S0502-2-3 Study on the Flow Characteristics of Two-Dimensional Synthetic Jets

2010 ◽  
Vol 2010.2 (0) ◽  
pp. 159-160
Author(s):  
Koichi NISHIBE ◽  
Yuki FUJITA ◽  
Kotaro SATO ◽  
Kazuhiko YOKOTA ◽  
Toru KOSO
Keyword(s):  
Flow Characteristics ◽  
Synthetic Jets ◽  
Two Dimensional

Effect of Compressibility on Gaseous Flows in a Micro-Tube

2003 ◽  
Author(s):  
Yutaka Asako ◽  
Kenji Nakayama
Keyword(s):  
Reynolds Number ◽  
Mach Number ◽  
Pressure Distribution ◽  
Flow Characteristics ◽  
Fused Silica ◽  
Two Dimensional ◽  
Arbitrary Lagrangian Eulerian ◽  
Gaseous Flow ◽  
Gaseous Flows ◽  
Energy Equations

The product of friction factor and Reynolds number (f·Re) of gaseous flow in the quasi-fully developed region of a micro-tube was obtained experimentally and numerically. The tube cutting method was adopted to obtain the pressure distribution along the tube. The fused silica tubes whose nominal diameters were 100 and 150 μm, were used. Two-dimensional compressible momentum and energy equations were solved to obtain the flow characteristics in micro-tubes. The numerical methodology is based on the Arbitrary-Lagrangian-Eulerian (ALE) method. The both results agree well and it was found that (f·Re) is a function of Mach number.

A finite-element model of oxygen diffusion in the pulmonary capillaries

1997 ◽  
Vol 82 (6) ◽  
pp. 2036-2044 ◽  
Author(s):  
Andreas O. Frank ◽  
C. J. Charles Chuong ◽  
Robert L. Johnson
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Oxygen Diffusion ◽  
Flow Characteristics ◽  
Element Model ◽  
Two Dimensional ◽  
Plasma Protein Concentration ◽  
Pulmonary Capillaries ◽  
Dimensional Finite Element ◽  
Barrier Surface

Frank, Andreas O., C. J. Charles Chuong, and Robert L. Johnson. A finite-element model of oxygen diffusion in the pulmonary capillaries. J. Appl. Physiol. 82(6): 2036–2044, 1997.—We determined the overall pulmonary diffusing capacity (Dl) and the diffusing capacities of the alveolar membrane (Dm) and the red blood cell (RBC) segments (De) of the diffusional pathway for O2 by using a two-dimensional finite-element model developed to represent the sheet-flow characteristics of pulmonary capillaries. An axisymmetric model was also considered to assess the effect of geometric configuration. Results showed the membrane segment contributing the major resistance, with the RBC segment resistance increasing as O2 saturation ([Formula: see text]) rises during the RBC transit: RBC contributed 7% of the total resistance at the capillary inlet ([Formula: see text] = 75%) and 30% toward the capillary end ([Formula: see text] = 95%) for a 45% hematocrit (Hct). Both Dm and Dlincreased as the Hct increased but began approaching a plateau near an Hct of 35%, due to competition between RBCs for O2 influx. Both Dm and Dl were found to be relatively insensitive (2∼4%) to changes in plasma protein concentration (28∼45%). Axisymmetric results showed similar trends for all Hct and protein concentrations but consistently overestimated the diffusing capacities (∼2.2 times), primarily because of an exaggerated air-tissue barrier surface area. The two-dimensional model correlated reasonably well with experimental data and can better represent the O2 uptake of the pulmonary capillary bed.

Study on the Flow Characteristics of Synthetic Jets Near a Rigid Plane Boundary

2011 ◽  
Author(s):  
Ryota Tsunoda ◽  
Koichi Nishibe ◽  
Yuki Fujita ◽  
Kotaro Sato ◽  
Kazuhiko Yokota ◽  
...  
Keyword(s):  
Flow Characteristics ◽  
Maximum Velocity ◽  
Stokes Number ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Plane Boundary ◽  
Jet Flows ◽  
Rigid Boundary ◽  
Wire Method ◽  
Rigid Plane

The jet flows have been applied to various fields to control the flow separation. Over the last decade, several studies have investigated synthetic jets. However, there are still many clarifications needed, including details of the structure and Coanda effect of synthetic jets. The present study clarifies some fundamental flow characteristics of free synthetic jets and synthetic jets near a rigid boundary by conducting an experiment and numerical simulations. As the main results, it is found that the velocity distribution of free synthetic jets depends on K = Re/S2 (the ratio of the Reynolds number to the square of the Stokes number) and can be identified by the maximum velocity at the centerline and the jet half-width. Flow visualization is carried out applying the smoke wire method. In addition, it is confirmed that the flow characteristics of the synthetic jet near a rigid boundary and re-attachment length of the synthetic jet are determined not only by H1/b0 (normalized step heights) but also K.

