Numerical computation of the hypersonic rarefied flow near the sharpleading edge of a flat plate

1973 ◽  
Author(s):  
J. TANNEHILL ◽  
R. MOHLING ◽  
J. RAKICH
Keyword(s):  
Flat Plate ◽  
Numerical Computation ◽  
Rarefied Flow

PREDICTING CONTINUUM BREAKDOWN OF RAREFIED MICRO/NANO FLOWS USING ENTROPY AND ENTROPY GENERATION ANALYSIS

2013 ◽  
Vol 24 (05) ◽  
pp. 1350029 ◽  
Author(s):  
HAMID NIAZMAND ◽  
ALIREZA MOHAMMADZADEH ◽  
EHSAN ROOHI
Keyword(s):  
Shock Wave ◽  
Equilibrium State ◽  
Flat Plate ◽  
Entropy Production ◽  
Entropy Generation ◽  
Knudsen Number ◽  
Rarefied Flow ◽  
Rarefied Flows ◽  
Nonequilibrium Effects ◽  
Rarefaction Effects

In the current study, the DSMC method is utilized to obtain the entropy, entropy generation and the local gradient length Knudsen number in the rarefied flows. Two particular geometries, cavity and flat plate, are considered to study the departure from equilibrium state in the presence of sudden expansion/contraction, bend in the velocity profile, boundary flow and shock waves. The entire slip regime is considered to investigate small and large nonequilibrium effects on the entropy and entropy productions. Our investigation reveals that the distribution of entropy in the rarefied flow is very similar to the temperature contour. The entropy generation distribution in the micro cavity indicates that the two top corners are the regions around which departure from equilibrium state takes place. The study of entropy generation over the flat plate reveals that the entropy production is maximized along the shock wave. Moreover, increasing the rarefaction effects thickens the nonequilibrium shock wave. We also observed that increasing the nonequilibrium effects reduces the level of entropy generation in the rarefied flow. As the flow density decreases in the nonequilibrium regime, the level of shear stress and heat flux reduces, which subsequently lower the level of entropy generation in the rarefied flows. Furthermore, it was found that although the level of entropy generation in the flow reduces as the Knudsen number increases, the boundaries of the maximum entropy production region extends under large rarefaction effects.

Linear stability of a cylindrical falling film

1987 ◽  
Vol 183 ◽  
pp. 365-377 ◽  
Author(s):  
Francisco J. Solorio ◽  
Mihir Sen
Keyword(s):  
Reynolds Number ◽  
Flat Plate ◽  
Numerical Computation ◽  
Linear Stability ◽  
Weber Number ◽  
Perturbation Technique ◽  
Reynolds Numbers ◽  
Falling Film ◽  
Fully Developed Flow ◽  
Long Cylinder

The problem of a cylindrical falling film, descending vertically outside an infinitely long cylinder is considered. The linear stability of the fully developed flow is studied, first with a perturbation technique for small wavenumbers, and then by direct numerical computation. The numerical results are in agreement with other published values for the cylindrical jet and flat plate limits. The study shows that the cylindrical falling film is unstable for all Reynolds numbers, Weber numbers and radius ratios. Stability and amplification curves are calculated for different values of the parameters. With increasing curvature of the film the range of unstable wavenumbers and the wavenumber of the most amplified wave increase. For low curvature the wavenumber of the most amplified wave decreases with Reynolds number or Weber number, while for high curvatures it increases.

Numerical Computation of Nonstationary Aerodynamics of Flat Plate Cascades in Compressible Flow

1976 ◽  
Vol 98 (2) ◽  
pp. 165-170 ◽  
Author(s):  
R. H. Ni ◽  
F. Sisto
Keyword(s):  
Flat Plate ◽  
Numerical Computation ◽  
Compressible Flow ◽  
Computational Domain ◽  
Two Dimensional ◽  
Order Of Accuracy ◽  
Fluid Properties ◽  
Time Marching ◽  
Interblade Phase Angle ◽  
Good Agreement

The “time marching” technique is successfully applied to the numerical computation of the nonstationary aerodynamics of a flat plate cascade for compressible flow of either subsonic or supersonic nature. The unsteady perturbation amplitudes of fluid properties are used as the dependent variables so that the computational domain can be reduced to a two-dimensional channel guided by two adjacent blades for any interblade phase angle. A new method of handling the boundary condition is developed in which the order of accuracy for the boundary points will be the same as the interior points. The wake region behind the trailing edge of each blade is treated as a “slip plane” as done in two-dimensional steady state supersonic flow. Results are in good agreement with existing analytical solutions.

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