Unsteady Three-Dimensional Separated Flows Around a Sphere - Analysis of Vortex Chain Formation

1993 ◽  
pp. 27-30 ◽  
Author(s):  
U. Dallmann ◽  
H. Gebing ◽  
H. Vollmers
Keyword(s):  
Three Dimensional ◽  
Separated Flows ◽  
Chain Formation ◽  
Vortex Chain

scholarly journals Some chalcones derived from thiophene-3-carbaldehyde: synthesis and crystal structures

2019 ◽  
Vol 75 (7) ◽  
pp. 957-963 ◽  
Author(s):  
Trung Vu Quoc ◽  
Duong Tran Thi Thuy ◽  
Thuan Dang Thanh ◽  
Thanh Phung Ngoc ◽  
Vuong Nguyen Thien ◽  
...  
Keyword(s):  
Potassium Hydroxide ◽  
Thiophene Ring ◽  
Three Dimensional ◽  
Ethanol Solution ◽  
Molecular Structures ◽  
Chain Formation ◽  
Axis Direction ◽  
Crystal And Molecular Structures ◽  
Phenyl Rings ◽  
Thiophene Derivatives

The synthesis, spectroscopic data and crystal and molecular structures of four 3-(3-phenylprop-1-ene-3-one-1-yl)thiophene derivatives, namely 1-(4-hydroxyphenyl)-3-(thiophen-3-yl)prop-1-en-3-one, C13H10O2S, (1), 1-(4-methoxyphenyl)-3-(thiophen-3-yl)prop-1-en-3-one, C14H12O2S, (2), 1-(4-ethoxyphenyl)-3-(thiophen-3-yl)prop-1-en-3-one, C15H14O2S, (3), and 1-(4-bromophenyl)-3-(thiophen-3-yl)prop-1-en-3-one, C13H9BrOS, (4), are described. The four chalcones have been synthesized by reaction of thiophene-3-carbaldehyde with an acetophenone derivative in an absolute ethanol solution containing potassium hydroxide, and differ in the substituent at the para position of the phenyl ring: –OH for 1, –OCH3 for 2, –OCH2CH3 for 3 and –Br for 4. The thiophene ring in 4 was found to be disordered over two orientations with occupancies 0.702 (4) and 0.298 (4). The configuration about the C=C bond is E. The thiophene and phenyl rings are inclined by 4.73 (12) for 1, 12.36 (11) for 2, 17.44 (11) for 3 and 46.1 (6) and 48.6 (6)° for 4, indicating that the –OH derivative is almost planar and the –Br derivative deviates the most from planarity. However, the substituent has no real influence on the bond distances in the α,β-unsaturated carbonyl moiety. The molecular packing of 1 features chain formation in the a-axis direction by O—H...O contacts. In the case of 2 and 3, the packing is characterized by dimer formation through C—H...O interactions. In addition, C—H...π(thiophene) interactions in 2 and C—H...S(thiophene) interactions in 3 contribute to the three-dimensional architecture. The presence of C—H...π(thiophene) contacts in the crystal of 4 results in chain formation in the c-axis direction. The Hirshfeld surface analysis shows that for all four derivatives, the highest contribution to surface contacts arises from contacts in which H atoms are involved.

Development of Two-Dimensional Analogies Comformably to Three-Dimensional Separated Flows

1991 ◽  
pp. 365-368
Author(s):  
A. A. Zheltovodov ◽  
A. I. Maksimov ◽  
E. Kh. Shileyn ◽  
R. Dvořak ◽  
P. Šafařik
Keyword(s):  
Three Dimensional ◽  
Separated Flows ◽  
Two Dimensional

Control of separations in a highly loaded diffusion cascade by tailored boundary layer suction

2013 ◽  
Vol 228 (8) ◽  
pp. 1363-1374 ◽  
Author(s):  
Zhiyuan Cao ◽  
Bo Liu ◽  
Ting Zhang
Keyword(s):  
Boundary Layer ◽  
Static Pressure ◽  
Three Dimensional ◽  
Flow Fields ◽  
Separated Flows ◽  
Surface Boundary ◽  
Suction Surface ◽  
Surface Boundary Layer ◽  
Boundary Layer Suction ◽  
Highly Loaded

In order to explore the control mechanism of boundary layer suction on the separated flows of highly loaded diffusion cascades, a linear compressor cascade, which has separated flows on the whole span and three-dimensional separations over the suction surface/endwall corner, was investigated by tailored boundary layer suction. Three suction surface-slotted schemes and two combined suction surface/endwall-slotted schemes were designed. The original cascade and the cascade with part blade span suction were experimentally investigated on a high-subsonic cascade wind tunnel. In addition, numerical simulation was employed to study the flow fields of different suction schemes in detail. The results shows that while tailored boundary layer suction at part blade span can effectively remove the separations at the suction span, the flow fields of other spans deteriorated. The reasons are the ‘C’ shape or reverse ‘C’ shape spanwise distribution of static pressure after part blade span boundary layer suction. Suction surface boundary layer suction over the whole span can obviously eliminate the separation at the suction surface. However, because of the endwall boundary layer, suction surface boundary layer suction cannot effectively remove the corner three-dimensional separation. The separation over the whole span and the three-dimensional separation at the corner are completely eliminated by combined suction surface/endwall boundary layer suction. After combined boundary layer suction, the static pressure distribution over the blade span just like the shape of ‘C’ is good for the transport of the low-energy fluid near the endwall to the midspan.

Wall-normal-free Reynolds-stress closure for three-dimensional compressible separated flows

AIAA Journal ◽  
2001 ◽  
Vol 39 ◽  
pp. 1833-1842 ◽  
Author(s):  
G. A. Gerolymos ◽  
I. Vallet
Keyword(s):  
Reynolds Stress ◽  
Three Dimensional ◽  
Separated Flows

Predicting transition in two- and three-dimensional separated flows

2008 ◽  
Vol 29 (2) ◽  
pp. 504-526 ◽  
Author(s):  
L. Cutrone ◽  
P. De Palma ◽  
G. Pascazio ◽  
M. Napolitano
Keyword(s):  
Three Dimensional ◽  
Separated Flows

Brief Reviews of Some Time-Dependent Flows

1992 ◽  
Vol 114 (3) ◽  
pp. 283-298 ◽  
Author(s):  
T. Sarpkaya
Keyword(s):  
Three Dimensional ◽  
Separated Flows ◽  
Time Dependent ◽  
Circular Cylinders ◽  
Vortical Structures ◽  
Unsteady Separation ◽  
Flow Phenomena ◽  
Fundamental Research ◽  
The Subject ◽  
New Research

Separated flows in general and time-dependent flows in particular provide fertile territory for fundamental research in fluid dynamics and account for much of the subject matter. Thus, it is thought appropriate to review some of these unsteady flows with special emphasis on hydrodynamic applications which are, admittedly, of special interest to this writer: unsteady separation; characteristics of impulsively and nonimpulsively-started flow about cylinders; excursion of separation points on circular cylinders in oscillating flow; separation and other flow phenomena governing the unsteady maneuvers of large submerged bodies, and, finally, the three-dimensional footprints of subsurface vortical structures rising toward the free surface. It is hoped that these concise reviews will enhance communication between various groups of researchers, draw attention to many exciting phenomena in naval hydrodynamics, and inspire new research topics.

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