A Thin-Film Probe for the Measurement of a Three-Dimensional Velocity Vector

1978 ◽  
Vol 20 (6) ◽  
pp. 327-333
Author(s):  
J. K. Aggarwal ◽  
B. J. Bellhouse
Keyword(s):  
Thin Film ◽  
Boundary Layer ◽  
Data Acquisition ◽  
Water Flow ◽  
Velocity Vector ◽  
Three Dimensional ◽  
Boundary Layer Theory ◽  
Water Tank ◽  
Hot Film ◽  
Steady Velocity

A new hot-film probe intended for the measurement of velocity, in magnitude and direction, in three-dimensional water flow is described. Using boundary layer theory, the response of the probe to steady velocity is derived and is found to agree closely with calibrations. The probe has proved to be robust and durable; it produced reliable and repeatable calibrations when towed in a water tank. The method of data acquisition and the technique used for computing the velocity vector are reported.

scholarly journals Three-Dimensional Casson Nanofluid Thin Film Flow over an Inclined Rotating Disk with the Impact of Heat Generation/Consumption and Thermal Radiation

Coatings ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 248 ◽  
Author(s):  
Anwar Saeed ◽  
Zahir Shah ◽  
Saeed Islam ◽  
Muhammad Jawad ◽  
Asad Ullah ◽  
...  
Keyword(s):  
Thin Film ◽  
Boundary Layer ◽  
Differential Equations ◽  
Thermal Boundary Layer ◽  
Energy Transport ◽  
Film Flow ◽  
Three Dimensional ◽  
Concentration Profiles ◽  
Thin Film Flow ◽  
The Impact

In this research, the three-dimensional nanofluid thin-film flow of Casson fluid over an inclined steady rotating plane is examined. A thermal radiated nanofluid thin film flow is considered with suction/injection effects. With the help of similarity variables, the partial differential equations (PDEs) are converted into a system of ordinary differential equations (ODEs). The obtained ODEs are solved by the homotopy analysis method (HAM) with the association of MATHEMATICA software. The boundary-layer over an inclined steady rotating plane is plotted and explored in detail for the velocity, temperature, and concentration profiles. Also, the surface rate of heat transfer and shear stress are described in detail. The impact of numerous embedded parameters, such as the Schmidt number, Brownian motion parameter, thermophoretic parameter, and Casson parameter (Sc, Nb, Nt, γ), etc., were examined on the velocity, temperature, and concentration profiles, respectively. The essential terms of the Nusselt number and Sherwood number were also examined numerically and physically for the temperature and concentration profiles. It was observed that the radiation source improves the energy transport to enhance the flow motion. The smaller values of the Prandtl number, Pr, augmented the thermal boundary-layer and decreased the flow field. The increasing values of the rotation parameter decreased the thermal boundary layer thickness. These outputs are examined physically and numerically and are also discussed.

scholarly journals Experimental observation of frequency lock-in of roughness-induced instabilities in a laminar boundary layer

2019 ◽  
Vol 870 ◽  
pp. 680-697
Author(s):  
Dominik K. Puckert ◽  
Ulrich Rist
Keyword(s):  
Boundary Layer ◽  
Aspect Ratio ◽  
Laminar Boundary Layer ◽  
Roughness Element ◽  
Water Channel ◽  
Three Dimensional ◽  
Boundary Layer Theory ◽  
Linear Stability Theory ◽  
Mode Decomposition ◽  
Lock In

The interaction of disturbance modes behind an isolated cylindrical roughness element in a laminar boundary layer is investigated by means of hot-film anemometry and particle image velocimetry in a low-turbulence laminar water channel. Both sinuous and varicose disturbance modes are found in the wake of a roughness with unit aspect ratio (diameter/height $=$ 1). Interestingly, the frequency of the varicose mode synchronizes with the first harmonic of the sinuous mode when the critical Reynolds number from three-dimensional global linear stability theory is exceeded. The coupled motion of sinuous and varicose modes is explained by frequency lock-in. This mechanism is of great importance in many aspects of nature, but has not yet received sufficient attention in the field of boundary-layer theory. A Fourier mode decomposition provides detailed analyses of sinuous and varicose modes. The observation is confirmed by a second experiment with the same aspect ratio at a different position in the laminar boundary layer. When the aspect ratio is increased, the flow is fully governed by the varicose mode. Thus, no frequency lock-in can be observed in this case. The significance of this work is to explain how sinuous and varicose modes can co-exist behind a roughness and to propose a mechanism which is well established in physics but not encountered often in boundary-layer theory.

scholarly journals The global characteristics of the three-dimensional thermal convection inside a spherical shell

1997 ◽  
Vol 4 (1) ◽  
pp. 19-27 ◽  
Author(s):  
J. Arkani-Hamed
Keyword(s):  
Boundary Layer ◽  
Nusselt Number ◽  
Rayleigh Number ◽  
Spherical Shell ◽  
Critical Rayleigh Number ◽  
Three Dimensional ◽  
Horizontal Layer ◽  
Boundary Layer Theory ◽  
Physical Parameters ◽  
Rayleigh Numbers

