Density and velocity fields in collisionless flow past a diffusely reflecting cone

1970 ◽  
Vol 48 (13) ◽  
pp. 1628-1631
Author(s):  
James Parker Elliott
Keyword(s):  
Flow Field ◽  
Free Stream ◽  
Angle Of Attack ◽  
Velocity Fields ◽  
Circular Cone ◽  
Two Dimensional ◽  
Transition Flow ◽  
Flow Past ◽  
Monatomic Gas

Results of flow field calculations for the collisionless flow of a neutral, monatomic gas past a diffusely reflecting right circular cone at zero angle of attack with the free stream are presented. Singularities at the vertex and at the shoulder of the base are illustrated and discussed. Comparison is made with similar results for spheres and two-dimensional polygonal bodies and with results for transition flow past sharp cones. Methods for improving the analysis are suggested.

Accelerated flow past a symmetric aerofoil: experiments and computations

2007 ◽  
Vol 591 ◽  
pp. 255-288 ◽  
Author(s):  
T. K. SENGUPTA ◽  
T. T. LIM ◽  
SHARANAPPA V. SAJJAN ◽  
S. GANESH ◽  
J. SORIA
Keyword(s):  
Reynolds Number ◽  
Flow Field ◽  
Angle Of Attack ◽  
Stream Velocity ◽  
Published Data ◽  
Navier Stokes Equation ◽  
Moment Coefficient ◽  
Flow Past ◽  
Naca 0015 ◽  
Accelerated Flow

Accelerated flow past a NACA 0015 aerofoil is investigated experimentally and computationally for Reynolds number Re = 7968 at an angle of attack α = 30°. Experiments are conducted in a specially designed piston-driven water tunnel capable of producing free-stream velocity with different ramp-type accelerations, and the DPIV technique is used to measure the resulting flow field past the aerofoil. Computations are also performed for other published data on flow past an NACA 0015 aerofoil in the range 5200 ≤ Re ≤ 35000, at different angles of attack. One of the motivations is to see if the salient features of the flow captured experimentally can be reproduced numerically. These computations to solve the incompressible Navier–Stokes equation are performed using high-accuracy compact schemes. Load and moment coefficient variations with time are obtained by solving the Poisson equation for the total pressure in the flow field. Results have also been analysed using the proper orthogonal decomposition technique to understand better the evolving vorticity field and its dependence on Reynolds number and angle of attack. An energy-based stability analysis is performed to understand unsteady flow separation.

Two-Dimensional Experimental Investigation on the Effects of a Fowler Flap Gap and Overlap Size on the Wake Flow Field

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
David Demel ◽  
Mohsen Ferchichi ◽  
William D. E. Allan ◽  
Marouen Dghim
Keyword(s):  
Experimental Investigation ◽  
Flow Field ◽  
Angle Of Attack ◽  
Wake Flow ◽  
Two Dimensional ◽  
Edge Region ◽  
Suction Surface ◽  
Trailing Edge ◽  
Piv Measurements ◽  
Image Velocimetry

This work details an experimental investigation on the effects of the variation of flap gap and overlap sizes on the flow field in the wake of a wing-section equipped with a trailing edge Fowler flap. The airfoil was based on the NACA 0014-1.10 40/1.051 profile, and the flap was deployed with 40 deg deflection angle. Two-dimensional (2D) particle image velocimetry (PIV) measurements of the flow field in the vicinity of the main wing trailing edge and the flap region were performed for the optimal flap gap and overlap, as well as for flap gap and overlap increases of 2% and 4% chord beyond optimal, at angles of attack of 0 deg, 10 deg, and 12 deg. For all the configurations investigated, the flow over the flap was found to be fully stalled. At zero angle of attack, increasing the flap gap size was found to have minor effects on the flow field but increased flap overlap resulted in misalignment between the main wing boundary layer (BL) flow and the slot flow that forced the flow in the trailing edge region of the main wing to separate. When the angle of attack was increased to near stall conditions (at angle of attack of 12 deg), increasing the flap gap was found to energize and improve the flow in the trailing edge region of the main wing, whereas increased flap overlap further promoted flow separation on the main wing suction surface possibly steering the wing into stall.

scholarly journals Acquisition of a 3 min, two-dimensional glacier velocity field with terrestrial radar interferometry

2017 ◽  
Vol 63 (240) ◽  
pp. 629-636 ◽  
Author(s):  
DENIS VOYTENKO ◽  
TIMOTHY H. DIXON ◽  
DAVID M. HOLLAND ◽  
RYAN CASSOTTO ◽  
IAN M. HOWAT ◽  
...  
Keyword(s):  
Velocity Field ◽  
Flow Field ◽  
Feature Tracking ◽  
High Spatial Resolution ◽  
Velocity Fields ◽  
Radar Interferometry ◽  
Line Of Sight ◽  
Two Dimensional ◽  
Outlet Glacier ◽  
Glacier Velocity

ABSTRACTOutlet glaciers undergo rapid spatial and temporal changes in flow velocity during calving events. Observing such changes requires both high temporal and high spatial resolution methods, something now possible with terrestrial radar interferometry. While a single such radar provides line-of-sight velocity, two radars define both components of the horizontal flow field. To assess the feasibility of obtaining the two-dimensional (2-D) flow field, we deployed two terrestrial radar interferometers at Jakobshavn Isbrae, a major outlet glacier on Greenland's west coast, in the summer of 2012. Here, we develop and demonstrate a method to combine the line-of-sight velocity data from two synchronized radars to produce a 2-D velocity field from a single (3 min) interferogram. Results are compared with the more traditional feature-tracking data obtained from the same radar, averaged over a longer period. We demonstrate the potential and limitations of this new dual-radar approach for obtaining high spatial and temporal resolution 2-D velocity fields at outlet glaciers.

