Vortex sound in the presence of a wedge with inhomogeneous surface flow impedance

2005 ◽  
Vol 281 (3-5) ◽  
pp. 1077-1091 ◽  
Author(s):  
S.K. Tang ◽  
C.K. Lau
Keyword(s):  
Surface Flow ◽  
Inhomogeneous Surface ◽  
Vortex Sound ◽  
Flow Impedance

Flow instabilities in thermocapillary-buoyant liquid pools

2010 ◽  
Vol 644 ◽  
pp. 509-535 ◽  
Author(s):  
H. C. KUHLMANN ◽  
U. SCHOISSWOHL
Keyword(s):  
Prandtl Number ◽  
Rotational Symmetry ◽  
Radial Profile ◽  
Axisymmetric Flow ◽  
Surface Flow ◽  
Return Flow ◽  
Toroidal Vortex ◽  
Inhomogeneous Surface ◽  
Centrifugal Instability ◽  
Prandtl Numbers

The linear stability of the incompressible axisymmetric flow in a buoyant-thermocapillary liquid pool is considered which is heated from above by a heat flux with a parabolic radial profile. Buoyancy forces and radial thermocapillary stresses due to the inhomogeneous surface temperature distribution drive a toroidal vortex. In the absence of buoyancy and for low Prandtl numbers the basic flow becomes unstable typically by a stationary centrifugal instability. At moderate Prandtl numbers the rotational symmetry is broken by hydrothermal waves. In the limit of vanishing Prandtl number two other critical modes are found if the pool is very shallow. One mode is a centrifugally destabilized rotating wave with high azimuthal wavenumber. The other mode is steady and it is driven by the deceleration of the radial inward return flow as it approaches the axis. The deceleration results from an entrainment of fluid into the thin layer of rapid radial outward surface flow. The centrifugal instability of the toroidal vortex flow is assisted by buoyancy in the low-Prandtl-number limit, because the cooling from the sidewall augments the thermocapillary driving. For moderately high Prandtl numbers a stable thermal stratification suppresses the hydrothermal-wave instabilities.

IDENTIFYING THE MOST SUITABLE AREAS FOR SURFACE FLOW WETLAND CONSTRUCTION IN LITHUANIA

2015 ◽  
Author(s):  
Antanas DUMBRAUSKAS ◽  
Nijolė BASTIENĖ ◽  
Petras PUNYS
Keyword(s):  
Constructed Wetlands ◽  
Ecological Status ◽  
Surface Flow ◽  
Gis Analysis ◽  
Proximity Analysis ◽  
Wetland Construction ◽  
The Mean ◽  
Two Phases ◽  
Terrain Features ◽  
Surface Flow Constructed Wetlands

GIS-based approach to find the suitable sites for surface flow constructed wetlands was employed for the Lithuanian river basins with low ecological status. According to the nature of the analysed criteria the flowchart consists of two phases. Criteria used include hydrographical network, soil properties, terrain features, land use, etc. Some of them have strictly defined values (constraints), and other ranges within certain limits (factors). Limited criteria were analysed using rejection principle and influencing factors using proximity analysis and overlay methods. Selecting the potential sites using standard GIS analysis tools there was estimated about 3286 sites for possible wetlands with the mean area of inflow basin about 4 km2 in the basins of water bodies at risk.

The efficiency of application of virtual cross-sections method and hypotheses MELS in problems of wave signal propagation in elastic waveguides with rough surfaces

2016 ◽  
pp. 3564-3575 ◽  
Author(s):  
Ara Sergey Avetisyan
Keyword(s):  
Half Space ◽  
Cross Sections ◽  
Classical Method ◽  
Signal Propagation ◽  
Elastic Half Space ◽  
Layered Systems ◽  
Surface Layers ◽  
Inhomogeneous Surface ◽  
Wave Signal ◽  
The Impact

The efficiency of virtual cross sections method and MELS (Magneto Elastic Layered Systems) hypotheses application is shown on model problem about distribution of wave field in thin surface layers of waveguide when plane wave signal is propagating in it. The impact of surface non-smoothness on characteristics of propagation of high-frequency horizontally polarized wave signal in isotropic elastic half-space is studied. It is shown that the non-smoothness leads to strong distortion of the wave signal over the waveguide thickness and along wave signal propagation direction as well.  Numerical comparative analysis of change in amplitude and phase characteristics of obtained wave fields against roughness of weakly inhomogeneous surface of homogeneous elastic half-space surface is done by classical method and by proposed approach for different kind of non-smoothness.

Measurement of surface flow features at the stagnation region of a swept cylinder

1994 ◽  
Author(s):  
S. Mangalam ◽  
S. Venkateswaran ◽  
S. Korategere
Keyword(s):  
Surface Flow ◽  
Stagnation Region ◽  
Flow Features
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