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The Prandtl number (Pr) or Prandtl group is a dimensionless number, named after the German physicist Ludwig Prandtl, defined as the ratio of momentum diffusivity to thermal diffusivity. [1] The Prandtl number is given as:
c p is the specific heat capacity at constant pressure. In the field of fluid mechanics, many sources define the Lewis number to be the inverse of the above definition. [3] [4] The Lewis number can also be expressed in terms of the Prandtl number (Pr) and the Schmidt number (Sc): [5] =
A gyration point can be replaced by a screw axis denoted by a number, n, ... mm2 Pmm2: P m m 2: 13s (::): ... P 4 2 /n 2 1 /c 2/m
Converted to SI units, 1 darcy is equivalent to 9.869 233 × 10 −13 m 2 or 0.9869233 μm 2. [4] This conversion is usually approximated as 1 μm 2 . This is the reciprocal of 1.013250—the conversion factor from atmospheres to bars .
The transistor count is the number of transistors in an electronic device (typically on a single substrate or silicon die).It is the most common measure of integrated circuit complexity (although the majority of transistors in modern microprocessors are contained in cache memories, which consist mostly of the same memory cell circuits replicated many times).
= 0.514 77 3 m/s mach number: M: Ratio of the speed to the speed of sound [note 1] in the medium (unitless). ≈ 340 m/s in air at sea level ≈ 295 m/s in air at jet altitudes metre per second (SI unit) m/s ≡ 1 m/s = 1 m/s mile per hour: mph ≡ 1 mi/h = 0.447 04 m/s: mile per minute: mpm ≡ 1 mi/min = 26.8224 m/s: mile per second: mps ≡ ...
The Stanton number (St), is a dimensionless number that measures the ratio of heat transferred into a fluid to the thermal capacity of fluid. The Stanton number is named after Thomas Stanton (engineer) (1865–1931). [1] [2]: 476 It is used to characterize heat transfer in forced convection flows.
D is the diffusion coefficient (in m 2 /s), D 0 is the maximal diffusion coefficient (at infinite temperature; in m 2 /s), E A is the activation energy for diffusion (in J/mol), T is the absolute temperature (in K), R ≈ 8.31446 J/(mol⋅K) is the universal gas constant.