Experiments in Fluids

, Volume 8, Issue 3–4, pp 153–160 | Cite as

Distribution of turbulence energy dissipation rates in a Rushton turbine stirred mixer

  • H. Wu
  • G. K. Patterson
  • M. Van Doorn
Originals

Abstract

An approximate method of measuring the turbulence energy dissipation rate (ɛ) in mixers by use of laser-Doppler measurements of the velocity autocorrelation and turbulence energy was successful in yielding remarkably consistent values. The necessary corrections for periodic, non-dissipative velocity fluctuations were made by an autocorrelation method. Two modes of periodic fluctuation were found to be significant. Transformation of the corrected autocorrelations yielded completely normal turbulence energy spectra.

List of symbols

c

fluctuating concentration, C−C

D

impeller diameter

D

molecular diffusivity

f(τ)

autocorrelation function

E1 (n)

one-dimensional energy spectrum function

k

turbulence energy (=q)

Ls

macroscale of segregation

Lx

integral velocity scale

N

impeller rotation rate

NSc

Schmidt number (v/D)

q

turbulence energy (=k)

r

radial distance from impeller shaft

R

impeller radius

T

tank diameter

U, V, W

velocity in x, y, z directions

u, v, w

velocity fluctuations

ur, uθ, uz

fluctuating velocities in radial, tangential, and axial (shaft) directions

Ur, Uθ, Uz

velocities

z

axial distance from impeller disk

Z

tank height

ɛ

turbulence energy dissipation rate

μ

viscosity

τ

time delay

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References

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Copyright information

© Springer-Verlag 1989

Authors and Affiliations

  • H. Wu
    • 1
  • G. K. Patterson
    • 1
  • M. Van Doorn
    • 1
  1. 1.Dept. of Chemical EngineeringUniversity of ArizonaTucsonUSA

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