Entrance Length
Entrance Length - Related Videos
07:19
A 3D Printed Pollen Trap for Bumble Bee (Bombus) Hive Entrances
0 Views •
Cited by 7 •
2020
We present a non-lethal and automated mechanism to collect pollen from bumble bee (Bombus) workers returning to a hive. Instructions for producing, preparing, installing and using the devices are included. By using 3D-printed objects, modification to the design was timely, efficient and allowed for quick turnaround for testing.
08:24
Injections of Lipopolysaccharide into Mice to Mimic Entrance of Microbial-derived Products After Intestinal Barrier Breach
0 Views •
Cited by 48 •
2018
Here a protocol to mimic the entrance of bacterial-derived compounds after intestinal barrier breach is presented. A low sublethal dose of lipopolysaccharide was injected systemically into mice, which were monitored for 24 h post-injection. The expression of pro-inflammatory cytokines was determined at several time points in spleen, liver, and colon.
13:31
High Speed Sub-GHz Spectrometer for Brillouin Scattering Analysis
0 Views •
Cited by 42 •
2015
Here we present a protocol to build a rapid Brillouin spectrometer. Cascading virtually imaged phase array (VIPA) etalons achieve a measurement speed more than 1,000 times faster than traditional scanning Fabry-Perot spectrometers. This improvement provides the means for Brillouin analysis of tissue and biomaterials at low power levels in vivo.
06:03
A Push-pull Protocol to Reduce Colonization of Bird Nest Boxes by Honey Bees
0 Views •
Cited by 1 •
2016
Preventing colonization of bird nest boxes by invasive Africanized honey bees is important for conservation efforts of nest-site limited birds. We provide an integrated pest management approach to "push" bees away from nest boxes with a repellant insecticide, permethrin, and "pull" them toward pheromone baited swarm traps.
14:19
A Basic Positron Emission Tomography System Constructed to Locate a Radioactive Source in a Bi-dimensional Space
0 Views •
2016
We present a simple but well-constructed Positron Emission Tomography (PET) system and elucidate its basic working principles. The goal of this protocol is to guide the user in constructing and testing a simple PET system.
FAQs
Wall friction first affects fluid layers adjacent to the solid boundary, producing boundary layers that grow inward from the walls. As these layers occupy more of the cross section, they progressively alter the velocity distribution and wall shear. The flow therefore remains spatially changing near the inlet until the relevant velocity conditions stabilize.
The estimate depends on flow regime, channel or duct geometry, fluid properties, and boundary conditions. These variables determine how the inlet disturbance develops and how quickly the velocity or temperature field settles. Considering them together helps engineers avoid treating every pipe, channel, or duct as though it had the same developing-flow region.
Velocity and temperature profiles describe different aspects of internal flow development. A velocity field may reach a stable distribution while thermal conditions continue changing, or the reverse, depending on the relevant boundary conditions and fluid properties. Engineers should therefore identify whether the design concerns momentum, temperature, wall shear, or heat transfer before selecting an entrance-length criterion.
Developing flow retains changes in its velocity distribution, wall shear, or temperature conditions as the fluid moves downstream. Fully developed flow represents the point at which the selected profile or condition has stabilized. This distinction matters because calculations based on stabilized behavior may not accurately describe regions close to an inlet.
Engineers first identify the inlet conditions and the relevant flow quantity, such as velocity or temperature. They then estimate the distance required for that quantity to stabilize using the system's flow regime, geometry, fluid properties, and boundary conditions. This distance separates the developing region from the portion suitable for fully developed-flow analysis.
The developing region contains evolving wall shear and velocity distributions, so it should be distinguished from a region where those conditions have stabilized. Accounting for entrance length improves pressure-drop predictions by matching the analysis to the actual state of the flow. This is especially relevant when evaluating internal-flow components near an inlet.
A component placed within the developing region encounters flow conditions that are still changing with downstream distance. Locating or evaluating components with the entrance length in mind helps engineers determine whether the surrounding velocity, wall-shear, or temperature conditions are stabilized. That distinction supports more appropriate design and performance assessments in fluid systems.
The concept applies broadly to internal flow through pipes, channels, and ducts. It supports decisions about pressure-drop analysis, heat-transfer prediction, and the placement of components relative to an inlet. In each case, recognizing the developing region prevents engineers from applying fully developed assumptions before the relevant flow or thermal conditions have stabilized.