Search results
Results from the WOW.Com Content Network
The boundary layer thickness, , is the distance normal to the wall to a point where the flow velocity has essentially reached the 'asymptotic' velocity, .Prior to the development of the Moment Method, the lack of an obvious method of defining the boundary layer thickness led much of the flow community in the later half of the 1900s to adopt the location , denoted as and given by
The boundary layer is the bright-green border, most visible on the back of the hand (click for high-res image). In physics and fluid mechanics, a boundary layer is the thin layer of fluid in the immediate vicinity of a bounding surface formed by the fluid flowing along the surface. The fluid's interaction with the wall induces a no-slip ...
A schematic diagram of the Blasius flow profile. The streamwise velocity component () / is shown, as a function of the similarity variable .. Using scaling arguments, Ludwig Prandtl [1] argued that about half of the terms in the Navier-Stokes equations are negligible in boundary layer flows (except in a small region near the leading edge of the plate).
The basis of the Falkner-Skan approach are the Prandtl boundary layer equations. Ludwig Prandtl [2] simplified the equations for fluid flowing along a wall (wedge) by dividing the flow into two areas: one close to the wall dominated by viscosity, and one outside this near-wall boundary layer region where viscosity can be neglected without significant effects on the solution.
The thermal boundary layer thickness is customarily defined as the point in the boundary layer, , where the temperature reaches 99% of the free stream value : such that = 0.99. at a position along the wall. In a real fluid, this quantity can be estimated by measuring the temperature profile at a position along the wall.
The Reynolds and Womersley Numbers are also used to calculate the thicknesses of the boundary layers that can form from the fluid flow’s viscous effects. The Reynolds number is used to calculate the convective inertial boundary layer thickness that can form, and the Womersley number is used to calculate the transient inertial boundary thickness that can form.
Consequently thermal boundary layer is much thicker for liquid metals and much thinner for oils relative to the velocity boundary layer. In heat transfer problems, the Prandtl number controls the relative thickness of the momentum and thermal boundary layers. When Pr is small, it means that the heat diffuses quickly compared to the velocity ...
In fluid dynamics, flow separation or boundary layer separation is the detachment of a boundary layer from a surface into a wake. [1] A boundary layer exists whenever there is relative movement between a fluid and a solid surface with viscous forces present in the layer of fluid close to the surface. The flow can be externally, around a body ...