Shields parameter
The Shields parameter, also called the Shields criterion or Shields number, is a nondimensional number used to calculate the initiation of motion of sediment in a fluid flow. It is a nondimensionalization of a shear stress, and is typically denoted or . It is given by:
where:
- is a dimensional shear stress;
- is the density of the sediment;
- is the density of the fluid;
- is acceleration due to gravity;
- is a characteristic particle diameter of the sediment.
Physical meaning
By multiplying the top and bottom of the Shields parameter by D2, you can see that it is proportional to the ratio of fluid force on the particle to the weight of the particle.
gollark: It's very performant, though.
gollark: It compiled with no warnings so it must be good and very safe and fun.
gollark: In some sense, it works.
gollark: osmarkslibc™ `malloc`:```c#include <stdint.h>#include <stddef.h>static uintptr_t MEMPOS = 1;void* malloc(size_t size) { uintptr_t bees = MEMPOS; MEMPOS += size; return (void*)bees;}void free(void* ptr) { *(char**)ptr = "hello please do not use this address";}```
gollark: I hope you were not malloced using my implementation.
References
- Shields, A.. (1936). Anwendung der Aehnlichkeitsmechanik und der Turbulenzforschung auf die Geschiebebewegung [Application of similarity mechanics and turbulence research on shear flow] (PDF). Mitteilungen der Preußischen Versuchsanstalt für Wasserbau (in German). 26. Berlin: Preußische Versuchsanstalt für Wasserbau. Archived from the original on 2011-07-18.
- Shields, A. (1936). Application of similarity principles and turbulence research to bed-load movement (translated version). Mitteilungen der Preußischen Versuchsanstalt für Wasserbau. 26. Berlin: Preußische Versuchsanstalt für Wasserbau.
External links
- Southard, John. "Chapter 9 – Threshold of movement" (PDF). Lecture notes – Special topics: An introduction to fluid motions, sediment transport, and current-generated sedimentary structures. MIT Open Courseware. Archived from the original (PDF) on 2011-06-29. Retrieved 2011-01-31.
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