (UTC) | |||
Revision as of 10:04, 29 March 2010
This is a new article
This articles was written from scratch. Milton Beychok 15:30, 20 March 2010 (UTC)
Bernoulli equation
I have a (small) problem with the height h in the Bernoulli equation. Now height is defined of a point, which implies that there may a difference in gravitational attraction over the cross section (as opposed to the length) of a tube. Later h1 is canceled against h2 for the gravitational terms in a horizontal tube, which implies that h is assumed constant over the cross-sectional dimension. It seems to me that h is (approximated as) a function of one dimension. In cylinder coordinates with the axis of the tube as z-axis, my guess is that h is a function of z only and not of r and θ. This is physically reasonable and allows cancellation of the gravitational terms in a horizontal tube. --Paul Wormer 07:49, 29 March 2010 (UTC)
- Paul, if you believe that the Bernoulli equation should use z rather than h, feel free to change it. Milton Beychok 15:04, 29 March 2010 (UTC)
Beta
I added another definition for β, but on second thought it seems that the first definition (d/D) is superfluous. By referring to diameters it is assumed that tubes are cylindrical and then d and D do not need to be introduced in addition to the respective cross sections A1 and A2. For non-cylindrical ducts one needs more dimensions, e.g., width and height for rectangular shaped ones.--Paul Wormer 08:01, 29 March 2010 (UTC)
- I will revise the the definition of beta to use the areas as you suggest, and thanks for your comments. Milton Beychok 15:04, 29 March 2010 (UTC)