scholarly journals Numerical Study of Flow Characteristics Around Confined Cylinder using OpenFOAM

2018 ◽  
Vol 7 (4.35) ◽  
pp. 617
Author(s):  
P. Mathupriya ◽  
L. Chan ◽  
H. Hasini ◽  
A. Ooi
Keyword(s):  
Reynolds Number ◽  
Vortex Shedding ◽  
Numerical Study ◽  
Vortex Formation ◽  
Plane Channel ◽  
Flow Characteristics ◽  
Strong Interactions ◽  
Two Dimensional ◽  
Computational Fluid Dynamics Cfd ◽  
Shedding Frequency

The numerical study of the flow over a two-dimensional cylinder which is symmetrically confined in a plane channel is presented to study the characteristics of vortex shedding. The numerical model has been established using direct numerical simulation (DNS) based on the open source computational fluid dynamics (CFD) code named OpenFOAM. In the present study, the flow fields have been computed at blockage ratio, β of 0.5 and at Reynolds number, Re of 200 and 300. Two-dimensional simulations investigated on the effects of Reynolds number based on the vortex formation and shedding frequency. It was observed that the presence of two distinct shedding frequencies appear at higher Reynolds number due to the confinement effects where there is strong interactions between boundary layer, shear layer and the wake of the cylinder. The range of simulations conducted here has shown to produce results consistent with that available in the open literature. Therefore, OpenFOAM is found to be able to accurately capture the complex physics of the flow.

scholarly journals A Two-Dimensional Study of Transonic Flow Characteristics in Steam Control Valve for Power Plant

2010 ◽  
Vol 3 (1) ◽  
pp. 58-66
Author(s):  
Koichi Yonezawa ◽  
Yoshinori Terachi ◽  
Toru Nakajima ◽  
Yoshinobu Tsujimoto ◽  
Kenichi Tezuka ◽  
...  
Keyword(s):  
Power Plant ◽  
Transonic Flow ◽  
Flow Characteristics ◽  
Control Valve ◽  
Two Dimensional

scholarly journals Flow Characteristics of Conservative Two-dimensional Inclined Thermals

1996 ◽  
Vol 40 ◽  
pp. 549-554
Author(s):  
Juichiro AKIYAMA ◽  
Masaru URA ◽  
Shunichiro SAITO
Keyword(s):  
Flow Characteristics ◽  
Two Dimensional

An Experimental and Analytical Investigation of Rectangular Synthetic Jets

2009 ◽  
Vol 131 (12) ◽  
Author(s):  
Gopi Krishnan ◽  
Kamran Mohseni
Keyword(s):  
Flow Field ◽  
Turbulent Jets ◽  
Velocity Profiles ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Empirical Modeling ◽  
Transition To Turbulence ◽  
Two Dimensional ◽  
Limited Region ◽  
Velocity Decay

In this paper the flow field of a rectangular synthetic jet driven by a piezoelectric membrane issuing into a quiescent environment is studied. The similarities exhibited by synthetic and continuous turbulent jets lead to the hypothesis that a rectangular synthetic jet within a limited region downstream of the orifice be modeled using similarity analysis just as a continuous planar jet. Accordingly, the jet is modeled using the classic two-dimensional solution to a continuous jet, where the virtual viscosity coefficient of the continuous turbulent jet is replaced with that measured for a synthetic jet. The virtual viscosity of the synthetic jet at a particular axial location is related to the spreading rate and velocity decay rate of the jet. Hot-wire anemometry is used to characterize the flow downstream of the orifice. The flow field of rectangular synthetic jets is thought to consist of four regions as distinguished by the centerline velocity decay. The regions are the developing, the quasi-two-dimensional, the transitional, and the axisymmetric regions. It is in the quasi-two-dimensional region that the planar model applies, and where indeed the jet exhibits self-similar behavior as distinguished by the collapse of the lateral time average velocity profiles when scaled. Furthermore, within this region the spanwise velocity profiles display a saddleback profile that is attributed to the secondary flow generated at the smaller edges of the rectangular orifice. The scaled spreading and decay rates are seen to increase with stroke ratio and be independent of Reynolds number. However, the geometry of the actuator is seen to additionally affect the external characteristics of the jet. The eddy viscosities of the synthetic jets under consideration are shown to be larger than equivalent continuous turbulent jets. This enhanced eddy viscosity is attributed to the additional mixing brought about by the introduction of the periodic vortical structures in synthetic jets and their ensuing break down and transition to turbulence. Further, a semi-empirical modeling approach is proposed, the final objective of which is to obtain a functional relationship between the parameters that describe the external flow field of the synthetic jet and the input operational parameters to the system.

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