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We investigated the influence of oxygen demand (developmental stage) and supply (hypoxia, water flow rate, the chorion and body movements) on the oxygen concentration within the boundary layer next to the chorion of embryos or skin of larvae of rainbow trout (Oncorhynchus mykiss). Oxygen microelectrodes were used to measure dissolved oxygen (DO) within the boundary layer of trout embryos and la...

The receptivity of a Mach 5.92 flat plate boundary layer to periodic two-dimensional wall perturbations is studied by numerical simulations and linear stability theory LST . Free stream flow conditions are the same as the leading edge receptivity experiment of Maslov et al., J. Fluid Mech. 426, 73 2001 . Steady base flow is simulated by solving compressible Navier–Stokes equations with a combin...

The skin friction on a surface is a major concern by engineers. It is widely accepted that turbulent flow has higher friction than laminar flow due to the higher mixing in boundary layer. However, our new high order DNS found that the high friction is generated in a laminar zone in a transitional flow. Whenever the small length scales are generated, the velocity shear becomes very large in the ...

This work aims at understanding the viscous effects of the outer potential flow on Prandtl’s boundary layer. For a body moving with a constant velocity in an otherwise quiescent liquid, the non-zero viscous dissipation of the outer potential flow gives rise to an additional drag, increasing the drag calculated from the boundary layer alone. The drag is considered in three cases here, on a two-d...

For gas flows in microfluidic configurations, the Knudsen layer close to the wall can comprise a substantial part of the entire flowfield and has a major effect on quantities such as the mass flow rate through micro devices. The Knudsen layer itself is characterized by a highly nonlinear relationship between the viscous stress and the strain rate of the gas, so even if the Navier-Stokes equatio...

Occurrence of laminar separation bubbles on solid walls of an elliptic cylinder has been simulated using a recently developed transitional model for boundary layer flows. Computational method is based on the solution of the Reynolds averaged Navier-Stokes (RANS) equations and the eddy-viscosity concept. Transitional model tries to simulate streamwise fluctuations, induced by freestream turbulen...

A problem of great concern in aviation and submarine propulsion is the control of the boundary layer and, in particular, the methods to extend the laminar region as a means to decrease noise and fuel consumption. In this paper we study the flow of air along an airfoil when a layer of ionized gas and a longitudinal electric field are created in the boundary layer region. By deriving scaling solu...

mixed layer is a part of the atmospheric boundary layer in which pollutants are uniformly distributed. it is sensitive to the earth’s surface, controls the flow of heat and momentum between the surface and the free atmosphere, thus playing a key role in atmospheric circulation. most of atmospheric pollution models require the height of the mixed layer as an input to determine the depth of atmos...

Heat and mass convection ............................................................................................................................. 1 Heat convection: what it is ........................................................................................................................ 1 Types of heat convection .......................................................................