Measurement of a three-dimensional hypersonic density field

1992 ◽  
Author(s):  
STEVE DOERR
Keyword(s):  
Three Dimensional ◽  
Density Field

scholarly journals Numerical study on snow transport and drift formation

1993 ◽  
Vol 18 ◽  
pp. 135-141 ◽  
Author(s):  
Takahiko Uematsu
Keyword(s):  
Continuity Equation ◽  
Numerical Study ◽  
Three Dimensional ◽  
Flow Simulation ◽  
Density Field ◽  
Particle Movement ◽  
Snow Density ◽  
Fall Velocity ◽  
Snow Transport ◽  
Good Agreement

A three-dimensional, numerical simulation model for snow transport and drift formation is proposed in which saltation as well as suspension are considered as dynamic behavioral factors of moving snow particles. The procedure for simulation is as follows: (1) Air flow field is simulated solving the Reynolds equations and the continuity equation. (2) Using the result of the air field flow simulation, the blown-snow density field is simulated using the diffusion equations in which the fall velocity of blown snow particles is considered. In the boundary conditions, the particle movement of saltation is taken into consideration. (3) Finally, the snowdrift rate is computed based on the amount of snow particles not transported by saltation. This model was quantitatively tested for the phenomenon of snowdrift development. The computed results showed good agreement with observations.

A Three Dimensional Density Field Measurement of Transonic Flow From a Square Nozzle Using Holographic Interferometry

1977 ◽  
Vol 99 (4) ◽  
pp. 737-743 ◽  
Author(s):  
L. T. Clark ◽  
D. C. Koepp ◽  
J. J. Thykkuttathil
Keyword(s):  
Holographic Interferometry ◽  
Transonic Flow ◽  
Ambient Pressure ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Density Field ◽  
Technical Improvement ◽  
Potential Core ◽  
Core Part ◽  
Accurate Experimental Data

The three dimensional static density field was measured for transonic flow from a square nozzle using holographic interferometry. These measurements are presented in order to show the efficiency of this method for obtaining accurate experimental data of transonic flows. The accuracy of the measurement was estimated by operating the nozzle at a pressure ratio of 1.89 where the flow should expand to the ambient pressure with no afterexpansion effects. The standard deviation in the static density was approximately 1 percent over the isentropic (potential core) part of the flow. Data are also presented for a pressure ratio of 2.14 where afterexpansion effects are important. The method described represents a significant technical improvement in practical interferometry.

Quantitative Determination of Three-Dimensional Density Field by Holographic Interferometry

AIAA Journal ◽  
1975 ◽  
Vol 13 (7) ◽  
pp. 841-842 ◽  
Author(s):  
Tse-Fou Zien ◽  
William C. Ragsdale ◽  
W. Charles Spring
Keyword(s):  
Quantitative Determination ◽  
Holographic Interferometry ◽  
Three Dimensional ◽  
Density Field

scholarly journals Three-dimensional density measurements of a heated jet using laser-speckle tomographic background-oriented schlieren

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Shoaib Amjad ◽  
Julio Soria ◽  
Callum Atkinson
Keyword(s):  
Refractive Index ◽  
Turbulent Flows ◽  
Measurement Techniques ◽  
Three Dimensional ◽  
Density Field ◽  
Laser Speckle ◽  
Spatial Density ◽  
Reference Image ◽  
Mixing Processes ◽  
Background Oriented Schlieren

Three-dimensional density field measurement techniques can be used to understand the complex heat transfer and mixing processes that occur in turbulent flows. Tomographic background-oriented schlieren (BOS) is an optical technique that can be used to measure the instantaneous three-dimensional density field in turbulent flows. Light rays propagating through the flow are deflected from their ambient path due to variations in refractive index related to the spatial density gradients. In BOS, a camera is placed looking through the flow at a reference image, which captures path-integrated information on the refractive index gradients in the form of apparent image displacements Richard and Raffel (2001). The displacements recorded simultaneously from many cameras placed around the flow form the basis of a tomographic reconstruction of the three-dimensional refractive index gradients Goldhahn and Seume (2007), from which the density field is obtained through integration of the gradients and application of the Gladstone-Dale relation.

scholarly journals Direct Observations of Along-Isopycnal Upwelling and Diapycnal Velocity at a Shelfbreak Front*

2004 ◽  
Vol 34 (3) ◽  
pp. 543-565 ◽  
Author(s):  
John A. Barth ◽  
Dave Hebert ◽  
Andrew C. Dale ◽  
David S. Ullman
Keyword(s):  
Three Dimensional ◽  
Internal Tide ◽  
Acoustic Doppler Current Profiler ◽  
Density Field ◽  
Strong Mixing ◽  
Optical Fields ◽  
Direct Observations ◽  
Current Profiler ◽  
Southern Flank ◽  
Coastal Front

Abstract By mapping the three-dimensional density field while simultaneously tracking a subsurface, isopycnal float, direct observations of upwelling along a shelfbreak front were made on the southern flank of Georges Bank. The thermohaline and bio-optical fields were mapped using a towed undulating vehicle, and horizontal velocity was measured with a shipboard acoustic Doppler current profiler. A subsurface isopycnal float capable of measuring diapycnal flow past the float was acoustically tracked from the ship. The float was released near the foot of the shelfbreak front (95–100-m isobath) and moved 15 km seaward as it rose from 80 to 50 m along the sloping frontal isopycnals over a 2-day deployment. The float's average westward velocity was 0.09 m s−1, while a drifter drogued at 15 m released at the same location moved westward essentially alongfront at 0.18 m s−1. The float measured strong downward vertical velocities (in excess of 0.02 m s−1) associated with propagation of internal tidal solibores in the onbank direction from their formation near the shelf break. The float measured large upward vertical velocities (in excess of 0.001 m s−1 ≃ 100 m day−1) as the pycnocline rebounded adiabatically after the passage of the internal tide solibore. The directly measured mean along-isopycnal vertical velocity was 17.5 m day−1. Intense mixing events lasting up to 2 hours were observed in the shelfbreak front at the boundary between cold, fresh shelf water and warm, salty slope water. Diapycnal velocities of up to 3 × 10−3 m s−1 were measured, implying a diapycnal thermal diffusivity as large as 10−2 m2 s−1, indicative of strong mixing events in this coastal front.

Three-Dimensional Varying Density Field Plate for Lateral Power Devices

2019 ◽  
Vol 66 (3) ◽  
pp. 1422-1429 ◽  
Author(s):  
Chunwei Zhang ◽  
Yang Li ◽  
Wenjing Yue ◽  
Zhiming Li ◽  
Xiaoqian Fu ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Density Field ◽  
Power Devices ◽  
Field Plate
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