PIV Experiments to Measure the Velocity Field Just Downstream of an Oscillating Collapsible Tube

2007 ◽  
Author(s):  
Christopher D. Bertram ◽  
Nicholas K. Truong ◽  
Stephen D. Hall
Keyword(s):  
Cardiac Output ◽  
Cross Section ◽  
Venous Return ◽  
Circular Cross Section ◽  
External Pressure ◽  
Forced Expiration ◽  
Collapsible Tube ◽  
Pulmonary Capillaries ◽  
Pulmonary Airways ◽  
Almost All

Almost all vascular conduits in the human body, being flexible, collapse elastically to a non-circular cross-section when the external pressure sufficiently exceeds the internal. Examples include the brachial artery (sphygmomanometry), veins (everyday manoeuvres), pulmonary airways (forced expiration), pulmonary capillaries (zones 1 and 2), and the urethra (micturition). Venous collapse is involved in regulation of venous return, which in turn regulates cardiac output.

Collapse Tests on Externally Pressurized Toroids

2003 ◽  
Vol 125 (1) ◽  
pp. 91-96 ◽  
Author(s):  
J. Błachut
Keyword(s):  
Mild Steel ◽  
Cross Section ◽  
Carrying Capacity ◽  
Circular Cross Section ◽  
External Pressure ◽  
Outer Diameter ◽  
Load Carrying Capacity ◽  
The Third ◽  
Load Carrying ◽  
Toroidal Shells

The paper discusses the load-carrying capacity of toroidal shells with closed circular cross section and loaded by static external pressure. Details about the manufacturing, pre-experiment measurements and testing of three, nominally different, steel toroids are provided. Two of them were manufactured from mild steel by spinning two halves and then welding them around the inner and outer equatorial perimeters. The third one has been assembled by welding four 90-deg stainless elbows. The outer diameter of these models was about 300 mm and the wall thickness varied from 2.0 to 3.0 mm. The hoop radius-to-thickness ratio, r/t, varied from about 15 to 30. The experimental collapse pressures were in the range from 4 to 8 MPa. Comparisons with numerical results are also provided.

Collapse Tests on Externally Pressurised Toroids

2002 ◽  
Author(s):  
J. Blachut
Keyword(s):  
Mild Steel ◽  
Cross Section ◽  
Carrying Capacity ◽  
Circular Cross Section ◽  
External Pressure ◽  
Outer Diameter ◽  
Load Carrying Capacity ◽  
The Third ◽  
Load Carrying ◽  
Toroidal Shells

The paper discusses the load carrying capacity of toroidal shells with closed circular cross-section and loaded by static external pressure. Details about the manufacturing, pre-experiment measurements and testing of three, nominally different, steel toroids are provided. Two of them were manufactured from mild steel by spinning two halves and then welding them around the inner and outer equatorial perimeters. The third one has been assembled by welding four 90 deg, stainless elbows. The outer diameter of these models was about 300 mm and the wall thickness varied from 2.0 mm to 3.0 mm. The hoop radius-to-thickness ratio, r/t, varied from about 15 to 30. The experimental collapse pressures were in the range from 4 MPa to 8 MPa. Comparisons with numerical results are also provided.

Impact Theory Calculations of the Lift and Drag of Ducted Bodies

1962 ◽  
Vol 13 (4) ◽  
pp. 327-348 ◽  
Author(s):  
J. Tinkler
Keyword(s):  
Skin Friction ◽  
Cross Section ◽  
Circular Cross Section ◽  
External Pressure ◽  
Impact Theory ◽  
Overall Performance ◽  
Mach Numbers ◽  
Lift And Drag ◽  
Drag Ratio

SummaryNewtonian impact theory has been used to estimate the external pressure forces on ducted bodies of rectangular, circular and semi-circular cross section. With an allowance for skin friction (or other incidence-independent drag) it is shown that maximum lift/drag ratios of about three to four are possible with little effect of body geometry provided that short and very divergent, or tall and narrow rectangular ducts are avoided.Large changes occur in the separate lift and drag at maximum lift/drag ratio and these have to be made compatible with the weight and thrust capacity of the configurations. The maximum lift/drag ratio of a duct can be improved by the addition of wings, especially for a duct with poor lift/drag ratio, but the best overall performance is with a duct of good lift/drag ratio and low drag.It is anticipated that impact theory underestimates the pressure forces, and hence the lift/drag ratios, which would obtain at finite Mach numbers but the trends with geometrical changes should be reasonably reliable.

SAF file: It's really three dimensional file

2018 ◽  
Vol 14 (1) ◽  
pp. 1
Author(s):  
Prof. Dr. Jamal Aziz Mehdi
Keyword(s):  
Cross Section ◽  
Root Canal ◽  
Three Dimensional ◽  
Circular Cross Section ◽  
Circular Motion ◽  
Root Canal Treatment ◽  
Metal Core ◽  
Rotating Blade

The biological objectives of root canal treatment have not changed over the recentdecades, but the methods to attain these goals have been greatly modified. Theintroduction of NiTi rotary files represents a major leap in the development ofendodontic instruments, with a wide variety of sophisticated instruments presentlyavailable (1, 2).Whatever their modification or improvement, all of these instruments have onething in common: they consist of a metal core with some type of rotating blade thatmachines the canal with a circular motion using flutes to carry the dentin chips anddebris coronally. Consequently, all rotary NiTi files will machine the root canal to acylindrical bore with a circular cross-section if the clinician applies them in a strictboring manner

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