Abstract. The Rayleigh number-Nusselt number, and the Rayleigh number-thermal boundary layer thickness relationships are determined for the three-dimensional convection in a spherical shell of constant physical parameters. Several models are considered with Rayleigh numbers ranging from 1.1 x 102 to 2.1 x 105 times the critical Rayleigh number. At lower Rayleigh numbers the Nusselt number of the three-dimensional convection is greater than that predicted from the boundary layer theory of a horizontal layer but agrees well with the results of an axisymmetric convection in a spherical shell. At high Rayleigh numbers of about 105 times the critical value, which are the characteristics of the mantle convection in terrestrial planets, the Nusselt number of the three-dimensional convection is in good agreement with that of the boundary layer theory. At even higher Rayleigh numbers, the Nusselt number of the three-dimensional convection becomes less than those obtained from the boundary layer theory. The thicknesses of the thermal boundary layers of the spherical shell are not identical, unlike those of the horizontal layer. The inner thermal boundary is thinner than the outer one, by about 30- 40%. Also, the temperature drop across the inner boundary layer is greater than that across the outer boundary layer.

scholarly journals Three-dimensional magnetohydrodynamic nanofluid thin-film flow with heat and mass transfer over an inclined porous rotating disk

2019 ◽  
Vol 11 (8) ◽  
pp. 168781401986975 ◽  
Author(s):  
Muhammad Jawad ◽  
Zahir Shah ◽  
Aurangzeb Khan ◽  
Saeed Islam ◽  
Hakeem Ullah
Keyword(s):  
Thin Film ◽  
Boundary Layer ◽  
Differential Equations ◽  
Three Dimensional ◽  
Rotating Disk ◽  
Liquid System ◽  
Thin Film Flow ◽  
Homotopy Analysis ◽  
Injection Effect ◽  
Film Flows

In the present study, the three-dimensional Darcy–Forchheimer magnetohydrodynamic thin-film nanofluid containing flow over an inclined steady rotating plane is observed. Nanofluid thin-film flows are taken thermally radiated and suction/injection effect is also considered. By similarity variables, the partial differential equations are transformed into a set of first-ordinary differential equations (ODES). By Homotopy Analysis Method, the required ODES is solved. The boundary layer over an inclined steady rotating plane is plotted and observed in detail for the velocity, [Formula: see text], and [Formula: see text] profiles. The influence of various embedded parameters such as variable thickness, [Formula: see text]Pr, and thermophoretic parameter on velocity, [Formula: see text], and [Formula: see text] profile. The influence of many parameters is explained by graphs for the velocity, [Formula: see text], and [Formula: see text]. The crucial terms of Nusselt number and Sherwood number have also been observed numerically and physically for [Formula: see text] and [Formula: see text]. Radiation phenomena is the cause of energy to the liquid system. For more rotation parameters, the thermal boundary-layer thickness is reduced.

Behaviour and transport of oil under smooth ice

1987 ◽  
Vol 14 (4) ◽  
pp. 510-518 ◽  
Author(s):  
James Puskas ◽  
Edward McBean ◽  
Nicholas Kouwen
Keyword(s):  
Boundary Layer ◽  
Water Flow ◽  
Friction Force ◽  
Oil Spills ◽  
Water Film ◽  
Boundary Layer Theory ◽  
Physical Models ◽  
Velocity Variation ◽  
Water Current ◽  
Ice Friction

Mathematical and physical models are used in studying transport of oil slicks beneath ice in the presence of an ambient water current. The mathematical expressions for the relevant forces are developed by utililizing basic boundary layer theory and considering the physical properties of the oils and are verified from the laboratory experiments. Three different crude oils are utilized beneath freshwater ice under various flow conditions in the experiments.The transport of oil slicks oriented longitudinally to the direction of the water flow are modelled by the summation of the shear force at the oil – water interface and the oil – ice friction force. Oil slicks oriented transverse to the direction of the water flow are subjected to an additional form-drag force acting as the primary driving force.For oils with low viscosities, the oil – ice friction force can be approximated by assuming "no-slip" at the oil – ice interface. Oils with high viscosities move almost as a solid mass, with the majority of the velocity variation taking place in a thin water film separating the oil and the ice. Key words: boundary layer theory, environmental engineering, ice, mathematical models, oil spills, physical models.

Aerodynamic Performance of Large Centrifugal Compressors

1982 ◽  
Vol 104 (4) ◽  
pp. 796-804 ◽  
Author(s):  
Fumikata Kano ◽  
Noriyuki Tazawa ◽  
Yoshiteru Fukao
Keyword(s):  
Boundary Layer ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Design Procedure ◽  
Suction Side ◽  
Aerodynamic Performance ◽  
Boundary Layer Theory ◽  
Air Separation ◽  
Three Dimensional Flow ◽  
Dimensional Measurements

The aerodynamic performance of impellers and diffusers of the large centrifugal compressor were studied. A performance design procedure based on the quasi-three-dimensional flow analysis which is combined with the boundary layer theory was developed. The conditions of the boundary layer at the impeller exit and at the diffuser vane throat were calculated, and the three-dimensional measurements were carried out. This result shows that the low momentum flow is accumulated at the corner of the shroud and the blade suction side of the impeller. These results were applied to the development of a large four-stage isothermal compressor which handles the air for an air separation apparatus. This was tested in the field and showed an isothermal efficiency of 76 percent.

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