Study of three-dimensional unsteady Oseen flow

1978 ◽  
Vol 86 (4) ◽  
pp. 609-622 ◽  
Author(s):  
S. Murata ◽  
Y. Miyake ◽  
Y. Tsujimoto ◽  
F. Yamamoto
Keyword(s):  
Flow Field ◽  
External Force ◽  
Three Dimensional ◽  
Velocity Fields ◽  
Applied Force ◽  
Two Dimensional ◽  
Uniform Velocity ◽  
Pressure Fields ◽  
Oseen Flow ◽  
Impulsive Pressure

In the present paper, it is intended to give the elementary solutions of three-dimensional unsteady Oseen flow when unsteady concentrated lift and/or drag is applied in the flow field. It is shown that the pressure fields due to concentrated impulsive lift and/or drag can be represented by an impulsive pressure doublet in the direction of the applied force and the corresponding velocity fields by diffusing free doublets in the direction of the external force that are shed from the location of the force application and convected downstream with otherwise uniform velocity. It is also confirmed that combination of the elementary solutions given in the present paper yields the two-dimensional ones.

The Actuator Surface Model: A New Navier–Stokes Based Model for Rotor Computations

2009 ◽  
Vol 131 (1) ◽  
Author(s):  
Wen Zhong Shen ◽  
Jian Hui Zhang ◽  
Jens Nørkær Sørensen
Keyword(s):  
Wind Turbine ◽  
Numerical Technique ◽  
Angle Of Attack ◽  
Vertical Axis ◽  
Navier Stokes ◽  
Surface Model ◽  
Two Dimensional ◽  
Vertical Axis Wind Turbine ◽  
Flow Past ◽  
Surface Technique

This paper presents a new numerical technique for simulating two-dimensional wind turbine flow. The method, denoted as the 2D actuator surface technique, consists of a two-dimensional Navier–Stokes solver in which the pressure distribution is represented by body forces that are distributed along the chord of the airfoils. The distribution of body force is determined from a set of predefined functions that depend on angle of attack and airfoil shape. The predefined functions are curve fitted using pressure distributions obtained either from viscous-inviscid interactive codes or from full Navier–Stokes simulations. The actuator surface technique is evaluated by computing the two-dimensional flow past a NACA 0015 airfoil at a Reynolds number of 106 and an angle of attack of 10deg and by comparing the computed streamlines with the results from a traditional Reynolds-averaged Navier–Stokes computation. In the last part, the actuator surface technique is applied to compute the flow past a two-bladed vertical axis wind turbine equipped with NACA 0012 airfoils. Comparisons with experimental data show an encouraging performance of the method.

Computational analysis of the flow field structure of a non-reacting hypersonic flow over forward-facing steps

2014 ◽  
Vol 763 ◽  
pp. 460-499 ◽  
Author(s):  
P. H. M. Leite ◽  
W. F. N. Santos
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Hypersonic Flow ◽  
Field Structure ◽  
Recirculation Region ◽  
Transition Flow ◽  
Face Surface ◽  
Face Height ◽  
Flow Past ◽  
Forward Facing Step

AbstractThis work is a computational study of a rarefied non-reacting hypersonic flow past a forward-facing step at zero-degree angle of attack in thermal non-equilibrium. Effects on the flow field structure and on the aerodynamic surface quantities due to changes in step frontal-face height are investigated by employing the direct simulation Monte Carlo method. The work focuses the attention of designers of hypersonic configurations on the fundamental parameter of surface discontinuity, which can have an important impact on even initial design. The results presented highlight the sensitivity of the primary flow field properties, velocity, density, pressure and temperature, to changes in the step frontal-face height. In addition, the behaviour of heat transfer, pressure and skin friction coefficients with variation of the step frontal-face height is detailed. The analysis shows that hypersonic flow past a forward-facing step in the transition flow regime is characterized by a strong compression ahead of the frontal face, which influences the aerodynamic surface properties upstream and adjacent to the frontal face. The analysis also shows that the extension of the upstream disturbance depends on the step frontal-face height. It was found that the recirculation region ahead of the step is also a function of the frontal-face height. A sequence of Moffatt eddies of decreasing size and intensity is observed in the concave step corner. Locally high heating and pressure loads were observed at three locations along the surface, i.e. on the lower surface, on the frontal face and on the upper surface. The results showed that both loads rely on the frontal-face height. The peak values for the heat transfer coefficient on the frontal-face surface were at least one order of magnitude larger than the maximum value observed for a smooth surface, i.e. a flat plate without a step. A comparison of the present simulation results with numerical and experimental data showed close agreement concerning the wall pressure acting on the step surface.

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