Subcritical flow studies on two-dimensional external compression supersonic inlets

1992 ◽  
Vol 8 (4) ◽  
pp. 849-856 ◽  
Author(s):  
K. Kapoor ◽  
T. G. Pai ◽  
B. N. Pamadi
Keyword(s):  
Two Dimensional ◽  
External Compression ◽  
Subcritical Flow

Two-dimensional leaps in near-critical flow over isolated orography

2005 ◽  
Vol 461 (2064) ◽  
pp. 3747-3763 ◽  
Author(s):  
E.R Johnson ◽  
G.G Vilenski
Keyword(s):  
Unsteady Flow ◽  
Equations Of Motion ◽  
Fold Increase ◽  
Flow Speed ◽  
Two Dimensional ◽  
Subcritical Flow ◽  
One Dimensional ◽  
Petviashvili Equation ◽  
Lee Wave ◽  
Supercritical Flows

This paper describes steady two-dimensional disturbances forced on the interface of a two-layer fluid by flow over an isolated obstacle. The oncoming flow speed is close to the linear longwave speed and the layer densities, layer depths and obstacle height are chosen so that the equations of motion reduce to the forced two-dimensional Korteweg–de Vries equation with cubic nonlinearity, i.e. the forced extended Kadomtsev–Petviashvili equation. The distinctive feature noted here is the appearance in the far lee-wave wake behind obstacles in subcritical flow of a ‘table-top’ wave extending almost one-dimensionally for many obstacles widths across the flow. Numerical integrations show that the most important parameter determining whether this wave appears is the departure from criticality, with the wave appearing in slightly subcritical flows but being destroyed by two-dimensional effects behind even quite long ridges in even moderately subcritical flow. The wave appears after the flow has passed through a transition from subcritical to supercritical over the obstacle and its leading and trailing edges resemble dissipationless leaps standing in supercritical flow. Two-dimensional steady supercritical flows are related to one-dimensional unsteady flows with time in the unsteady flow associated with a slow cross-stream variable in the two-dimensional flows. Thus the wide cross-stream extent of the table-top wave appears to derive from the combination of its occurrence in a supercritical region embedded in the subcritical flow and the propagation without change of form of table-top waves in one-dimensional unsteady flow. The table-top wave here is associated with a resonant steepening of the transition above the obstacle and a consequent twelve-fold increase in drag. Remarkably, the table-top wave is generated equally strongly and extends laterally equally as far behind an axisymmetric obstacle as behind a ridge and so leads to subcritical flows differing significantly from linear predictions.

scholarly journals Multiplanar and two-dimensional imaging of central airway stenting with multidetector computed tomography

2012 ◽  
Vol 7 ◽  
Author(s):  
Mehmet Akif Ozgul ◽  
Guler Ozgul ◽  
Erdogan Cetinkaya ◽  
Yasin Abul ◽  
Gamze Kirkil ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Multidetector Computed Tomography ◽  
Slice Thickness ◽  
Two Dimensional ◽  
External Compression ◽  
Non Invasive ◽  
Airway Stenting ◽  
Dimensional Reconstruction ◽  
Stent Diameter

Background: Multidetector computed tomography (MDCT) provides guidance for primary screening of the central airways. The aim of our study was assessing the contribution of multidetector computed tomography- two dimensional reconstruction in the management of patients with tracheobronchial stenosis prior to the procedure and during a short follow up period of 3 months after the endobronchial treatment. Methods: This is a retrospective study with data collected from an electronic database and from the medical records. Patients evaluated with MDCT and who had undergone a stenting procedure were included. A Philips RSGDT 07605 model MDCT was used, and slice thickness, 3 mm; overlap, 1.5 mm; matrix, 512x512; mass, 90 and kV, 120 were evaluated. The diameters of the airways 10 mm proximal and 10 mm distal to the obstruction were measured and the stent diameter (D) was determined from the average between D upper and D lower. Results: Fifty-six patients, 14 (25%) women and 42 (75%) men, mean age 55.3 ± 13.2 years (range: 16-79 years), were assessed by MDCT and then treated with placement of an endobronchial stent. A computed tomography review was made with 6 detector Philips RSGDT 07605 multidetector computed tomography device. Endobronchial therapy was provided for the patients with endoluminal lesions. Stents were placed into the area of stenosis in patients with external compression after dilatation and debulking procedures had been carried out. In one patient the migration of a stent was detected during the follow up period by using MDCT. Conclusions: MDCT helps to define stent size, length and type in patients who are suitable for endobronchial stinting. This is a non-invasive, reliable method that helps decisions about optimal stent size and position, thus reducing complications.

Two-Dimensional Simulation of Subcritical Flow at a Combining Junction: Luxury or Necessity?

2010 ◽  
Vol 136 (10) ◽  
pp. 799-805 ◽  
Author(s):  
Rabih Ghostine ◽  
Robert Mose ◽  
José Vazquez ◽  
Abdellah Ghenaim ◽  
Caroline Grégoire
Keyword(s):  
Two Dimensional ◽  
Subcritical Flow ◽  
Dimensional Simulation
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