3,076 research outputs found
Stagnation point flow with radiation
Coupling between inviscid and viscid flows in hypersonic stagnation region investigated at high flight velocities with significant radiative heat transfe
Oscillatory oblique stagnation-point flow toward a plane wall
Two-dimensional oscillatory oblique stagnation-point flow toward a plane wall is investigated. The problem is a eneralisation of the steady oblique stagnation-point flow examined by previous workers. Far from the wall, the flow is composed of an irrotational orthogonal stagnation-point flow with a time-periodic strength, a simple shear flow of constant vorticity, and a time-periodic uniform stream. An exact solution of the Navier-Stokes equations is sought for which the flow streamfunction depends linearly on the coordinate parallel to the wall. The problem formulation reduces to a coupled pair of partial differential equations in time and one spatial variable. The first equation describes the oscillatory orthogonal stagnation-point flow discussed by previous workers. The second equation, which couples to the first, describes the oblique component of the flow. A description of the flow velocity field, the instantaneous streamlines, and the particle paths is sought through numerical solutions of the governing equations and via asymptotic analysis
MHD oblique stagnation-point flow of a Newtonian fluid
The steady two-dimensional oblique stagnation-point flow of
an electrically conducting Newtonian fluid in the presence of a uniform
external electromagnetic field (E0,
H0) is analyzed, and some physical
situations are examined. In particular, if E0 vanishes, H0 lies in the
plane of the flow, with a direction not parallel to the boundary, and
the induced magnetic field is neglected, it is proved that the oblique
stagnation-point flow exists if, and only if, the external magnetic field
is parallel to the dividing streamline. In all cases it is shown that the
governing nonlinear partial differential equations admit similarity solutions, and the resulting ordinary differential problems are solved numerically. Finally, the behaviour of the flow near the boundary is analyzed;
this depends on the Hartmann number if H0 is parallel to the dividing
streamline
MHD OBLIQUE STAGNATION-POINT FLOW OF A MICROPOLAR FLUID
The steady two-dimensional oblique stagnation-point flow of an electrically
conducting micropolar fluid in the presence of a uniform external electromagnetic field
(E0,H0) is analyzed and some physical situations are examined. In particular, if E0
vanishes, H0 lies in the plane of the flow, with a direction not parallel to the boundary,
and the induced magnetic field is neglected. It is proved that the oblique stagnationpoint
flow exists if, and only if, the external magnetic field is parallel to the dividing
streamline. In all cases it is shown that the governing nonlinear partial differential
equations admit similarity solutions and the resulting ordinary differential problems are
solved numerically. Finally, the behaviour of the flow near the boundary is analyzed;
this depends on the three dimensionless material parameters, and also on the Hartmann
number if H0 is parallel to the dividing streamline
Heat and mass transfer at a general three- dimensional stagnation point
Simultaneous effects of heat and mass transfer on boundary layer properties at three-dimensional stagnation point flow
MHD THREE-DIMENSIONAL STAGNATION-POINT FLOW OF A MICROPOLAR FLUID
The steady three-dimensional stagnation-point flow of an electrically conducting micropolar fluid in the absence and in the presence of a uniform external electromagnetic field (E0,H0) is analyzed and some physical situations are examined.
In particular, we proved that if we impress an external magnetic field H0, and we neglect the induced magnetic field, then
the steady MHD three-dimensional stagnation-point flow of such a fluid is possible if, and only if, H0 has the direction parallel to
one of the axes.
In all cases it is shown that the governing nonlinear partial differential equations admit similarity solutions. Moreover in the presence of an external magnetic field H0, it is found that the flow of a micropolar fluid has to satisfy
an ordinary differential problem whose solution depend on H0 through the Hartmann number M.
Finally, the skin-friction components along the axes are computed
Cavitation phenomena in a stagnation point flow
Cavitation phenomena inherently occur in regions with low pressure. Consequently, it seems unlikely that cavitation would develop near the stagnation point of a blunt body flow. However, in recent experiments involving a high-speed bubbly jet impinging on a blunt body, we have observed substantial rapid growth and stretching of bubbles near the stagnation point over a wide range of flow parameters. Using a highspeed camera we observe that bubbles with initial diameters of tens of microns located very close to the blunt body are being stretched into long strings that are generally aligned parallel to the body surface. In-line Digital Holographic Microscopy (DHM) measurements show that the bubble strings are located far from the walls. High resolution 3-D holographic Particle Image Velocimetry (DHM-PIV) is performed to quantify the 3-D flow field near the leading edge of the blunt body. Instantaneous data show vortices being stretched by the local strain field close to the blunt body in an orientation consistent with the appearance of cavitation. These vortices are originated from the turbulent jet upstream. An estimate based on the measured vortex strength and strain field shows that stretching rapidly decreases the pressure in the vortex core below the vapor pressure, explaining the occurrence of cavitation.http://deepblue.lib.umich.edu/bitstream/2027.42/84222/1/CAV2009-final179.pd
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