Parametric method in the boundary-layer theory of ionized gas whose electroconductivity is a function of the longitudinal velocity gradient

2001 ◽  
Vol 147 (1-4) ◽  
pp. 35-44
Author(s):  
B. Obrović
Keyword(s):  
Boundary Layer ◽  
Velocity Gradient ◽  
Longitudinal Velocity ◽  
Parametric Method ◽  
Boundary Layer Theory ◽  
Ionized Gas

scholarly journals Investigation of the ionized gas flow adjacent to porous wall in the case when electroconductivity is a function of the longitudinal velocity gradient

2010 ◽  
Vol 14 (1) ◽  
pp. 89-102
Author(s):  
Slobodan Savic ◽  
Branko Obrovic ◽  
Dusan Gordic ◽  
Sasa Jovanovic
Keyword(s):  
Boundary Layer ◽  
Electric Fields ◽  
Velocity Gradient ◽  
Gas Flow ◽  
Numerical Solutions ◽  
Longitudinal Velocity ◽  
Porous Wall ◽  
The Body ◽  
Ionized Gas ◽  
Boundary Layer Equations

This paper studies the laminar boundary layer on a body of an arbitrary shape when the ionized gas flow is planar and steady and the wall of the body within the fluid porous. The outer magnetic field is perpendicular to the fluid flow. The inner magnetic and outer electric fields are neglected. The ionized gas electroconductivity is assumed to be a function of the longitudinal velocity gradient. Using transformations, the governing boundary layer equations are brought to a general mathematical model. Based on the obtained numerical solutions in the tabular forms, the behavior of important non-dimensional quantities and characteristics of the boundary layer is graphically presented. General conclusions about the influence of certain parameters on distribution of the physical quantities in the boundary layer are drawn.

A laboratory study of fluid flow and microhabitat selection by larvae of Simulium vittatum (Diptera: Simuliidae)

1992 ◽  
Vol 70 (3) ◽  
pp. 582-596 ◽  
Author(s):  
Jean O. Lacoursière
Keyword(s):  
Boundary Layer ◽  
Velocity Gradient ◽  
Longitudinal Velocity ◽  
Boundary Layer Separation ◽  
The Body ◽  
Surface Shear Stress ◽  
Microhabitat Selection ◽  
Surface Shear ◽  
Stagnation Line ◽  
Simulium Vittatum

Microhabitat selection by Simulium vittatum Zetterstedt larvae in a flume was studied at different mainstream velocities on two substrates: a thin flat plate parallel to the flow and a cylinder in cross flow. The results do not support the generally accepted assumptions that simuliid larvae keep within the boundary layer to avoid the direct influence of mainstream current and that they select the fastest velocity available when offered a longitudinal velocity gradient within their tolerance range. Instead, larvae gathered along the zone of boundary layer separation and remained along the stagnation line at the leading point of the cylinder when artificially positioned there. Further, under most conditions, larvae avoided zones of maximum surface shear stress. Larval reaction to hydraulic changes was immediate. It is hypothesized that S. vittatum larvae first scan the velocity profile at the substrate, initially moving toward increasing flow velocity (or water acceleration). They then cue on a steep velocity gradient along the body as part of the processes involved in choosing a location for suspension feeding. Such conditions would maximize particle flux through the labral fans and minimize drag forces on the bulbous posterior abdomen. This study provides the first direct evidence for microhydraulic factors as causative agents in the formation of simuliid larval assemblages.

scholarly journals The influence of variation of electroconductivity on ionized gas flow in the boundary layer along a porous wall

2006 ◽  
Vol 33 (2) ◽  
pp. 149-179 ◽  
Author(s):  
Slobodan Savic ◽  
Branko Obrovic
Keyword(s):  
Boundary Layer ◽  
Gas Flow ◽  
Longitudinal Velocity ◽  
Porous Wall ◽  
Outer Edge ◽  
Ionized Gas ◽  
Boundary Layer Equations ◽  
Characteristic Boundary ◽  
Longitudinal Variable ◽  
Similarity Method

This paper investigates ionized gas flow in the boundary layer when its electroconductivity is varied. The flow is planar and the contour is porous. At first, it is assumed that the ionized gas electroconductivity ? depends only on the longitudinal variable. Then we adopt that it is a function of the ratio of the longitudinal velocity and the velocity at the outer edge of the boundary layer. For both electroconductivity variation laws, by application of the general similarity method, the governing boundary layer equations are brought to a generalized form and numerically solved in a four-parametric three times localized approximation. Based on many tabular solutions, we have shown diagrams of the most important nondimensional values and characteristic boundary layer functions for both of the assumed laws. Finally, some conclusions about influence of certain physical values on ionized gas flow in the boundary layer have been drawn. .

INVERSE PROBLEMS OF BOUNDARY LAYER THEORY

2018 ◽  
Vol 49 (8) ◽  
pp. 793-807
Author(s):  
Vladimir Efimovich Kovalev
Keyword(s):  
Boundary Layer ◽  
Inverse Problems ◽  
Boundary Layer Theory

scholarly journals Impact of Binary Chemical Reaction and Activation Energy on Heat and Mass Transfer of Marangoni Driven Boundary Layer Flow of a Non-Newtonian Nanofluid

Processes ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 702
Author(s):  
Ramanahalli Jayadevamurthy Punith Gowda ◽  
Rangaswamy Naveen Kumar ◽  
Anigere Marikempaiah Jyothi ◽  
Ballajja Chandrappa Prasannakumara ◽  
Ioannis E. Sarris
Keyword(s):  
Heat Transfer ◽  
Activation Energy ◽  
Boundary Layer ◽  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Velocity Gradient ◽  
Boundary Layer Flow ◽  
Biological Fluids ◽  
Porosity Parameter ◽  
Layer Flow

The flow and heat transfer of non-Newtonian nanofluids has an extensive range of applications in oceanography, the cooling of metallic plates, melt-spinning, the movement of biological fluids, heat exchangers technology, coating and suspensions. In view of these applications, we studied the steady Marangoni driven boundary layer flow, heat and mass transfer characteristics of a nanofluid. A non-Newtonian second-grade liquid model is used to deliberate the effect of activation energy on the chemically reactive non-Newtonian nanofluid. By applying suitable similarity transformations, the system of governing equations is transformed into a set of ordinary differential equations. These reduced equations are tackled numerically using the Runge–Kutta–Fehlberg fourth-fifth order (RKF-45) method. The velocity, concentration, thermal fields and rate of heat transfer are explored for the embedded non-dimensional parameters graphically. Our results revealed that the escalating values of the Marangoni number improve the velocity gradient and reduce the heat transfer. As the values of the porosity parameter increase, the velocity gradient is reduced and the heat transfer is improved. Finally, the Nusselt number is found to decline as the porosity parameter increases.

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