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In fluid dynamics, the entrance length is the distance a flow travels after entering a pipe before the flow becomes fully developed. [1] Entrance length refers to the length of the entry region, the area following the pipe entrance where effects originating from the interior wall of the pipe propagate into the flow as an expanding boundary layer.
For flow in a pipe of diameter D, experimental observations show that for "fully developed" flow, [n 2] laminar flow occurs when Re D < 2300 and turbulent flow occurs when Re D > 2900. [ 13 ] [ 14 ] At the lower end of this range, a continuous turbulent-flow will form, but only at a very long distance from the inlet of the pipe.
Developmental biology is the study of the process by which animals and plants grow and develop. Developmental biology also encompasses the biology of regeneration , asexual reproduction , metamorphosis , and the growth and differentiation of stem cells in the adult organism.
The flow profiles was first derived by John R. Womersley (1907–1958) in his work with blood flow in arteries. [1] The cardiovascular system of chordate animals is a very good example where pulsatile flow is found, but pulsatile flow is also observed in engines and hydraulic systems, as a result of rotating mechanisms pumping the fluid.
Human embryonic development or human embryogenesis is the development and formation of the human embryo.It is characterised by the processes of cell division and cellular differentiation of the embryo that occurs during the early stages of development.
Top: Idealized cytoplasmic flow in hyphae of Neurospora crassa. Bottom: Actual cytoplasmic flow in hyphae of Neurospora crassa. Microtubules (red) orient themselves perpendicular to flow as they exit the septal hole, deaccelerating the flow faster than the idealized case preventing the formation of eddies on the downstream side of the septum.
Biological processes are those processes that are necessary for an organism to live and that shape its capacities for interacting with its environment. Biological processes are made of many chemical reactions or other events that are involved in the persistence and transformation of life forms.
A functional explanation for the enigmatic turning of the heart and bowels is lacking, but one theory does give an explanation for the evolution and development of this phenomenon. According to this axial twist theory , this is due to a twist in the body of all vertebrates that occurs in the early embryo.