Step-induced turbulence in a high-velocity boundary layer

1989 ◽  
Vol 24 (1) ◽  
pp. 150-153
Author(s):  
V. Ya. Kiselev ◽  
V. I. Lysenko
Keyword(s):  
Boundary Layer ◽  
High Velocity ◽  
Velocity Boundary Layer

A New Method to Measure Prandtl Number and Thermal Conductivity of Fluids

1957 ◽  
Vol 24 (1) ◽  
pp. 25-28
Author(s):  
E. R. G. Eckert ◽  
T. F. Irvine
Keyword(s):  
Thermal Conductivity ◽  
Boundary Layer ◽  
Prandtl Number ◽  
High Velocity ◽  
Atmospheric Pressure ◽  
New Method ◽  
Test Results ◽  
Test Setup ◽  
Velocity Boundary Layer ◽  
Layer Flow

Abstract A new method is described by which the Prandtl number and indirectly the thermal conductivity of fluids can be measured. The method is based on the fact that a well-established, unique relation exists between the Prandtl number and the recovery factor for laminar high-velocity boundary-layer flow. The test setup is described which has been devised for such measurements, and test results are presented for air at atmospheric pressure and temperatures between 60 and 350 F.

Effect of boundary-layer removal on high velocity flame stabilization

AIAA Journal ◽  
1964 ◽  
Vol 2 (11) ◽  
pp. 2030-2031
Author(s):  
JAMES R. MAUS ◽  
WILLIAM T. SNYDER
Keyword(s):  
Boundary Layer ◽  
High Velocity ◽  
Flame Stabilization ◽  
Layer Removal

Exponentially Decaying Heat Source on MHD Tangent Hyperbolic Two-Phase Flows over a Flat Surface with Convective Conditions

2018 ◽  
Vol 387 ◽  
pp. 286-295 ◽  
Author(s):  
S.U. Mamatha ◽  
Chakravarthula S.K. Raju ◽  
Putta Durga Prasad ◽  
K.A. Ajmath ◽  
Mahesha ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Differential Equations ◽  
Heat Source ◽  
Thermal Boundary Layer ◽  
Energy Transport ◽  
Weissenberg Number ◽  
Dust Particles ◽  
Convective Conditions ◽  
Two Phase ◽  
Velocity Boundary Layer

The present framework addresses Darcy-Forchheimer steady incompressible magneto hydrodynamic hyperbolic tangent fluid with deferment of dust particles over a stretching surface along with exponentially decaying heat source. To control the thermal boundary layer Convective conditions are considered. Appropriate transformations were utilized to convert partial differential equations (PDEs) into nonlinear ordinary differential equations (NODEs). To present numerical approximations Runge-Kutta Fehlberg integration is implemented. Computational results of the flow and energy transport are interpreted for both fluid and dust phase with the support of graph and table illustrations. It is found that non-uniform inertia coefficient of porous medium decreases velocity boundary layer thickness and enhances thermal boundary layer. Improvement in Weissenberg number improves the velocity boundary layer and declines the thermal boundary layer.

Rayleigh number scaling in numerical convection

1996 ◽  
Vol 310 ◽  
pp. 139-179 ◽  
Author(s):  
Robert M. Kerr
Keyword(s):  
Boundary Layer ◽  
Rayleigh Number ◽  
Large Scale ◽  
Stokes Equations ◽  
Good Evidence ◽  
Navier Stokes ◽  
Fixed Temperature ◽  
Navier Stokes Equations ◽  
Local Boundary ◽  
Velocity Boundary Layer

Using direct simulations of the incompressible Navier-Stokes equations with rigid upper and lower boundaries at fixed temperature and periodic sidewalls, scaling with respect to Rayleigh number is determined. At large aspect ratio (6:6:1) on meshes up to 288 × 288 × 96, a single scaling regime consistent with the properties of ‘hard’ convective turbulence is found for Pr = 0.7 between Ra = 5 × 104 and Ra = 2 × 107. The properties of this regime include Nu ∼ RaβT with βT = 0.28 ≈ 2/7, exponential temperature distributions in the centre of the cell, and velocity and temperature scales consistent with experimental measurements. Two velocity boundary-layer thicknesses are identified, one outside the thermal boundary layer that scales as Ra−1/7 and the other within it that scales as Ra−3/7. Large-scale shears are not observed; instead, strong local boundary-layer shears are observed in regions between incoming plumes and an outgoing network of buoyant sheets. At the highest Rayleigh number, there is a decade where the energy spectra are close to k−5/3 and temperature variance spectra are noticeably less steep. It is argued that taken together this is good evidence for ‘hard’ turbulence, even if individually each of these properties might have alternative explanations.

scholarly journals Experimental Study of a Boundary Layer on a Heated Flat Plate

2019 ◽  
Vol 213 ◽  
pp. 02002
Author(s):  
Pavel Antoš ◽  
Sergei Kuznetsov
Keyword(s):  
Boundary Layer ◽  
Experimental Study ◽  
Heat Flux ◽  
Flat Plate ◽  
Hot Wire ◽  
Velocity Boundary Layer ◽  
Temperature Boundary Layer ◽  
Temperature Boundary ◽  
Measurement Experiment ◽  
Set Up

Boundary layer on a uniformly heated flat plate was studied experimentally. Both, the velocity boundary layer and the temperature boundary layer, was investigated by means of hot-wire anemometry. A probe with parallel wires was used for velocity-temperature measurement. Experiment was performed in the closed-circuit wind tunnel with several levels of heat flux at the wall. The wall temperature was set up in the interval from 20 ºC to 200 ºC.

scholarly journals Fractional Boundary Layer Flow and Heat Transfer Over a Stretching Sheet With Variable Thickness

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Lin Liu ◽  
Liancun Zheng ◽  
Yanping Chen ◽  
Fawang Liu
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Stretching Sheet ◽  
Magnetic Parameter ◽  
Governing Equations ◽  
Velocity Boundary Layer ◽  
Flow And Heat Transfer ◽  
Temperature Boundary ◽  
Layer Flow ◽  
Fractional Parameter

The paper gives a comprehensive study on the space fractional boundary layer flow and heat transfer over a stretching sheet with variable thickness, and the variable magnetic field is applied. Novel governing equations with left and right Riemann–Liouville fractional derivatives subject to irregular region are formulated. By introducing new variables, the boundary conditions change as the traditional ones. Solutions of the governing equations are obtained numerically where the shifted Grünwald formulae are applied. Good agreement is obtained between the numerical solutions and exact solutions which are constructed by introducing new source items. Dynamic characteristics with the effects of involved parameters on the velocity and temperature distributions are shown and discussed by graphical illustrations. Results show that the velocity boundary layer is thicker for a larger fractional parameter or a smaller magnetic parameter, while the temperature boundary layer is thicker for a larger fractional parameter, a smaller exponent parameter, or a larger magnetic parameter. Moreover, it is thicker at a smaller y and thinner at a larger y for the velocity boundary layer with a larger exponent parameter while for the velocity and temperature boundary layers with a smaller weight coefficient.

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